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German early warning Ground Radar

"SECRET A. D. I. (K) Report No. 390/1945

German early warning Ground Radar.
1. This report is the tenth of the series dealing with radio
and radar equipment in the Luftwaffe. As in the case of the
previous nine reports (A.D.I.(K) 343, 357, 362, 365, 369, 370
and 330/1945), it is based on interrogation of General
Nachrichtenführer MARTINI, Director General of Signals, and
some members of his staff, and has been supported by a number
of relevant documents of recent date which were in the
possession of the General's Chief of Staff.

Early History.
2. As recounted in A.D.I.(K) 343/1945 and again mentioned in
A.D.I.(K) 365/1945, the Freya, which became the first standard
early-warning radar set for the G.A.F., was developed by the
firm of Gema, Berlin, with the encouragement of the Navy. The
first Freyas were in operation as naval coast watchers in 1938
at a time when the G.A.F. was only thinking of radar in terms
of searchlights and Flak.
3. The Technisches Amt wished to push 50 cm. wavelength
like that of Würzburg, but the Navy backed the longer
wavelength of Freya, and General MARTINI, who immediately
appreciated the advantage of a wide-angle apparatus of Freya
type to early warning, asked that a number of Freyas should be
allocated to the G.A.F.
4. In early 1939 one of the present P/W, Oberst Ing. HENTZ
was selected from among the Köthen staff to take charge of the
first experimental Freya used by the G.A.F. in that year.
It was thought at first that the Freya would only give
indications over the sea, but during the march on Prague in
the first part of 1939 an experimental Freya was set up in the
Riesen Gebirge in order to watch Czech aircraft which might
react to the German advance. This experiment was not a
success, as the signals operators had not been expecting to
find their tube cluttered up with permanent echoes.
5. At the outbreak of war the G.A.F. possessed eight Freya
stations distributed round the East and North Frisian islands
guarding the Heligoland Bight and the approaches to the North
Sea ports. These Freyas proved their value during the early
Bomber Command raids on Cuxhaven and Wilhelmshaven etc., when
some outstanding successes were registered by German fighters,
which were vectored on to the bomber formation as a result of
the early-warning obtained by the Freyas. It was this success
which convinced the G.A.F. of the practicability of radar as
an early-warning device.

Early Developments.
6. The range of the early Freya was of the order of 80 km and
their accuracy of the order of a few degrees. No height
finding facilities were available. The height finding problem
at close range was solved by directing a Würzburg on to the
target when it came within the range of the latter, which in
these days was about 30 km. This system of height measurement
continued to be the only practical one for a long period,
although the field operators had put in requirements for
height finding Freya apparatus as early as 1940.
7. Experiments by the G.A.F. produced the Wassermann, but
the German Navy experimented with the object of introducing
height finding facilities in the Freyas, and the N.V.K. at
Pelzerhaken produced the "Chinese" and "Tiefland". The former
gave maximum location by means of a compensator in an serial
system inclined at 45° and was used for angles greater than
15°, whilst the latter was intended for angles less than 15°.
The combination of the two mounted on the Freya was known as
the “Malaya”.
8. Measurement of height with the Tiefland was possible
between 2° and about 15° over level terrain; measurement of
angles of less than 5° was, however, very inaccurate and range
was actually less than that of the Würzburg-Riese. Over uneven
terrain, measurement of the vertical angle was impossible.
9. The Tiefland had the disadvantage of being complicated in
operation - a large field of reflector nets was also necessary
- in addition to which it gave no better performance than the
Würzburg-Riese. Its use would only have been justified had it
been a device which could be moved easily and quickly and had
there not been restrictions on the selection of suitable sites
for its mounting.
10. Freya Fahrstuhl was designed by Köthen as early as 1943
but was never put into large-scale production, and was not
satisfactory. This apparatus depended on the difference of
phase observed between direct ray and ground reflection to
give height.
11. Finally, in 1944 methods or swinging the beam
electrically were used in the Wassermann for height
measurement, but the Würzburg remained the basic means of
measuring the elevation up to the end of the war. The D/F
accuracy of the Freya was greatly improved when the split beam
or A.N. technique was introduced in 1942, end this made Freya
valuable for fighter control on the Egon system.
12. The range of Freya, naturally dependent on height of an
objective, was about 150 km. but this was not considered
sufficient for the early-warning service and efforts were made
in 1942 to produce early-warning apparatus with greater range.
The first of these was the Wassermann which improved the
early-warning range to about 200-250 km, while the Mammut,
used by the Navy for coast watcher purposes, was also used by
the G.A.F. and gave ranges up to about 300 km. Finally
Elefant, which gave ranges up to 350 km., was built and came
into operation in about 1944.
13. By the middle of 1943 an elaborate early-warning service
covering the whole of Germany and composed of sites with both
Freyas, Würzburgs and Giant Würzburgs had been built up, and a
number of Wassermann chimneys were in operation along the
coast of Europe.
14. The great improvement in D/F accuracy resulting from the
split beam technique was utilised by KAMMHUBER to develop his
box system of night fighting, and in fact at this time it was
strictly forbidden for a night fighter to fly any form of
night defence other than the close control of the KAMMHUBER
box system.
15. Other methods of fighter control namely the Egon and
Bonito, were under development, and of these the former also
used the Freya wavelength for range and D/F.
Effect of first use of Window.
16. When Window was first used in July 1943 the whole of the
early-warning system as well as the night fighter control
system broke down completely.
17. The first German reaction to the use of Window was to
attempt to filter it out or obtain some method of
distinguishing between blips due to window and those due to
the aircraft itself. Virtually no work had been done on this
problem before July 1943 because GOERING had been so
frightened by the prospect of Window being used by the enemy
that the theoretical possibilities had been hushed up and
scientists has not being allowed to work on the problem (cf.
A.D.I.(K) 334/1945).
13. Nevertheless, when Window was first used by the Allies, it
was only a matter of some ten days before the first solution
to the Window problem for the Würzburg was forthcoming in the
shape of the Würzlaus, which relied on the Doppler effect.
High priority was given to the problem and even money prizes
were offered for solutions.
19. Three main types of equipment were evolved as a result of
the various solutions proposed; one was Taunus, which gave
greater blip resolution, another was the propeller modulation
type such as Nürnberg and the third was based on the Doppler
effect, the latter being termed Laus A—J devices. Of these the
Freyalaus for Freya and Wasserfloh for the Wassermann were not
used operationally till 1944.

Effect of Further Countermeasures.
20. As Allied countermeasures became more intense and
electronic jamming was also used, the signals staff decided
that it should be the genera1 policy to provide all types of
radar with the facility for a change of frequency. The first
efforts to do this were brought about by mechanical trombone
tuning of the aerials so that two or three neighbouring
wavelengths could be used. This was termed the WISMAR
21. Sometime in 1943 Dr. SCHULTER of the firm Siemens
developed the Breitband (wide band) aerial which enabled a
much greater frequency spread to be used. This principle was
termed Voll Wismar and with increasing experience was to be
applied to all types of ground radar. At the same time Freya
and Würzburg were allotted different "Inseln" or frequency
bands in the hope that some of these bands would not be jammed
locally. This policy was carried to great lengths, but Allied
countermeasures still remained extremely effective.
22. Either owing to the weakness of German centimetre
technique, or to a lack of appreciation of the value of
centimetre wavelengths, the main trend in avoiding British
countermeasures was towards longer wavelengths, and special
Köthen Freyas using wavelengths of 5 and 8 metres were
prepared. When jamming on the more normal wavelengths
became severe these reserve sets were operated for a minimum
period often only a few seconds, in order not to compromise
the wavelength, and an effort was made to obtain a clear
picture of the air situation with their aid.
23. Eventually wavelengths up to 13 metres came into use for
early-warning with giant sets such as Elefant.
British Transmissions as an Aid to Early Warning.
24. Despite all these precautions, and despite the fact that
P/W claimed that many of these wavelengths were not
effectively jammed, it frequently happened that the earlywarning
service was unable to obtain a clear picture of the
situation and recourse had to be made to indirect means. The
monitoring service was of particular value in this respect,
and they successfully maintained their point of view that it
was not worthwhile jamming the fighter R/T because D/F’ing of
this provided excellent early warning.
25. The fact that British night bomber crews were in the
habit of using Monica and H2S from the very beginning of their
flights was also of great assistance in supplementing the
early-warning picture. In the same way Allied I.F.F. was of
great value, and special Freyas known as Freya Flamme which
covered the I.F.F. frequency band were erected on some
important early-warning sites.
26. Finally, an ingenious system which was invented by Oberst
Postrat SCHOLZ called Klein Heidelberg utilised the reflection
of the transmissions from British C.H. stations and was
regarded as virtually unjammable.
Development of Panoramic Presentation.
27. As early as 1940 a requirement was put up for a panoramic
presentation for early-warning radar, but no great progress
seems to have been made until the discovery that H2S was using
a P.P.I. successfully. Difficulties were encountered with the
early types such as Propeller developed by Lorenz and it was
not until early 1944 that the Jagdschloss sets came into
existence. These were originally used entirely for early
warning and not with the idea that night-fighter aircraft
could be controlled with their aid. It was not until 1945,
when the value of Jagdschloss was fully appreciated and it was
numerous enough to cover 1st class radar sites throughout
Germany that some efforts were made in its employment for
control of night fighters.
28. With the intended introduction of Neuling I.F.F., which
could distinguish not only between friend and foe but between
individual crews as described in A.D.I.(K) 365/1945, fighter
control from panoramic presentation was to be greatly

Day Fighter Control.
29. The necessity for day-fighter control from ground radar
stations was early appreciated by the Signals staff, and the
Battle of Britain proved to them how successfully it could be
used by air force inferior in numbers. Spasmodic attempts were
made to introduce it into the G.A.F. but the German fighter
tradition was too strong, and the pilots would not accept
ground control.
30. It was not until 1943 that close ground control on the
Egon system using the FuGe 25A in the aircraft was introduced.
Control of Night Fighters.
31. With KAMMHUBER’s box system two Würzburg sets were used -
one to follow the target and one to follow the fighter, the
positions of each being projected on to the map by means of
the so-called Seeburg Tisch. So long as there was no jamming
of ground radar, this method was successful and could place a
fighter within 200-400 metres of the target. Later the
Würzburg Riese was used and the majority of these sets were
allocated for this purpose.
32. A suggestion had been made that the Würzburg 50 cm.
transmission should be used simultaneously for giving the
fighter his vectors and a system named Sprechstange was
experimented with. It was rapidly found that, if the operator
failed to hold the fighter in the beam, the pilot received no
instructions from the ground, and so vital instructions might
not be heard. For this reason it was soon abandoned as not

I.F.F. Problems.
33. The FuGe 25A was originally designed by the firm of Gema
for use with the first Freyas operating on 2.4 metres. As
recounted in A.D.I.(K). 365/1945 it became the standard German
airborne I.F.F. set in 1942 and was used with the Kuh
transmitter and Gemse receiver on all ground radar
installations, whatever the wavelength, with the exception of
the Würzburg series. A full description of the problems of
ground radar has been given in the above-mentioned report.
Plotting of High Flying Aircraft.
34. In 1944 it was found that the very high level Mosquito
bomber attacks on the Reich sometimes crossed the coast
unplotted, and at best were only detected intermittently after
passing the coastal screen of Wassermanns which could swing
their beams upward electrically. The reason for this was that
the main lobs of Freya only went up to about 8,000 metres.
There were two subsidiary lobes, the higher of which reached
to 12,000 metres, but the latter only gave limited coverage at
this height over an estimated range of 70 km.
35. The Würzburg beam was too narrow and did not give general
coverage, while Freya Fahrstuhl, which could also be utilised
for aircraft flying at great height, had hardly been
introduced into operations. For this reason considerable use
was made of the Würzburg Riese-G which was a Giant Würzburg
with a very narrow 50 cm. beam, with additional Freya aerials
on 2 metres, set in the paraboloid, giving a wide beam
coverage as well. As the circle paraboloid could be tilted
upwards, excellent high coverage was obtained and high fliers
were plotted with its aid.

Plotting of Low-Flying Aircraft.
36. The Germans were fully aware of lack of low cover, which
enabled aircraft flying low over the sea to cross the coast
unnoticed. A number of experiments were conducted to overcome
this disadvantage by placing special aerial arrays at
considerable height above the ground as for instance in the
case of the Würzmann using the Würzburg frequency and the
Tiefentwiel using the Hohentwiel A.S.V. frequency.
37. Some experiments were also conducted with wavelengths of
about 20 metres with the idea, it was believed, of making use
of the curved path which those waves followed. The experiments
were never completed, as this band was interfered with by
communications signals transmitted on the same wavelength.
38. Experiments had also been made at Köthen with Taunus
equipment coupled to the Freya to obtain extremely high
resolution. A Fieseler Storch aircraft was used, flying at 150
metres over flat country, and under these conditions the
aircraft could just be seen at ranges of 4 or 5 km. through
the ground returns due to woods and houses. It was concluded,
however, that this range was so small that no advantage was to
be gained.

39. Freya was manufactured by the firm of Gema, Berlin,
which, at the outbreak of war, was only a small establishment
largely financed by the Navy. Members of the Technisches Amt,
as well as of MARTINI’s staff, criticised the firm, severely,
saying that they lacked experience of manufacturing and were
unwilling to make themselves adaptable. They described the
Freya Stand for instance as a “cast iron monstrosity”, which
they felt could easily have been made very much lighter in
weight and manufactured more simply.
40. Despite this complaint against Gema, it was a principle
that all ground radar apparatus should be of fairly simple
construction so that it could be made mobile. A few days after
the invasion of Norway the Germans were experiencing
considerable trouble from bomber raids in the Stavanger area
and an urgent request was sent out from there for a Freya to
be supplied. This job was given to one of the present P/W, and
within three days of receiving it a Freya LZ Stand had been
dismantled and packed into three Ju.52's and transported to
Stavanger. Eight days after the reception of the order the
Freya was operating.
41. At the beginning of the war the G.A.F. possessed eight
Freyas. At the end of the war over 1,200 had been manufactured
and a document dated 1st January 1945 states that 671 were in
operation at that time.
42. Owing to the incidence of all forms of Allied jamming,
the original wavelength of 2.40 metres had been modified very
considerably. The following impressive list of wavelengths
current at the beginning of November 1944 was found among
documents brought by General MERTINI’s staff:-
M. M.
Insel A
Insel B
Insel C
Insel D Band Z
- 2,32-2,45
- 2,08-2,24
- 3,00-3,30
- 1,50-1,55
Köthenband gelb/braun
Köthenband gelb/rot
Köthenband Ludwig
Köthenband gelb
Bereich I
- 1,55-1,60
- 1,60-1,65
- 1,65-1,70
- 1,70-1,75
- 1,75-1,80
- 1,80-1,85
- 1,90-2,50
- 1,20-1,90
- 2,50-4,00
Köthenband gelb/grün
Köthenband grün
Köthenband rot
Köthenband braun
Köthenband weiss
Köthenband schwarz
Köthenband blau
Köthenband violett
Köthenband grau
Köthenband blau neu
43. In addition to this formidable list P/W states that in
early 1945 experiments were being made with a Köthen Freya on
about 12 metres. The Köthen Freya with wavelengths of over 4
metres presented a problem to the aerial experts which was
being solved by using Yagi aerials mounted above the normal
aerial mattress. Although it was considered desirable to mount
the aerials at a height above the ground of at least ten times
the wavelength, this was not always possible; for instance the
Yagi aerial of Köthen Blau (4.80 metres) was, according to a
document, to be mounted 30 metres above the ground.
44. Two further new wavelengths known as the Rotschwarz and
Grünschwarz were planned and were to operate on two of the
frequencies used by British Gee in the hope that they would
not be jammed. It was realized that these wavelengths could
only be used when the jamming of Gee by Heinrich transmitters
was not being carried out. The Freyas so equipped were to be
located as far as possible from the positions of the Heinrich
jamming transmitters.
45. In order that these longer wavelengths should not be
compromised, a so-called Kurz Zeit apparatus was built into
the Freyas which allowed transmission of only ten impulses and
prevented more impulses being emitted for a period which could
be set between 2 and 22 seconds. It was considered unlikely
that listening aircraft would be able to tune to these short
interrupted pulses.
46. A document, dated June 1944, in the possession of a
member of General MARTINI's staff, contains a short history of
the jamming experienced by Freya. Extracts from this document
are given below in free translation:
"Jamming by Jamming Transmitters.
"In April 1942 the jamming of Freya on the original 2.40 metre
wavelength was reported.
"On 5th March 1942 the Chef N.V.W. put up a requirement to the
Technisches Amt asking that alternative frequencies for Freya
should be made available, basing his request on the fact that
parts of a Würzburg, from which the exact wavelength could be
determined, had fallen into enemy hands during the Cap
d'Antifer (Bruneval) raid on 27th February 1942. By the end of
1942 the original Freya wavelength was being jammed generally.
"As no steps to provide alternative frequencies in operations
had at that time been taken by the Technisches Amt or by
industry, Ln. Versuchs Regiment Köthen was asked to use its
resources to provide them.
"After about one month, on 15th June 1945, the first Freya
which operated in an unjammed band, the Köthen Grün, was
handed over to a unit for operational use.
"In 1942, Freya on Insel B and Insel C had been demanded from
the industry but they were not delivered until 1943. The Insel
B sets were first available on 23rd February 1943, but shortly
after being used operationally were jammed by the Allies. The
Insel C apparatus was made available on 10th July 1943 and has
been in regular production until the last few months.
"It must be recorded at this point that the first new Insel
was produced by the industry about a year after Köthen had
produced an improvised apparatus. Moreover, the Technisches
Amt and industry were unable to give the Signals branch a
Freya which was not jammed. Assistance had to be sought from
Köthen, who produced Köthen bands which alone enabled the
further operation of Freyas to take place.
"In view of the jamming situation the Chef N.V.W. demanded on
(a) Freya frequencies below 1.90 metres.
(b) A Voll Wismar band which allowed constant frequency
(c) Long waves over 4 metres, with the suggestion that the
Yagi aerial arrays should be used.
"The following comments must be made on the foregoing
(d) The first Freya below 1.90 metres (Flum 41) became
available on 2/7/43.
(e) The first Voll Wismar was delivered in May 1943, but in
spite of this the first mass-produced apparatus was not
available until July 1944, and then only in small
(f) The problem of long-wave Freyas was never taken up by
either the Technisches Amt or by industry. This problem
was solved by the development by Köthen of Yagi
aerials, and these were first built into operational
sets in September 1944.
"Jamming by Window.
"The possibilities of jamming by Window were made quite clear
on 17/3/1943 and a requirement for an anti-jamming device for
all radar apparatus was formulated. Not until 19th June 1944,
that is, one year and three months later, was the Freyalaus,
which had been developed by ZVH, made available by the Chef
"Since it was clear that a change-over to longer waves to
avoid Window was the only possibility available at that time,
the only solution was the use of long-wave apparatus (Yagi
Köthen Grau). With this type of equipment it has been possible
for some months to obtain an early picture free from jamming.
Further Yagi wavelengths were developed and units are being
equipped with them.
"To make recognition of new radar wavelengths impossible for
the enemy, a short transmission system (Kurz Zeit Messung)
described above was formulated as a requirement on 23/9/42. At
the data of writing this has not yet been introduced."
48. The decision to avoid Window by using longer wavelengths
appears to have been taken on the results of some experimental
work. When Window 1.80 metres long was produced against SN2,
Insel C was severely affected, and research work was done on
the susceptibility of different wavelengths to Window of this
length. The diagram produced in Appendix I shows the effect
produced by a standard quantity of 1.80 metre Window at a
range of about 70 km. on various types of Freya.
49. As a result of this experimental work, the Signals staff
realised that it was an advantage to increase the wavelengths
as the intensity of the signal received fell off sharply above
3.80 metres. It was considered impracticable to put a longer
Window into use and as a result the so-called-Köthen bands
were produced.
50. The Germans were unaware that we were dropping very long
Window {rope) at a later date. A certain number of specimens
of this had been picked up and it had been assumed that it had
something to do with meteorological observations.
51. In an interesting publication Funkmessnachrichten No. 19
dated 25th February 1945, it is stated that the C-Insel of
Freya suffered worst from jamming by ground transmitters but
gelb-rot, grün, braun, weiss and grau Köthen bands and the A,
B and D Insel were also jammed at times.
52. Airborne transmitters were beginning to jam the Köthen
grau band, while Köthen braun and D Insel experienced
occasional interference by airborne-electronic jammers. Only
on one occasion had jamming of the Köthen weiss been observed
from the air.
53. The G.A.F. was vitally interested in the Köthen grau band
which was the main stand-by for the early-warning service, and
it was this band and the Köthen blau on 8.80 metres about
which instructions had been given that they were to be
switched on only for very short time in emergency. About 40
Köthen grau equipments were in operation.
54. The range claimed for Freya was 80-120 km., with a range
accuracy of ±300 metres and D/F accuracy with split beam
(A.N.) 1/3°.
55. It is stated in the same document that by February 1945
all Freya equipments, with the exception of some motorised
units, had been fitted with the Freyalaus. A new type of A-J
device, which is however, not described, named the Prüflaus
was at this time being tested on a few sites.

Freya Flamme.
56. A certain number of Freyas in the Insel D band were set
aside for the purpose of triggering off British I.F.F. when
this had been left on in aircraft inadvertently. It was
claimed that, provided the aircraft was flying at a
considerable height, ranges of up to 450 km. had been obtained
with the Freya Flamme. D/F was difficult due to the wide
spacing of the short pulses and no continuous echo beingobtained.
The Germans were aware that six codes were
transmitted by British I.F.F. and believed that they know the
significance of the various identifications.
57. Initially this proved a most useful very long-range early
warning, but the number of aircraft flying with I.F.F. had
been greatly reduced during the last year of the war.

Freya Fahrstuhl.
58. The Freya Fahrstuhl, designed by Köthen, is a Freya with
height—finding facilities obtained by making use of the
reflected ground wave. It was first introduced in early 1943,
but owing to unknown causes, a certain amount of trouble was
experienced and only about eight equipments were in operation
on 1st January 1945. The original requirements were formulated
in 1940 for a Freya type apparatus to give elevation.
59. This set had a range of 220 km. and was used for height
finding by the early—warning service and also as an aid to
Flak if the Würzburg were jammed. The wavelength used was 2.00
metres (Köthen gelb). The Freya Fahrstuhl was originally
intended as an early-warning radar giving height, but the few
produced were largely used to give height to Flak when the
latter's Würzburg was jammed.

60. The history of the development of this apparatus will be
told more fully in the next and final report of this series
which will deal with German Flak radar, for which purpose it
was originally designed.
61. The original Würzburg Insel A had no split beam D/F but
was nevertheless used for early attempts to control night
62. The frequency used by Würzburg A was a single spot
frequency, between 53.0 and 54.2 cm. It was first introduced
in any quantity for raid reporting purposes in the autumn of
1940, when it was used to obtain the height of aircraft
observed on the Freya. Its maximum range was about 25 km.
63. The next type introduced was the Würzburg C with A.N. D/F
facilities and range of 25 km. The first Würzburg C’s came
into service in the summer of 1941. A few were used for
controlling night fighters, but the great majority was used by
Flak. The Würzburg C’s were on fixed frequencies in the band
53.0 to 54.2 cm.
64. The final form of Würzburg, the D, had still only a 25
km. range operationally, but was a general improvement over
the C with split D/F facilities giving an accuracy of ± ½° and
range accuracy of ±50 metres. It was introduced in the autumn
of 1941 believed to have been used for Flak purposes only.
65. The original sets were in the frequency band known as
Insel A 53.0 - 54.2 cm but later a B band from 56.7 to 58.0
and a C band from 62.3 to 63.8 were introduced.
66. Finally a Würzburg was manufactured with wide band
aerials using the Urechse equipment which allowed any
wavelength between 53.0 and 63.8 cm. to be used. The Urechse
transmitter was being generally introduced in the spring of

Würzburg Riese.
67. The Würzburg Riese was introduced in 1941, and from the
beginning was mainly used for the close control of night
fighters on the Himmelbett system. In all, 452 sets were in
operation on 1st January 1945. A few sets were used for
providing the Gross Batterien, situated at Berlin and other
places, with information for their anti-aircraft operations,
but these were of the Riese G (Gustav) type with Freya aerials
incorporated in the paraboloid, so that a 50° wide search beam
was provided as well as the 13° main beam on 50 cm.
68. The wavelength used for the Freya section of the Riese G
was originally 2.20 Metres, but wavelengths of 1.80 metres and
1.70 metres were also introduced, and it was intended to use
1.60 metres in the future. The Würzburg section of the Riese
used the A and B Insel of the Würzburg bands, namely 53.0 -
54.2 cm. and 56.7 - 58.0 cm. The range of the Würzburg Riese
was about 70 km. and its range accuracy was of the order of
±50 metres.
69. Some ten of the sets used for Flak were provided with
Voll Wismar using the Schwarz Echse transmitter on a new
wavelength of 1.50 metres.
70. The additional Freya wavelength was found to be
particularly valuable against U.S. day bombers, which usually
only jammed the Würzburg 50-60 cm. band and left the Freya
band unjammed.

71. The original purpose for which Wassermann was introduced
was to obtain a more powerful early warning radar with a
greater range than Freya, and it was therefore the G.A.F.
equivalent of the novel Mammut. Three main types of Wassermann
were produced, the L, S and M.
72. The Wassermann L (Leicht = light) was produced by Gema
and was said to have a range of 200 km., an accuracy in D/F of
± ½° and in range of ±5 km. The first set came into use about
the summer of 1942; two types were manufactured, namely L.I,
on 2.40 metres and L.II on 2.01-2.27 metres, in which spot
frequencies (Streuwellen) at 15 mc/s intervals were available.
About 25 of these were built. They were constructed as lightly
as possible so that they would be transportable, which was
considered specially important for the Balkans and in Norway.
It was estimated that they took about 3-4 weeks to erect. They
had, however, a disadvantage that in strong winds the whole
tower was apt to be blown over.
73. The Wassermann S (Schwer = heavy) was also constructed by
Gema and its accuracy was comparable with the L, except that
ranges of 300 km. were obtained. The first equipment was
erected towards the end of 1942 and in all some ten became
operational. The first seven sets erected (S.1 to S.7) used
wavelengths of 2.40 or 2.46 metres. These numbered S.8 to 10
used 2.36 metres, 2.34 metres and 2.29 metres. These sets took
something over 4 months to build, but they were at least more
robust than the Wassermann L.
74. The final form of Wassermann, the M. (Mittel =
intermediate) was designed by Siemens. Its accuracy in D/F and
range was about the same as the other two types but a maximum
range of about 220 km. was obtained.
75. The first types introduced were the M.I and M.II in the
autumn of 1943. Both used frequencies in the 2.01-2.20 metre
band but the M.II allowed different frequencies within this
band to be used on the Wismar principle.
76. The M.III used the 1.20-1.90 metre band, and was of the
wide band Voll Wismar type but only two sets were built, as it
was succeeded in the spring of 1944 by the M.IV which gave
wide-band facilities from 1.90-2.50 metres. Some twelve M.IV.
were in operational use by January 1945, and more were being
77. The latest form of Wassermann was to be the M.V. which
was a wide band equipment working on 2.50-4 metres, of which
one experimental set had been set up on the Baltic coast.
78. Since about the beginning of 1944 an electrical
compensating arrangement had been built into the Wassermann
which allowed the beam to be swung in elevation, and an
elevation of about 15° could be obtained. The A-J device
Wasserfloh with Doppler effect was fitted first towards the
end of 1944.
79. Generally speaking the Wassermann was a disappointment.
Production of Elefant was postponed as the original estimate
of Wassermann's range, as late as autumn 1943, was that it
would give 400 km. coverage. Wassermann never succeeded in
giving coverage much over 200 km.

80. This coastal radar equipment which was known to the
Allies as the "Hoarding" was really a Naval coast-watching
radar of which some 8-10 specimens were operated by the
Luftwaffe. It had the advantage that the polar lobe was well
beamed - more beamed than the Wassermann - and, therefore, it
was not very susceptible to jamming but it took about 8 months
to erect and was costly and unvieldy. The comparatively narrow
lobe scanned electrically by means of a phase shifter, termed
a compensator. The wavelength used was the original Freya band
2.40 metres and the range achieved some 300 km. No height
finding was available.

81. The Elefant, sometimes referred to as See-Elefant was
produced by the Reichspost and was designed in part by Ober
Postrat Dr. SCHOLZ. At the end of the war three equipments of
this type had been built and a further three were in course of
erection. The wavelength used was comparatively long, in
conformity with policy of escaping the effect of Window by
increasing the wavelength. Of the three sets built, two were
in the 7.90-8.80 metres band, and the remaining one in the
band from 10.70-12 metres.
82. A D/F accuracy of 1° was obtained and range accuracy of
±4 km. The first set was created in the summer of 1942. But it
underwent constant improvement and its form was not finalised
until 1944. In November 1943 the Technisches Amt refused
definitely to sanction the large-scale introduction of Elefant
as although a range of 400 km. was obtained similar results
were expected (but never obtained) from the Wassermann. A few
were, however, built by Köthen in the field.
83. In order to prevent the long wavelength from being
compromised, the Elefant was only used for short periods and
when the air situation was not clear to the ear1y-warning
service. This was the more important as it was realised that
Elefant could easily be jammed. The normal array consisted of
two 100 metres high towers.

84. One of the present P/W believed that experiments were
being carried out with an early warning set on a wavelength of
between 18 and 20 metres which was to be called Heidelberg. He
understands that jamming interference was encountered, as the
set operated on the frequency band used by W/T traffic, and
for this reason the project was dropped. P/W stated that it
was hoped to obtain very great ranges, as the waves would
conform to the earth's curvature. There may, however, be some
confusion in his mind with the Klein Heidelberg system
described below.

Klein Heidelberg.
85. The name Klein Heidelberg was given to a system utilising
reflections from aircraft of the pulses emitted by British
radar stations or by distant German stations. Strictly
speaking, therefore, it was not a radar set at all.
86. The results obtained were satisfactory at the three
stations used, but at the time of its invention by Ober
Postrat SCHOLZ, in 1941, it was not regarded as of particular
importance, as their radar was not being jammed.
87. In 1944, when jamming became serious, the Klein
Heidelberg system proved of great value. Its D/F was poor but
range was adequate for early warning information.
88. It was noticed in October 1944 that our 25 cycle CH
stations had started to change their p.r.f. but a radio
locking system was improvised within six weeks and thereafter
no trouble was experienced. Tests were made to utilise the
Gee pulse sources, but the system worked adequately with CH
and the experiments were not pursued.
89. When he was interrogated on this matter Dr. SCHOLZ stated
that he understood that the results obtained at the Römö
station were surprisingly good, despite the great distance
from Great Britain.

90. The Würzmann was the name given to an experimental
coastal set which was to be used for the location of low
flying aircraft. According to P/W, it was a Jagdschloss
Michael B aerial array set up on end. The aerial array of the
Jagdschloss Michael B consisted of a double row of 18 Würzburg
mirrors and measures not less than 56 metres x 7 metres.
91. This gigantic erection was mounted so that the electric
centre of gravity was 50 metres above sea level and produced,
in fact, a Würzburg beam which was very narrow in azimuth.
With its aid it was claimed that aircraft flying at 0 feet
could be seen at a range of 20 km.

92. Tiefentwiel was the code name applied to an aerial array
placed high above ground using the Hohentwiel A.S.V. set with
the intention of detecting low-flying aircraft coming in over
the sea. No details of the aerial array or method of operation
were known but it was stated that the Tiefentwiel achieved as
good results as the Würzmann, namely a range of about 30 km.

Hohentwiel Boden.
93. Funkmessnachrichten publication No. 19 announced the
introduction of a short-range highly-mobile early-warning
radar called Hohentwiel Boden which could be erected in 15
minutes. The set consisted essentially of the Hohentwiel
A.S.V. set with an aerial array mounted on the top of a 10'
high mast. This improvisation was carried out by the Ln.
Versuchs Regiment Köthen, who stated that individual targets
could be seen at a range of 30-35 km. and formations at 60-70
km. It was to be used in the front line to give advance
warning of raids.

94. Some time in 1943 the firm of Lorenz produced an idea for
a P.P.I. presentation for early warning to which they gave the
code name "Propeller". This set relied on extremely rapid
rotation of the aerials and used a wavelength of about 50 cm.
95. Just before the set was officially demonstrated to the
G.A.F. it exploded. All the apparatus was lost and the project
was abandoned.
Jagdschloss F.
96. The first type of early-warning radar set giving
panoramic display which come into operation in usually
referred to as the Jagdschloss, although it’s official
designation is Jagdschloss F, to distinguish it from later
types, such as the Michael B and Z. It was produced by the
firm of Siemens and was first used in operations in early
1944. About 65 Jagdschloss F equipments had been manufactured
by the end of the war.
97. Equipments No. 1 to 62 were of the Voll Wismar type using
wide band aerials and covering the band 1.90-2.20 metres. From
63 onwards the frequency band to be covered was 1.20-1.90
metres. A document mentions Jagdschloss lang (=long) with a
wavelength of 8.0-10 metres. No information about this has
been obtained.
98. These sets were used exclusively by the early-warning
service and gave a range of about 100 km. with a D/F accuracy
of 1° and a range accuracy of 4.5 km.
99. The range accuracy depended largely on the presentation
on the 40 cm. P.P.I. tube. At 100 km. the area of error was
stated to be 5 x 5 km. but Köthen was attempting to improve
the presentation so that blips could be read to a greater
accuracy by introducing electrical range rings.
100. Another trouble that was being experienced in February
1945 was that the 50 cycle frequency at the national electric
grid affected the presentation so that the blips which should
have appeared as small arcs actually appeared as an arc with a
wavy out-line.
101. The P.P.I. tubes produced by Siemens were being modified
to avoid this imperfection while the Fernseh A.G., who also
produced tubes for Jagdschloss, were working on the problem.
It was believed that a new type of "Tonfrequenz" cable would
be necessary. Particular attention was being paid to this
point because of the difficulties in reading the tube caused
by window.
102. According to a document a new type of valve called the
Nullode was being introduced at this period to replace the
8D.6 diode in the Simultan unit.
103. It was proposed to introduce a selecting switch, by
means of which three alternative pictures could be produced on
the P.P.I. tube. The first picture showed all blips present on
the tube, the second position allowed the I.F.F. to be
switched in, while the third was a purely I.F.F. picture in
which only friendly aircraft with I.F.F. operating came up.
104. The I.F.F. problem had not been fully solved and it is
stated in a document that a separate FuGe control set is
necessary to assist in obtaining unequivocal identifications.
105. In this same document mention is made of the Münchhausen
system which was to use coloured photographic films to
distinguish between Windows and moving targets; stationery
targets would appear on the film as dark spots while moving
aircraft would appear as spots with red and blue edges in the
direction of movement. This system had been worked out at
Werneuchen and in February 1945 the first apparatus was in use
with a Jagdschloss equipment in the field. The film, however,
took between one and two minutes to develop.
106. Further difficulties in the form of dead zones were
being encountered with Jagdschloss and it is suggested in
Funkmessnachrichten publication No. 19 that a wire netting
surface with a radius of 50-60 metres should be built round
the Jagdschloss in order to get rid of the lower dead zone and
to aid in increasing the range against high flying aircraft.
It is stated that one ton of iron wire netting necessary for
each site.
107. According to P/W the electrical jamming of Jagdschloss
was never very severe, particularly as it had Voll Wismar. The
fact that it was causing trouble was, however, proved by the
fact that in Funkmessnachrichten publication No. 19 it is
stated that a number of special cameras had been provided and
were in use at various Jagdschloss sites to take pictures of
the type of jamming encountered in order to ascertain what
measures could be undertaken against jamming.
108. A so-called electric lens was to be used as a means of
seeing through Window. This was an arrangement whereby a
magnification of between 2 and 3 times natural size could be
obtained of a circular area of the picture. The area which
could be magnified could be chosen but was limited to circles
whose circumference passed through the centre of the tube, but
did not reach the edge of the 40 cm. P.P.I. tube.
Jagdschloss Michael B.
109. A ponderous aerial array of two rows of eighteen
Würzburg mirrors measuring 56 metres long x 7 metres high was
used in the Würzmann experimental early-warning radar, and
formed the serial array for Jagdschloss Michael B with the
array in a horizontal position. The wavelength employed, was
that of a Voll Wismar 53.0-63.8 cm.
110. By means of this aerial a beam of ½° horizontal width
was obtained and a range of about as much as 250 km on single
aircraft was expected. It was also expected that the narrowbeaming
of Michael B would be of great assistance in avoiding
Window. The dead zones were to be overcome by switching the
frequency to another wavelength in the Voll Wismar band II,
which was believed to run from 50-60 cm. The first set was to
be ready in April 1945.

Forsthaus F.
111. This apparatus was designed by Telefunken to fulfil the
same purpose as the Jagdschloss Michael B using the so-called
Euklid 25-29 cm. waveband employed by the Navy. Once more a
very long aerial array 48 metres long and about 8 metres high
was used, employing a cylindrical paraboloid. A wave guide
antenna (Hohlraumstrahler) was placed along the focal line
with a second and a third wave guide parallel to it above and
below respectively. The object of these two supplementary wave
guide aerials was to provide displaced beams and so avoid the
dead zones. A range of 220 km. was expected against single
aircraft but no details were available as to whether it had
come into operational use.

Forsthaus KF.
112. In order to introduce as rapidly as possible a panoramic
early-warning radar in the West on a hitherto unused
wavelength, a smaller form of the Forsthaus F called the KF
was to be introduced while the F was being completed. It was
planned so that it could be used on a railway wagon; the
revolving aerial array was only 24 metres long and it was
expected to give a range of 120 km. The wavelength and
electrical circuits used were exactly the same as in the

Forsthaus F.
Dreh Freya.
113. This set, which was also known as Freya Panorama, was
first introduced in June 1944. It consisted of a Freya aerial
of the Breitband type working in Bereich I (1.90-2.50), the
frequency of which could be adjusted at will. The aerial was
so built that it rotated through 360° and gave a remote
panoramic presentation. About 20 equipments were in use in
January 1945. The range claimed for it was only about 100 km.

114. This apparatus, which was produced by Siemens, gave a
panoramic P.P.I. display of the German I.F.F. responses, using
24 metre or 36 metre rotating aerials. The wavelength employed
was 2.40 metres and it was planned, with its aid, to trigger
off the FuGe 25A. In this way friendly fighters were to be
controlled from the ground at ranges up to about 300 km. It
was fully realised that if the FuGe 25A frequency was ever
jammed the Jagdhütte would be useless, but it was not
considered likely that the Allies would attempt to jam it.
115. On the 1st January 1945 the first Jagdhütte equipment
was being erected, and it was expected that production would
amount to two per month thereafter. At the end of the war
about 8-10 were being built, but there is no information as to
how successfully they were employed.

116. Jagdwagen was designed as a mobile Panoramic radar to
control fighterAs at close ranges immediately behind the front.
It was a project of the firm of Lorenz. The aerials were
considerably smaller than the Jagdhütte, the array being only
8 metres long. The aerial array was to be mounted on the
Kumbach stand as used in the Egerland Flak set. The frequency
bend used was that of the A.S.V. set Hohentwiel namely 53-59
117. The horizontal beaming was of the same order as that in
the full Jagdschloss F, namely about 6°, and ranges claimed
for it were of the order of 40-60 km. for medium heights. A
small P.P.I. tube of about 15 cm. diameter was used.
118. In February 1945 the first sets were being tried out at
Werneuchen but it was hoped to produce the Jagdwagen, in
series, as a fully mobile panoramic set operated by a
motorised company to install them on aerodromes so that a
picture of the local air position could easily be obtained.

Jagdschloss Z.
114. The Jagdschloss Z was the centimetric form of
Jagdschloss, which was in development by Siemens; the rotating
aerials were to be about 24 metres long. These sets were to
give an extremely narrow beam and so offer protection against
jamming. The range expected was of the order of 100 km., and
although the first experimental equipment had been built it
was not expected that sets would came into operational use
until the autumn of 1945.

Forsthaus Z.
120. The Forsthaus Z was another form of 9 cm. panoramic for
early warning, which was produced by the firm of Telefunken.
It differed from Jagdschloss Z mainly in the design of aerials
and was about in the same stage of production. No information
could be given as to the advantages or disadvantage possessed
by Jagdschloss Z.
NOTE: One of the documents brought to England by General
MARTINI’s staff contained a list of the frequency
coverages mentioned in this report, and is reproduced
in Appendix II."

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German Radio Countermeasures

"SECRET A. D. I. (K) Report No. 380/1945


German Radio Countermeasures.
1. This report is the ninth of the series dealing with
radio and radar equipment in the Luftwaffe. The present
information was mainly obtained from Dr. Ingenieur SCHOLZ, a
civilian employee of the Reichspost Zentrale who was in
charge of a sub-section of Abteilung 6 of the
Generalnachrichtenführer dealing with the problem of RCM
(radio countermeasures).
2. Interrogation of this man has been supported by
information gained from other members of General MARTINI's
staff and by a number of relevant documents of recent date in
possession of the General's Chief of Staff. Some useful
additional help was given by two engineers who had recently
been engaged in testing ground and airborne jamming equipment
at the G.A.F. research establishment at Werneuchen.
3. The radio countermeasures used by the Germans have been
treated in this report under four headings, the first being a
brief historical account of their employment, and the other
three dealing in turn with RCM against communications, metric
radar and centimetre radar. The types of jamming transmitters
referred to by name, or of which a mention has been found in
documents, are listed in alphabetical order and their
functions briefly described in Appendix I to this report.

4. At the beginning of the war the G.A.F. High Command was
not radio minded; GOERING in particular has been frequently
accused by his underlings of paying no attention to technical
matters. In the opinion of General MARTINI's staff, the vital
importance of radio warfare and radio countermeasures was
only truly appreciated by the General Staff towards the end
of 1944. Those responsible for German jamming, therefore, had
great difficulty in obtaining permission to use the
countermeasures to the extent that they could have wished.
5. The countermeasure organisation relied in the first
place on the German "Y" service, which formed Abteilung 3 of
General MARTINI's staff, to give advance information of new
radio activities, and for this purpose it employed a staff of
expert radio engineers whose task was to identify and explain
any new frequencies or types of transmissions received. If,
however, novel features in a monitored transmission were
observed and could not be explained, a commission for the
investigation of the particular subject was set up. This
commission was composed of representatives of the "Y" service
and of the Development (E) departments of the R.L.M.,
representatives of the research (F) department of the R.L.M.,
and such experts from the leading firms as had special
experience in the field of radio which was thought to be in
6. Evidence collected by listening, though it could be very
valuable as intelligence, did not necessarily tell the whole
story or indicate the most suitable form of countermeasures.
As far as airborne equipment was concerned, statements made
by prisoners of war often helped to fill out the details and
the capture of equipment and its identification with the new
transmission was of great value, even if the equipment was
severely damaged.
7. Intelligence information from the above three sources
could usually be pieced together to tell the whole story, so
that decisions could be taken as to whether radio
countermeasures were required.
8. The Germans relied very largely on the laboratories and
experience of the Reichspost Zentrale (RPZ) to solve the
technical problem of how and with what equipment to jam, and
they obtained for the duration of the war the loan of an
engineer of that organisation (the present P/W) who was put in
charge of RCM and carried out liaison with RPZ to this end.

9. The decision to jam a particular type of transmission
rested very largely with General MARTINI and was often taken
despite the protests of the "Y" service section of his staff,
who were interested professionally in monitoring all
transmissions. Particularly in the case of R/T, the "Y"
service insisted that more strategic and tactical information
could be obtained by D/F’ing enemy transmissions than any
tactical advantage which might be gained by jamming them.
10. As an instance of the extent to which the decision lay
with General MARTINI the following case was quoted: In 1942
Allied night fighters were becoming a nuisance in the
Mediterranean area but General KESSELRING had to ask General
MARTINI’s permission to jam their ground-to-air R/T control in
his theatre of operations and only then could the
countermeasures be undertaken.
11. The first German radio countermeasures were instituted in
September 1940 during the day bombing raids of the Battle of
Britain and were directed against British radar operations in
the Channel. The first and most important site used was that
at Mont Couple behind Calais were, by the end of the war, a
battery of some 35 jammers had been set up.
12. Radio countermeasures against Gee were put in hand in the
summer of 1942 and at about this same time the first attempts
were made to jam A.S.V. in the Channel. From this time on, the
countermeasure warfare increased and consideration was given
to jamming all types of new radar devices.
13. In about 1943 it was realised that countermeasures might
well be called for on every wavelength, and Dr. SCHOLZ put up
a requirement to the Reichspost Zentrale (RPZ) laboratories
for a series of jammers to be designed for covering all
wavelengths from 50 cm. upwards. These jamming transmitters
were designed in the Potsdam RPZ laboratories, and
improvements were constantly being incorporated in them so
that if there was a sudden call for countermeasures on an as
yet unused frequency, a practical design was available and
apparatus could be built at short notice.
14. As a result of this policy new countermeasures could be
put in hands quickly, but in practice they usually took
considerably longer to organise than might theoretically be
expected because the ground crews had to be trained in their
use. Dr. SCHOLZ stated that with a few exceptions these ground
crews were of second-rate material and it was frequently a
matter of weeks before they were sufficiently well-trained for
the countermeasures to become effective.

15. With the possible exception of communications between land
and convoys, P/W believed that no attempt was made to jam
Allied W/T communications on the ground. Listening to them was
considered to be of the greatest strategic intelligence value
and little or no tactical object was served by jamming.
16. Radio countermeasures against the B.B.C. news service were
in the hands of civilian authorities, and the G.A.F. had
nothing whatsoever to do with them. Dr. MEINEL of the
Reichspost was believed to have been responsible for the
production of the type of jamming modulation which was
generally used.

17. The question of jamming Allied ground-to-air and air-toair
R/T was one of the points most strongly disputed between
the "Y"-service and the operational side of the G.A.F. The
"Y"-service maintained that by listening to and D/F’ing
traffic, both strategic and tactical intelligence was obtained
and that it was frequently their best source of early warning
of attack by aircraft; as a result relatively few attempts
were made to jam Allied R/T.
18. In the case of German raids on England the signals staff
agreed that there was an advantage in jamming British R/T
communications; this point arose when the possibilities of
Mark IV A.I. were first realised early in 1941. The question
of how to undertake countermeasures against British A.I. was
discussed and the weak point of the system was held to be the
R/T link from ground to air, because it appeared to be
essential for the night fighter to be brought within
2 km. of the bomber before contact could be made.
19. The Reichspost Zentrale built an airborne R/T jammer set
which was given the name of Karuso and was intended to prevent
R/T being heard by the night fighter when the latter was
within 3 km of its target. Within eight weeks the first Karuso
equipment was ready and a total of 100 were built. With the
cessation of the bombing of England in about May 1941, the
majority arrived too late and Karuso was only used once in a
limited number of aircraft in a bombing operation when, P/W
believed, Plymouth was the target.
20. When in 1943 trouble with British night fighters was again
being experienced in the Mediterranean, the Karuso sets were
sent down to that theatre. There, however, the range of
British A.I. was found to be about 4 km. instead of 2 km., so
that the power output of Karuso had to be boosted to give it a
range of 5 km.
21. The method employed was barrage jamming using two bands
(100 - 110 mc/s and 110 - 120 mc/s) with mechanical condensertuned
sweep through the band. There was not room for two
transmitters in one aircraft so only half the band could be
covered in any one German bomber. Karuso III, a later
improvement, was to be capable of being tuned through 100 -
150 mc/s band but so far as is known, it was not put into use.
22. Subsequent tests of Karuso indicated that it had
insufficient range, and by December 1944 the Starnberg, which
was developed in 1940 by D.V.L. as a jammer against radar, had
also been tried out but was likewise considered inefficient. A
new set named Nervtöter was under development but never came
into operational use.
23. It was decided that the jamming of R/T would be of value
against air activity when the invasion took place and prior to
D-Day some 50 or 60 modified Karl II jammers had been formed
into a Stördorf (= jamming village) and assembled at a site on
the Channel coast near Dieppe. With this assembly of jammers,
all possible frequencies in the 100 - 150 mc/s R/T band could
be covered.
24. A few days before the invasion the site was carpet bombed
by the Americans and although the jammers had been somewhat
dispersed, 90 of them had their aerials damaged or were put
out of action. There was some delay in bringing up reserve
motorised units and the invasion took place before they
reached the Channel coast. As a result, no countermeasures
against fighter R/T took place during the invasion.
25. In November 1944 a limited amount of jamming of fighter
R/T in the 70 - 100 mc/s band was carried out on the western
front by motorised units and from a few fixed sites. These
countermeasures were on a restricted scale, owing to lack of
apparatus, but it was hoped to interfere with Allied ground
control of fighters and fighter R/T.

26. During defensive operations over the Reich against Allied
aircraft, countermeasures were very rarely used owing to the
insistence of the "Y"-service on the value of D/F’ing
transmissions, particularly as the German early warning radar
was heavily jammed. Early in 1945, however, it was planned to
create four jamming villages (Stördorf) each with ten Karl
transmitters in order to jam R/T during raids over German
territory. The use of airborne jammers to carry out the same
task had been considered but it was felt that airborne jamming
was less rational than jamming from ground stations because
the frequencies had to be constantly monitored.
27. By the end of the war a new jamming transmitter called the
Feuerland had been developed by Blaupunkt. This allowed noise
modulation to be used in addition to the more generally used
Reichspost modulation. A few sets were sent up to the Holstein
area just before the capitulation, but it was believed that
they had never been used in operations.
28. The standard type of modulation which had been developed
by Reichspost consisted of a number of "Kipp" frequencies -
sharp triangular pulses produced by blocking oscillators -
superimposed on the carrier wave. Tests of its effectiveness
at audio frequencies were carried out early in the war and a
statistical analysis of them seemed to show that it was the
most effective modulation against R/T.

29. The airborne FuGe.10 was being developed for use as a
jamming transmitter against the 3 - 6 mc/s band R/T used by
the Russian Air Force. This apparatus never came into
operational use.

30. It was in August or September 1940 during the Battle of
Britain that the first German countermeasures were directed
against British ground radar. The site at Mont Couple behind
Calais was used at first, but was gradually extended to a
chain of ground jammers along the whole Channel coast, and
ultimately there were sufficient to have every identified
British ground radar station covered by at least one suitable
31. In 1940 the stations jammed were those in the 20 - 30 mc/s
and 50 – 90 mc/s bands. Both ground stations and airborne
apparatus carried in Ju.52's were used. By 1941 a chain of
Karl jammers which also covered the 200 mc/s band had been set
up along the whole coast.
32. During the initial period, various efforts were made to
spoof our early warning radar. The first of these was the
brain-child of Dr. SCHOLZ and was tried out in 1940.
33. Pulses radiated by one of our C.H. stations were picked up
on the ground and re-transmitted on a different frequency to
an aircraft flying some way behind the Channel coast. The
aircraft re-transmitted the original radar pulse on the C.H.
frequency, but a slightly different phasing, so that a phoney
blip located over the Channel was received. Owing to the ease
with which this phoney blip could be D/F'd and the spoof
immediately revealed by a second station, this method was soon
34. About the beginning of 1941 a special experimental
equipment called the Garmisch Partenkirchen, which produced no
less than five different phasings and five phony blips, was
tried out. For the same reason this was not much used in

How the "S & G" Got Through.
35. The first big operation on which the jamming chain against
British radar ground stations was used was on the occasion of
the passage through the Channel of the Scharnhorst and
Gneisenau in February 1942. A few days prior to the operation
Dr. SCHOLZ was specially brought from Berlin to supervise it.
36. The radar cover of our C.H. and C.H.L. had been carefully
plotted and it was ascertained that the ships would come
within its range as they passed off Fecamp, where they were
due at 10 a.m. At that hour every available jammer was
switched on. The fact that the ships passed through unscathed
was, in P/W's opinion, the best proof of the effectiveness of
the German countermeasures. P/W was not aware that we had
either decimetre or centimetre radar in operation at this

Siege of Malta.
37. In July 1942 P/W was sent to Sicily to take charge of an
intensive jamming programme which he suspected was to be the
precursor of the invasion of Malta, although he was never told
so officially. The first four Karl jammers on 193 mc/s were
brought into service in the neighbourhood of Noto en 3rd July
1942 and the number was later increased to eight, to cover
both A.I. and ground stations. They were beamed on to the
sites at Malta. These transmitters were half kilowatt, C.W.
amplitude-modulated at 100 c.p.s. using an unsmoothed HT
supply, plus a modulation of 150 - 200 kc/s. The reason for
the amplitude modulation being unsmoothed was that there was a
shortage of high-voltage smoothing condensers.
38. After a time it was observed that we had adopted frequency
changes. The German jammers were however, controlled by
monitoring receivers on sites so arranged that the jamming
signals and the original radar signals could be seen side by
side on a C.R. tube; this enabled the frequency change to be
followed within a few seconds. A great aid to them in
following and preparing for these changes was that new
frequencies were invariably tried out during the day from
Malta and the monitoring service could warn the jamming
operators of frequencies likely to be employed.
39. It was noticed that signals on the 50 - 80 mc/s frequency
were switched on during a raid and it was suspected that they
were due to the height-finding equipment of the radar station
controlling our night fighter which seemed to operate in a
similar fashion to the German Würzburg. This opinion was
confirmed when "Y" service heard a ground station say that
they could give the range of the bandits but that height
measurements were not yet available.
40. To jam the "height-finding" frequencies a Ju.52 fitted
with eight jammers covering the 50 - 80 mc/s band was brought
down to Catania. An hour before a raiding force became
airborne this aircraft left Catania to patrol half way between
Sicily and Malta and jam this band.
41. After P/W left, jamming was also carried out on the 42
mc/s band with the same type of Karl ground transmitter as was
used for other frequencies.
Modulation of Jammers.
42. When jamming out ground radar, H.F. modulation was always
preferred to noise modulation since the equipment necessary to
produce a given effect with noise modulation was much more
extensive than for H.F. modulation, and in particular a large
number of high-power valves was needed. The greater efficiency
of noise modulation was not considered sufficient to warrant
the extra power and extra equipment needed. It was also
thought unlikely that H.F. modulation could be filtered out of
the radar receiver without severe deterioration of the

Düppel (Window).
43. The idea of using window to spoof ground radar had
occurred to the Germans in 1941 and a series of experiments
was carried out in great secrecy over the Baltic in February
1943 (See A.D.I.(K) 334/1945 Part, IV). Very careful
arrangements were made to ensure that the wind was in the
right direction so that the window strips would fall into the
sea and not in Sweden, or even on German occupied territory.
44. The effect of window was observed on all types of German
ground radar deployed along the Baltic coast, and its efficacy
as a countermeasure was realised. The German codename for
Window was "Düppel" - a word with a very similar pronunciation
to the German word "Dipol" (= dipole), indicating the function
of the metal strips.
45. The Signals Staff realised that Düppel was a two edge
weapon and although its development was completed sometime in
1942, and a certain quantity was manufactured, no use was made
of it for fear of Allied retaliation.
46. The whole project was, in fact, kept so secret, that only
a very few high officers and technical experts in the G.A.F.
were aware of the scheme. So closely was the secret of Düppel
guarded that the scientists were not even allowed to carry out
research work to discover what anti-window measures could be
applied to the various types of German radar.
47. Although the Germans were free to employ window as a
countermeasure over this country after its first use by the July 1943, it was realised by the Signals Staff that
they had never used it to such good effect as the Allies.
48. The reason was that the small German bomber aircraft like
the Ju.88 could only carry a very limited quantity and
therefore could not produce a real window cloud. They
therefore decided to drop small quantities scattered over a
wide area in the hope of deceiving the night fighters and of
producing the impression that a larger number of aircraft was
engaged on a certain raid as well as in the hope that ground
controllers might vector night fighters on to a window cloud
instead of on to an aircraft.

Final Policy against Early Warning Radar.
49. The general policy followed by the G.A.F. at the end of
the war with regard to the countermeasures against early
warning metric radar appear to be summarised in a document
dated December 1944, which states that the use of ground
jammers against all ground radar is, in principle,
particularly desirable during German bomber raids on enemy
territory, but that there is no advantage in using airborne
jammers because the frequency of the ground radar has to be
constantly monitored and followed.
50. This principle was not strictly adhered to because an
airborne jammer for the 170 - 220 mc/s band named Kettenhund
was used to a small extent in raids on the South-West of
England in May 1944 (sec A.D.I.(K) 321/1944) but it was not
considered to be very effective.
51. Some attempt was being made to develop a noise-modulated
airborne transmitter named Wolke but it was never used

52. The first attempts to jam A.S.V. were made in the Channel
in the summer of 1942. During the preparations for the
proposed invasion of Malta it was found that reception of
British A.S.V. transmissions was obtained at extraordinary
ranges in the Mediterranean area. This was ascribed largely to
the fact that the receivers were placed as high as possible -
in some cases 3,000 foot above sea level - and attempts were
made to jam A.S.V. by using Karl transmitters placed near them
on high points of the coast of Sicily, Greece and Crete.
53. At about this time a Sonderkommando KOCH was formed and
based at Athens-Kalamaki. Its duties were to monitor and jam
A.S.V. and it was thought they used the Kobold airborne
transmitter with a frequency range of 160 - 200 mc/s. It had
the disadvantage that it could only be built into large
aircraft and some doubts arose as to whether it was very
54. Up to the of the war, the Bari ground jammers continued to
be employed against A.S.V., particularly along the length of
the Adriatic and along the Norwegian coast at points where
German coastal convoys obtained no cover from islands lying
off the coast.
55. In mid-1943 U-boats leaving Brest were suffering a serious
increase in losses owing, it was thought, to the use of our
A.S.V. a Sonderkommando Rastädter was formed with a few He.111
and Ju.88 aircraft for the purpose of listening to British
A.S.V. on metric and centimetric wavelengths and determining
what type of radar was being used with such effect (see
A.D.I.(K) 38/1944). These aircraft carried, amongst other
receivers, both Naxos and Korfu. The net conclusion reached as
a result of these investigations was that Coastal Command was
using a centimetric frequency (presumably H2S) for which the
Germans had no jamming transmitter.
56. The Allied attacks on U-boats took place so far from the
coast that ground jamming of A.S.V. on metric wavelength was
impossible and too many aircraft were needed to carry out
efficient airborne jamming. It was feared, too, that if
airborne jamming were carried cut, it would only attract
A.S.V.-equipped aircraft or surface vessels to the vicinity,
and be a proof that U-boats were about.
57. Warning receivers were therefore installed in U-boats. The
first of these - Metox - was used against metric A.S.V. It
suffered from the disadvantage that its local oscillator
radiated strongly, and it was suspected that we could home on
to this radiation from 100 km.; the Samos receiver later
replaced Metox. A form of Naxos was introduced to provide
warning against 9 cm. A.S.V. and was used up to the end of the

58. The weak link in the British night fighter organisation
was, as already mentioned, considered to be the R/T
communication; the airborne jamming of British A.I. itself by
German bombers or special R.C.M. aircraft was not considered a
practical measure because it was believed that British night
fighters would be able to home on to the jamming aircraft and
severe losses were therefore to be expected.
59. No intentional jamming of Mark IV A.I. was ever carried
out from the air or from the ground, although it was
considered possible that Karl jammers against G.C.I. and
harmonics of the Heinrich transmitter against Gee, and
possibly of all transmitters jamming Oboe and C.H., may have
had some effect.
60. In this connection P/W stated that it was extremely
convenient for the Germans that we had so many equipment
working on such a restricted frequency band in the 200 mc/s
region. This fact has eased their jamming problem very

61. The value of Gee system of navigation referred to by the
Germans as Hyperbel, is that it allows an aircraft to navigate
by a radar method without transmitting any signals which could
be used to D/F the raider from the ground. This threat was
realised by the Germans in March 1942 when the existence and
method of operation of the system was first discovered, but
the decision to jam Gee was not taken until August 1942.
62. A jamming transmitter was hurriedly improvised out of the
standard A.S. ground transmitter used for R/T traffic with the
FuGe.16. This was modulated with the standard "Mont Couple"
modulation at 150 - 200 kc/s. Prior to this makeshift coming
into use, a certain Dr. MÖGEL had experimented locally with
jamming transmitters but these only operated for a short time
and no details are known of them.
63. An order for a large number of suitable jamming
transmitters for countering Gee was placed in August 1942 and
the first of these - 1/2kw. Heinrich - went into service in
November 1942. As the Heinrich transmitters became available
in quantity they were deployed all over Germany and by the end
of the war some 270 were in operation against Gee.
64. Estimates of the effectiveness of jamming by the deployed
Heinrich transmitters were obtained by flying captured Gee
equipment and by questioning British P/W. The conclusion
reached was that before the invasion the Gee chains were of no
use further East than 4°.
65. After the invasion the situation changed, and in August
1944 a so-called Stördorf (= jamming village) was set up on
the Feldberg in the Taunus area and controlled and run by the
Reichspost Zentrale. Installation began in August and in
September the first equipment came into use.
66. The Gee countermeasures from the Feldberg site were of a
different type. In addition to a number of normal Heinrich
transmitters, three new types of much greater power were used.
These were Feuerzange, a very powerful pulse transmitter with
a peak power of 1 megawatt, Feuerstein with a peak power of
120 kw. at 5,000 pulses and a smaller transmitter, Feuerhilfe
with a power of 30 kw. which had been improvised by Köthen.
These three powerful transmitters were used to pick up the Gee
transmissions and retransmit them but with a very slightly
different p.r.f. A keying arrangement was incorporated so that
the pulses of the master and slave stations could be imitated.
67. In the immediate neighbourhood of the site it was expected
that the pulse powers used would be so high that the Gee
presentation screen would be completely jammed. At greater
distances aircraft would receive on each frequency used three
or four false pictures broadcast by the Feuerzange and
Feuerstein. As they transmittal their spoof pictures on
p.r.f's which differed only slightly from that used by the
British stations, the effect produced was that the false
pictures wandered very slowly over the true pictures so that
it was difficult for an operator to tell which was the correct
set of blips.
68. At the beginning an insufficient number of sets was
available to carry out this spoofing on all the chains, but by
January 1945 the site was fully equipped. The Germans were
convinced that this system was successful because on 2nd March
1945 at 1230 p.m. a number of fighter bombers paid them a very
unwelcome, visit and completely destroyed the site.
69. Consideration given to the idea of jamming the link
between the Gee ground stations, was never carried out as it
was thought that we would certainly anticipated such measures
by providing a number of reserve links, possibly on centimetre
wavelengths, or oven co-axial cable links.
70. When Gee jamming was first properly undertaken towards the
end of 1942, a large number of monitoring stations placed
about 100 km. apart were erected around the occupied coast
form Brest to Norway. Each site had two Heinrich transmitting
units, one operational and one spare, and monitored all
possible wavelengths. Changes of phase were also reported so
that German aircraft flying with Gee equipment could be
notified by W/T.
71. The whole problem of Gee jamming was considerably
simplified on the few occasions that we made unexpected
frequency changes, because our transmitters lined up on the
new frequency before they were used operationally. Had this
not been done the effectiveness of the German jamming program,
might have been considerably reduced.

72. As has been mentioned in a previous report of this series,
the discovery of Loran came as a great shock to the Germans
because Professor von HANDEL had convinced himself that a
long-range, comparatively long-wave pulse system would be too
inaccurate for employment as a means of navigation. The
Germans' first knowledge of the system was obtained about the
middle of 1944 when maps were captured, and ultimately a
complete apparatus was obtained from an American aircraft.
73. Attempts were made to jam it, and by March 1945, 10 to 20
one kW noise jammers, which jammed the ground wave
satisfactorily within a radius of 50 to 100 km., were in
operation. At this time transmitters to meacon the pulses were
being built and consideration had been given to jamming the
synchronisation of the transmitters from the ground, using a
100 kW. C.W. transmitter which was to be erected as near the
front line as possible in order to be near the ground link.
74. The transmitter was ready and hat been taken to Thüringen
but the disruption of transport and communications prevented
it ever being used operationally.

75. The same equipment was used for jamming G.H., known to the
Germans as Diskus, as was used for jamming Gee.
76. A number of jamming villages (Stördörfer) with from two to
eight Heinrich transmitters were deployed throughout Germany.
It was calculated in December 1944 that at 20,000 feet G.H.
could only be received and used up to a line joining Emden and
Kassel and from there swinging South in an arc to Stuttgart,
while at 33,000 feet reception was thought to be possible up
to an arc joining the mouth of the Elbe, Weimar and Augsburg.
77. In addition, it was planned to use the powerful Feuerzange
and Feuerstein transmitters in an attempt to trigger-off the
ground stations from the Feldberg/Taunus Stördorf used to jam
the Gee chains.

78. In the autumn of 1942 a new type of radar signal in the
200 mc/s band was picked up by the German monitoring service
at Calais. Statistics were kept and it was observed that these
transmissions occurred mainly at night, and seemed to be
associated with British M.T.B. activity in the Channel.
79. In about June 1943 the same type of radar signals was
heard in Essen during a very heavy bomber raid on Cologne and
Dr. SCHOLZ was able to correlate them with the dropping of
T.I's visually observed. It was realised at once that these
signals were the same as those heard at Calais and an
immediate investigation was carried out. For this purpose a
"noise investigation commission" was formed and a special
experimental Freya with a number of D/F receivers was set up.
The Freya was used to plot the course of the T.I.-carrying
aircraft while the receivers D/F'd and monitored the signals.
80. Some 6 to 8 weeks after the signals had first been
attributed to path-finders, a satisfactory story had been
worked out by the Germans as to how Oboe, called by them
Bumerang, worked. When this had been accomplished, subsequent
Oboe raids were systematically monitored by the normal
monitoring service.
81. At this time (August 1943) plenty of jammers were
available because of the reserve apparatus available for use
against 200 mc/s radar stations on the Channel coast. Ten
sites were chosen to give jamming coverage over the Ruhr and
eight ½ KW MCW Karl jammers employed at each site. The
standard Mont Couple modulation also used against C.H.L.
stations was applied giving 150 mc/s sine wave modulation at
100 c.p.s from an unsmoothed H.T. line.
82. The radio frequency was determined by picking up the
aircraft return signal and tuning the jamming transmitter
until the normal signal failed. Four frequencies in the 200
mc/s band were ultimately detected, but though the ground
station frequencies were found to be steady, those of the
airborne transmitter were not very stable.
83. Aerials recovered from crashes appeared to be mounted
sometimes en the starboard wing and sometimes on the port wing
of the aircraft. This fact, combined with some information
obtained from a British P/W, caused the Germans to believe
that the aerials were directional, and in order to jam more
successfully, all transmitters were moved to the West of the
84. Jamming was almost entirely confined to the Ruhr area
because this territory was far away, the most important target
within the limited range of Oboe. The Germans were greatly
relieved when Oboe was used against the rocket sites in
Northern France, as the pressure on the industrial Ruhr was
thereby reduced. From about December 1943, intermittent
attempts were made to jam Oboe ground stations from the site
at Mont Couple behind Calais. These were not very successful -
a fact which was attributed to the beam width of British
85. In June 1944 a new form of jamming which was known as the
Ballverfahren was suggested. This was essentially meaconing,
using an A.B.G. responding transmitter in the hope of
confusing the aircraft's return signals to the ground station.
It was believed to work well, and P/W quoted as an example a
raid on Nürnberg when aircraft deviated from their course as
soon as the jamming was switched on and returned to their
course when it lifted.
86. An instance of the success of Oboe jamming on the Ball
system was quoted. In June 1944 an oil installation - possibly
Wanne-Eickel - was the target, and all Oboe aircraft were
successfully jammed. The T.I's were dropped late and some 8 km
away from the target. As a result of this the main bomber
force spread out and many aircraft were shot down.
87. Only one metric Oboe receiver fell into German hands and
that was 90% destroyed; although the Germans knew the
principle, therefore, the details of the airborne set were
lacking, and the effectiveness of jamming could only be judged
by the accuracy of bombing.
88. By observing on a Freya the point at which bombs left the
aircraft, the Germans estimated the accuracy of Oboe as 300 x
300 metres for bombing from 9,000 metres, but a further 200
metres of ballistic inaccuracy occurred, giving an effective
error of 500 x 500 metres in the Ruhr area.
89. The success of jamming Oboe was considered to depend
partly on the training of personnel, so it was less effective
on a new target than on an old target which had been jammed
before. It was finally believed that the jamming was 90%
90. The Germans claim to have been so familiar with Oboe that
they were able to plot aircraft and withhold their jamming
until the aircraft turned onto the bombing run. They were then
able to identify the real target and localise the air-raid
warnings so as to disturb industrial production in the
neighbourhood as little as possible.
91. It is of some interest that on several occasions there was
a consistently good concentration of bombs in an open field
near Leverkusen, which P/W presumed to be due to an error in
computing the exact location of the target.

92. Signals which were recognised as Oboe by the type of
coding were detected on a wavelength of 9 cm on the Channel
coast about the spring of 1944. The normal monitoring service
had previously intercepted unexplained 9 cm. signals in
October 1943 but had not finally connected them with Oboe.
93. When 9 cm. Oboe was recognised, it presented the Germans
with a great problem, as no jamming valves were available for
that frequency and German intelligence had not given any hint
that a centimetre version of Oboe might be produced.
94. By July 1944 a valve called LD.7o (= 7 ohne = without) had
been produced, which was an LD.7 valve without cooling fins. A
transmitter unit called Feuermolch, tuneable from 8.6 - 9.6
cm., pulse modulated and giving 3 kW peak pulse power, was
than built. The whole apparatus, a Feuermolch transmitter
together with a mirror reflector to achieve 200 km. range by
beaming, was called Feuerball or A.B.G. (Anti Bumerang Gerät).
95. Jamming on 9 cm. Oboe was first used in operations in
October 1944 at Weser and Leuna. The Feuerball jammer was used
as a pulse repeater, after the frequency had been established
by interrogating the aircraft. The jammer then set up ringing
between the aircraft and jammer on the Ball system used
against metric Oboe.
96. The latest type of centimetric meacon responder called
Feuerburg had receiver and transmitter aerial mechanically
linked to follow individual aircraft, the jammer aerial system
giving a beam of 13° width. The aircraft was followed by hand
by means of a spinning dipole in a receiving dish.
97. According to Dr. SCHOLZ the wavelength originally used by
British centimetric Oboe was 9.26 cm. Sites were set up with
both 200 mc/s and 9 cm. jammers so that either could be
selected by a change-over switch on the receivers.
98. The jamming of Oboe by spoof massages was never tried
although the meaconing jammers were fitted with a keying
arrangement which would have allowed them to attempt this.
99. Oberleutnant Dr. BÄHRE of Ln. Versuchs Regt. Köthen had
doubts as to the effectiveness of the Ball system and had
proposed building a jammer with a very high p.r.f. to saturate
the aircraft receiver with pulses so that the strength of each
individual pulse re-radiated by the aircraft transmitter would
be greatly reduced and the range of the system would therefore
be considerably decreased. The Roland J transmitter which had
been designed for H2S countermeasures was to be adapted by
Lorenz for this purpose, but the idea was never put into
operation as the end of hostilities occurred shortly after it
was made.
100. An example of the success of jamming centimetric Oboe was
quoted and concerned a series of five raids on Gotha. Three
attacks, each with between three and five aircraft, were
unjammed and all scored hits on the railway station. The
fourth attack was jammed and no hits were scored on the same
target. The fifth attack was again let pass without jamming
and the station was once more successfully hit.
101. A further proof of the efficiency of the Ball system was
that in plotting aircraft a diversion from track could be
induced when the jammer was switched on and the aircraft would
return to track if the jammer were switched off again.
102. On the only occasion on which a 9 cm. Oboe aircraft was
known to have been shot down, it crashed in the Zuider Zee in
shallow water where it could neither be reached from shore nor
by sizable ship, and it was not possible to salvage the
equipment. As a result, the Germans never obtained any Mark II
Oboe equipment and detailed information as to how the system
worked was always lacking. There was no explanation, for
instance, of why certain aircraft transmitted pulses which did
not appear to have normal Oboe coding, although the aircraft
flow at heights and along tracks which obviously identified
them with Oboe procedure.
103. No advance information of the target could be obtained
from these aircraft but this was easily obtained from the W/T
transmissions between ground stations. The W/T channel used
was also monitored in order to see if jamming had been
successful. It was also noticed that some aircraft would not
respond to the interrogator but the reasons for this were not
fully understood. These aircraft seemed to be operating on a
wavelength above 9.6 cm.
104. A new valve to cover the 9.6 - 10.6 cm. band was being
produced by Dr. GROOS. It was a 100-watt Klystron and it was
proposed to jam with its aid as soon as it was finally
105. Towards the end of the war there was a great increase in
the daylight use of Oboe but P/W did not believe that the
Americans had ever used it. With so many aircraft over Germany
towards the end of the war correlated evidence was not

106. Shortly after the discovery of H2S in January 1943 panic
orders were given for the production of a jammer. Later in the
year Roderich, which was manufactured by Siemens and which
used a Magnetron of theoretically 5-watt power, was made
available. The transmitters were unbeamed and the power was so
low that they were useless. By 1944 the use of Roderich had
been discontinued.
107. The difficulties of jamming highly-beamed centimetric
radar were so great that it was decided that all that could be
done was to attempt to defend a few vital targets. The first
target to be chosen was the Leuna works which was considered a
good target.
108. The Reichspost Zentrale was called on for assistance and
Dr. GROOS of that institution successfully developed a
Klystron valve, which was a water cooled 100-watt valve
tuneable by hand from 8.5 - 9.5 cm. This was built into the
jamming transmitter which was known as the Postklystron.
109. In order to concentrate as much of the energy as possible
to the aircraft, horns or paraboloid aerial reflectors were
employed with the transmitters. About eight sites around Leuna
were chosen, bearing in mind that the attacks always seemed to
use a route coming in from the North, presumably because the
best H2S pinpoints lay in this direction.
110. Four Postklystron transmitters were placed on suitable
sites and spaced in frequency across the observed 30 mc/s band
of H2S by putting them about 5 mc/s apart and making use of
the side bands from 2 - 10 mc/s single frequency amplitude
modulation. This barrage was used with low directivity.
111. A second type of jammer employed made use of the Roland
transmitter built by Siemens, which had a 30° beam, but its
development was abandoned about March 1945, as it was not
considered very successful.
112. In yet a third system Postklystrons were used with a
beamed aerial system giving a lobe 6° wide. The transmitter
was coupled mechanically to the D/F, receiving aerial of a
Korfu receiver, its aerial being provided with rotational
eccentric split. The receiving aerial was trained on a single
H2S bomber, which was followed manually.
113. The detection range for setting up was about 300 km. With
the less beamed type, Roland, effective jamming ranges up to
about 30 km had been obtained but with the narrow 6° beaming
the H2S tube was completely obliterated at 40 km if the beam
was focussed on the H2S aircraft.
114. One P/W had flown with H2S equipment installed in German
aircraft in order to carry out experiments in ground
camouflage against H2S with the aid of corner reflectors. The
conclusion was that corner reflectors were ineffective. It had
originally been planned to cover arms of the sea and lakes
with corner reflectors, but in the first place too many were
needed, and in the second place arrangements had to be made
for these to remain fixed in a certain orientation in order to
produce an effect.
115. Another suggestion had been made that metallic powder
could be used to increase the reflectivity of an area. This
was obviously no use as camouflage for a target, which was the
end originally in view. Consideration was given to producing a
dummy target with its aid but it was concluded that the
quantity of powder necessary was so enormous that it was not a
practical proposition.

116. The Germans had such leeway to make up with the production
of 3 cm valves that no active countermeasures against H2X had
been put in operation up to the end of the war. Development of
a transmitter called Roland 2 was started in December 1944
with Telefunken Ceramic 3 cm valves believed to be known by
the designation LD.72 and LD.77.
117. The set was to be modulated by 100 kc/s pulses and to
sweep through a small radio frequency band. The power achieved
was 50 watts average. With horn aerials a 20° beam was to be
achieved. The range against an H2X set which had been captured
undamaged at Wiesbaden was 20 km. in the initial experiments.

118. Owing to the strong beaming and method of sweep of
centimetre A.I. the G.A.F. was doubtful if any jamming would
be possible. No airborne transmitters against centimetric radar
were developed.


Acknowledgements are due to the various technical bodies,
both British and American, who collaborated in producing the
technical information contained in this report.
A.D.I.(K) and S.D.Felkin,
U.S. Air Interrogation. Group Captain.
29th August, 1945.

The A.B.G.(Anti Bumerang Gerät) meaconing jammer was first
used in June 1944 and was an idea fathered by P/W. It was a
responder beacon which was employed against Oboe to set up
"ringing" between the aircraft return signal and the A.B.G. so
that the aircraft return to the ground station was confused.
The jamming transmitter had a 20 - 30 kW power in the case of
the model used against 200 mc/s Oboe. In the A.B.G. used
against 9 cm. Oboe (Feuerball) the power was 3 kW.

This was the pulse modulated transmitter with a range from
20 - 250 mc/s developed and built in the G.A.F. laboratories
in PARIS. It was believed to have consisted of six or eight
½ kW transmitters. Some 50 sets only were put in hand and
about half of them were completed. It was thought that they
had been used against ground radar stations along the Channel
but with what success it was not known.

This was the name for the A.B.G. centimetric responder used to
jam centimetre Oboe. The jammer was used as a pulse repeater
and set up ringing between the aircraft and the jammer. It
consisted of a transmitter using a klystron valve developed by
the R.P.Z. which covered the frequencies 9.0 - 9.6 cm., backed
by a beaming reflector. The peak power was about 3 kW.

In order that the Feuerball transmitter should be beamed on to
the transmitting aircraft, a beamed receiver was mechanically
linked to the Feuerball set. The receiver was operated so that
the receiving mirror was aligned on the aircraft and the
Feuerball paraboloid mirror followed any changes of elevation
or direction made by the receiving operator. This complete
set-up of beamed Korfu receiver with a Feuerball beamed
transmitter was known as Feuerburg.

This was a smaller form of Feuerstein improvised by Köthen
with a peak pulse power of 30 kW.

This was a two-stage inductive transmitter (final stage
LS.1000) manufactured by Blaupunkt and served the same purpose
as the Karl II. The first production sets were ready in March
1945 and were believed to have been sent to the Holstein area,
but they were never used operationally.
The frequency of the Feuerland could be adjusted from
30 mc/s to 300 mc/s by means of interchangeable H.F. coils.
Different types of modulation could be introduced according to
whether it was to be used against R/T or radar. Against R/T it
was known to have had the four-tone chime modulation described
under Nervtöter below. It could also be used with noise
modulation with an adjustable bandwidth up to 2 mc/s. The
power output was about 350 - 500 watts.

This was the name given to the centimetric transmitting
equipment of the Feuerball.

The Feuerstein designed by Telefunken was used for producing
a false picture on Gee sets, the keying of the pulses being
carried out by equipment supplied by Telefunken and Siemens. A
number of these sets were installed on the Feldberg. It was a
high-power pulse transmitter at frequency range of either 20 -
52 mc/s (known as the Feuerstein 1) or 48 - 90 mc/s (known as
the Feuerstein la). At a p.r.f. of 5,000 cycles it had a peak
power of 120 kW.

This was the highest-powered pulse transmitter possessed by
the Germans and was used in 1945 on the Feldberg to provide
spoof Gee transmissions. The transmitter, developed by Dr.
FREUDENHAMMER and built by Siemens, was water-cooled and could
be modulated in exactly the same way as Feuerstein. The
frequency range of the transmitter was 20 - 87.5 mc/s and at a
p.r.f. of 5,000 cycles a power of 1 megawatt was claimed. It
was considered a very effective set but only came into
operation towards the end of 1944.

Garmisch Partenkirchen was believed to be an improvised
airborne apparatus, probably manufactured by Neufeld and
Kuhnke of Kiel. It was used to a very limited extent in 1941.
It consisted of a receiver which picked up a ground radar
transmission and re-transmitted on the same wavelength but
returned no less than five different pulses with slightly
different phases with the object of creating false echoes. As
these false echoes could be immediately identified if a second
ground radar D/F’d the jamming aircraft, the idea was carried
no further.

An experimental spark, ground jamming transmitter for
employment against flight radar and using a 1/2 wavelength
dipole aerial in front of a reflector, was given the code name
Gewitterziege. The band width was very large but it was
claimed that it was an effective jammer at close range.

This transmitter was developed by the Reichspost Zentrale in
1942 with the specific intention of providing the G.A.F. with
a jammer against the Gee navigation system. A large number of
these sets was built and deployed all over Germany to jam Gee.
A set of the same type, from which Heinrich had been
developed, was used in Sicily in July 1942 for jamming the
radar stations in the 50 - 80 mc/s band in Malta.
In its ultimate form, Heinrich II, the transmitter had a
power of 500 watts and covered the band from 20 - 90 mc/s in
four separate sections. For this output it used four LS.180
valves arranged in parallel push-pull.
It was 100% modulated by 150 kc/s sine wave with the
addition of 100 cycle ripple obtained from an unsmoothed H.T.
power supply. The set needed only two controls, one for the
main tuning and one for the aerial coupling.
The aerial consisted of a wide band dipole of squirrel cage
circular section, with normal tapping at the feeding point.
This one aerial was used in the entire frequency band from 20
– 90 mc/s. It was stated to have a standing wave ratio of 20%
in voltage.

This was the standard jamming transmitter for use against
British radar and was designed to cover the frequencies 90 -
250 mc/s in two bands. Development work on it was started at
the end of 1940. The transmitter employed four LS.180 valves
and had a power output of between 300 and 500 Watts. It was
modulated by the standard Mont Couple 150 kc modulation on
which a 100-cycle tone coming from an unsmoothed 50-cyle
source of supply was imposed. The type of modulation employed
could not be changed in the field.

This was on improvement of Karl I with few changes in the
electrical specifications but it was really composed of two
more powerful Karl I units with a common feed. It was also
modified so that any desired standard type of modulation could
be substituted at the site where it was employed, thus
obviating the necessity for returning the transmitter to the
factory, as was the case with Karl I.
The Karl II employed an LS.1500 valve with an output of
2 kW, and besides being used against ground radar, it had been
modified for use against R/T with the Post type of modulation.
It was not known what degree of success had been achieved with
this set.

The original Karuso I was improvised by the R.P.Z. with the
specific object of providing aircraft with an airborne
transmitter to jam the R/T link between the British ground
control stations and British night fighters. It was origina11y
intended to sweep through the whole 100 - 120 mc/s band. 0wing
to the relatively large frequency sweep, however, jamming was
not vary effective, so it was manufactured in two forms, to
sweep from 100 - 110 or from 110 - 120 mc/s.
It had ultimately an effective range of about 5 km. and a
power of about 30 Watts. Altogether, only 100 sets were
The designation Karuso II was given to a development which
never got farther than the laboratory stage, but Karuso III
was produced and covered the 100 - 150 mc band. The width of
the jamming band was only 3 mc/s and the frequencies used was
set up on the ground according to intelligence information
given by the German "Y"-service. It was not known whether this
set was used operationally.

Kettenhund was a 30 watt air-born jammer developed in 1943
by a certain KETTEL of Telefunken covering the 170 - 200 mc
band. It was used against British ground radar stations in
raids over South-West England in 1944. Tests with the set led
the Germans to the conclusion that it was not very effective.
Modulation employed was a triangular wave with a frequency of
several hundred kc/s.

This was the name commonly applied to a centimetre jamming
transmitter witch was also referred to as the "Postklystron".
It acquired this name because it made use of a centimetre
klystron valve developed by Dr. GROOS of the Reichspost. A
power of 100 watts was claimed for it. It was a CW jammer
which could be tuned by hand between 8.5 cm. and 9.5 cm. It
was fitted with a horn aerial to be aligned on the approaching
H2S force. It was claimed that at a range of about 40 km. the
H2S tube was completely obliterated when the Postklystron was
focussed on an individual aircraft. This set came into
operation about March 1945.

The Kobold was an airborne set designed by the Post
specifically to jam A.S.V. and was originally used in the
Mediterranean in conjunction with a Karl transmitter working
from the ground. It was, in effect, half a Karl transmitter
and used two LS.180 valves. A modulation of about 400 cycles
originating from the aircraft transformer was superimposed on
it. It had the handicap that it could only be built into very
large aircraft.

Nervtöter I was designed as an airborne transmitter to jam
Allied R/T but considerable difficulties were encountered in
tuning it in the air to the frequency observed and it was
never used in operations.
As a result of the criticism made by T.L.R., the Nervtöter
II, which was also believed to be known as FuGe. 40, was to be
developed. This set employed an LS.50 valve in the final stage
and the frequency of the R/T was to appear as a blip along is
time base on a cathode ray tube, while the frequency, to which
the transmitting jammer was adjusted, appeared on a similar
blip on a second time base on the tube. By setting these two
opposite each other the operator could easily see that he was
jamming the required frequency.
A so-called chime modulation of four changing tones was
used. The power output was 25-30 watts and the frequencies
ranged from 90-160 mc/s. Wide band aerials were to be used.
This set had not got beyond the experimental stage by the end
of the war.

Olga was a self-excited, grid-keyed, one valve transmitter
(LS.180) developed by the Navy and had a frequency range of
150 - 200 mc/s and an output of about 300 watts. It was
believed that a p.r.f. of 500, 700 or 900 cycles was used.
This jammer was an early type used against British coastal
watch radar without much success.

This was the name applied to the first set developed by
Siemens for jamming H2S when panic counter-measures were
called for early in 1943. It used a magnetron valve with a
maximum power output of 5 watts and was virtually of no use
whatsoever. It took some months to develop; in the meantime,
German knowledge of how to Jam H2S had increased to such an
extent that it was never used.

The Roland jammer was developed for use against H2S by Dr.
WEHRMANN of Siemens and was said to employ a triode
transmitter valve designated L.D.72 or possibly L.D.75. The
wavelength was 8.5 - 9.5 cm. and with the aid of a horn aerial
it produced a 30° beamed transmission, modulated, it was
believed, by 100 kc sine wave and pulses of an unknown p.r.f.
It had less than 50 watts average power. The range at which
obliteration of the H2S tube was claimed, was about 30 km.
The Roland II was the name applied to an attempt to produce
a similar set on 3 cm using, it was thought, a LD.77 triode
valve and a horn aerial a 20° beam. It is doubtful if it was
used operationally as the valves had a very short life.

This was believed to be the precursor of Kettenhund and was
designed by D.V.L. Adlershof in about 1940 but never used. In
a document there is an indication that attempts were later
made to use it as an R/T airborne jammer; A.D.I.(K) 231/1944
also gives an account of preparations to use the Starnberg

Wolke was believed to be the code name applied to the first
German attempt to imitate a noise jammer like that used by the
Allies. It was believed to use two L.D.5 valves in the final
stage and to have a carrier frequency of 90 mc/s. The average
power output was 15 - 20 watts, the width of the noise band
being about 2 mc/s.
As a result of the examination of Wolke the conclusion was
reached that noise modulation required too many valves and too
much power and that with the some number of valves a better
effect could be obtained with other types of modulation. The
set was therefore used for training night fighter crews to see
through electronic jamming of SN.2."
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SECRET A.D.I.(K) Report No.320/1944

1. The information contained in this report was obtained from
selected P/W of the 8th Kompanie of Ln. Regiment 53, who were
captured on 17th June 1944 at a Radar station which they were
manning 2 km. to the East of Douvres. The site consisted of
two Würzburg Riese and two Freyas without the A.N. attachment;
one of these Freyas was of the mobile type, and was not
operational pending its being changed for one of the fixed
2. The operators as a whole were not particularly
knowledgeable, but were able to give some interesting
information on the way in which Allied air attacks affected
operational efficiency of the station. One member of the
station, an officer, was more knowledgeable than the others
and added some odd scraps of information on other Radar
equipment, which are summarised in this report.

3. The beginning of May saw the opening of almost daily air
attacks on the Radar station at Douvres; from this time until
D-Day the site was subjected to bombing, machine-gun and
rocket projectile attack from Thunderbolts, Typhoons and
4. Surprisingly little resulted from those attacks; eight men
had been killed and one barrack building had been burnt out,
but the Radar installations themselves, protected as they were
by heavy brick work, were practically undamaged. Apart from
short intervals of a few hours for repairing cables and
aerials severed by M.G. fire, the installations were,
according to P/W, continuously in operation.
5. It was stated R.P. attack was particularly ineffective,
but that machine gun fire into the cabins of Radar
installations was both feared and effective. During air
attacks, therefore most of the personnel of the station,
including crews from the Würzburg and Freya cabins, went to
the "Bunker" shelters.
6. On the night of 6th/7th June, the Kompanie had been busily
employed in plotting Allied shipping and at 0100 hours on that
night the Würzburg had plotted same 100 ships, which
information was passed through to Jafü 5. At 0300 hours a
large number of bombs fell in the neighbourhood and all the
personnel left their posts to take to the shelters, leaving
the apparatus unattended.
7. From D-Day onwards the Würzburgs and Freyas were kept
operating even with the added weight of artillery and tank
attack and the equipment was, in fact, operational until a few
hours before the site fell to the Invasion Forces. It is,
therefore, clear that in an operational sense the site
survived nearly five weeks of constant attack.
8. When capture became imminent, however, all technical
apparatus on the site was destroyed by explosive charges. The
personnel put up a good defence, and it was not until the
Allied tanks broke through the protective minefield that the
station finally surrendered.

9. The plotting room on this site, which correlated data
received from the Freya and Würzburg, was housed on the top
floor of a two-storey "Bunker" - a box like building partly
sunk in the ground and constructed of concrete two metres
thick. It had originally been intended that, in addition to
handling normal Würzburg and Freya searches, the plotting room
should also be employed for control of night fighters, but
since there were no night fighters operating in this area, this
latter function had never emerged; in any case the Seeburg
Tisch had not been installed, although provision for it had
already been made.
10. At the time of the Invasion, the plotting equipment
consisted of a ground-glass screen, measuring some 8 x 12 ft.
let into a wall, the glass bearing a map on which the plots
were drawn. In addition to this a small-scale map of Northern
France, overlaid with tracing paper, was laid flat on a table
but this latter had never been put into use, having been
forestalled by the Invasion.
11. In operation, plots from the Würzburgs and Freya were made
in pencil, no distinction being made on the ground-glass
screen between friendly and enemy plots.
12. The plotters, who wore earphones, received their
information direct from the operators of the Freya or
Würzburg, and transferred their plots to the ground-glass
screen. A man called an "Ableser" then read off the plot from
the ground-glass screen and telephoned it to Jafü 5 at Bernay,
and latterly in the Western suburbs of Paris.
13. At one end of the room there was a platform on which sat a
supervisor, who was responsible for the accuracy of the
plotted information. He kept his eye on all plotting whilst
listening to information as it came from the Radar equipment.
He had a small telephone at his side through which he could
plug in to any line from Würzburg or Freya.

General Remarks.
14. The only knowledgeable P/W, an officer, gave as his
opinion that British and American Radar technique are slightly
ahead of their German counterpart. In German Signals circles,
he said, it is openly admitted that any piece of Allied radar
equipment is seized upon and studiously copied.
15. One major difference, he believed, was that Allied Radar
equipment was always smaller and more compact in construction
than similar German apparatus.
Hand written comment: but the German Rotterdam weighs about
half H2S - its British original!
16. Some few details on current German Radar Geräte were given
by the above source. These are summarised below.
17. The Würzburg Riese on the station at Douvres were of the
usual type, and had a search range of 30/40 kilometres.
The frequency of both Würzburg Riese was stated by P/W to be
600 mc/s.
18. Some operators of the Würzburg and Freyas, although
agreeing that they experienced interference from "window",
interference which showed itself in a series of specks and
lines on the presentation screen, maintain that because
"window" travels more slowly than an aircraft, an experienced
operator can distinguish the flight of the aircraft against
the tracks of the "window".
19. The officer P/W, however, is sceptical about all anti—
window devices, and believes that the German Radar authorities
are seriously perturbed by it.
20. Some few weeks ago Goering, it is alleged, offered a cash
prize of 300,000 Reichmarks to any Signals personnel who could
invent an apparatus to outwit "window".
Nürnberg Gerät.
21. According to P/W, the Nürnberg Gerät is fitted to Würzburg
in order to eliminate the effects of "window". This apparatus
has not been entirely successful, although it makes the
operator's job slightly easier.
"Würzburg Laus".
22. The "Würzburg Laus" is said to be an apparatus replacing
the Nürnberg Gerät as a counter measure for "window". The
apparatus in contained in a box 18 x 9 x 9 inches, which is
attached to the Würzburg.
23. The "Laus" is a much more recent development, and is said
to be somewhat more successful than the Nürnberg Gerät.
24. This is the colloquial name given to highly characteristic
interference pattern on the screen of the Würzburg and Freya.
The word is apparently associated with the barbed wire
entanglements of Flanders in the last war, and this gives some
indication of the picture which the interference makes.
25. P/W believed that this interference is a transmission
apparently on the frequency on which Würzburg and Freya are
operating, and same P/W have the idea that it emanates from
the Isle of Wight vicinity.
Köthen Gerät.
26. The "Köthen Gerät" is, according to P/W, not an apparatus
but a frequency of the Freya. For example, particular
frequencies on Freya are designated A, B, C and D, and Köthen
is merely another frequency deriving its name from an
experimental station at Köthen.
27. The A, B, C and D frequencies, P/W thinks, were produced
by civil firms, and the Köthen name implies that this
frequency is a development of the Luftwaffe's own experimental
station at Köthen.

28. Amongst documents found at the Radar station at Douvres
was a paper headed "Limbach"; this piece of apparatus was
stated to be attached to the V.H.F. transmitter/receiver in
the aircraft and to operate in conjunction with the Freya on
the ground.
29. The paper stated that the procedure employed with this
apparatus was similar to that of the Gemse - Erstlings
procedure, but strangely enough was used in conjunction with
the FuGe 7.
30. According to this P/W, the Limbach was superseded by the
Gemse - Erstling (FuGe.25).
31. The document in question has been forwarded to A.D.I.(Sc).

Rammstoss Gerät.
32. This is stated to be an instrument carried in German
bombers, its purpose being to show the position of other
aircraft and prevent collisions in tight formation.
Rotterdam Gerät and Panorama Gerät.
33. It is stated that both these instruments, Allied in
origin, are now being used by G.A.F. aircraft, but all P/W had
heard was that the Panorama Gerät had a wide focus, whilst the
Rotterdam Gerät was designed to show a small area.

34. At long last, after a lapse of 21/2 years, confirmation of
"Diana" has come to light through documents. The first
mention was from a notebook of a P/W of I/K.G.30 in August
1941 (A.D.I.(K) 420/1941), which stated that Diana was to be
similar in principle to Elektra, but working on a short-wave
band and within a frequency range of 3,000/6,000 kc/s.
35. The present document notes that "Diana" is similar to
Elektra but operates on short waves. This P/W stated that
"Diana" had not been operational.

36. The 53rd Ln. Regiment, to which the 8th Kompanie at
Douvres belonged, consists of a number of Kompanien ranging
from 1 to 26; The Kompanien are not necessarily numbered
consecutively, so that the total in the 53rd Ln. Regiment may
therefore be less than 26. All the Kompanien had code names.
37. The 53rd Ln. Regiment was responsible for an area bounded
on one side by the coast, and on the other sides by a line
running from the tip of the Cherbourg peninsula to the South
of Paris and northwards to Dieppe. Its Kompanien lie all along
the coast and towards the interior at a distance of 30/40 km.
apart; each Kompanie's area overlaps so that the entire
territory is completely covered.
38. The H.Q. of the 53rd Regiment is in Paris and is under the
command of Oberstleutnant FLECH, with Major HOFFMANN as

25th Kompanie.
39. The 25th Kompanie is the H.Q. Kompanie and has a strength
of 20/25 men, who were engaged in visiting Freya and Würzburg
sites of the Regiment and doing minor repairs. It was stated
that these men were by no means skilled engineers, and knew
nothing of the internal workings of the Freyas and Würzburgs.
8th Kompanie.
40. The 8th Kompanie at Douvres had a total strength of 160
men, who were divided as follows:-
Kompanie Stab............ Administrative Staff.
Zug 1 )
Zug 2 ) ................. Personnel manning the Freya
and Würzburg on six-hour
shifts day and night.
Flak Zug................. Personnel manning and
guarding Flak position
round the Kompanie’s site.
41. Another Kompanie of this Regiment, the number of which was
unknown to these present P/W, was said to be manning a site at
St. Valery-en-Caux.

42. Generally speaking, the morale of the 8th Kompanie during
the pre-Invasion raids was high, and their resistance during
the final attack on the station was certainly not suggestive
of low morale. It is noteworthy, however, that since capture
and the absence of the excitement of action, these P/W are
heartily glad to be out of the war. The majority are convinced
that Germany has already lost the war.

A.D.I.(K). S.D. Felkin,
30 June 1944 Wing Commander

1. The Deputy Commander of the 8th Kompanie at Douvres
an Oberleutnant - was good enough to bring his paybook with
him, and his career is therefore set out below as a matter of
Oct. 1937 – March 1938... Was with Ln. Abteilung R.L.M.,
2nd. Komp. at Potsdam (This was,
supposed to be one of the very
elite schools for Signals in
Germany before the war).
March 1938 – April 1938.. Was with Ln. Abt. R.L.M. 2nd. Komp.
in Vienna, and took part in the
April 1938 - Aug. 1938... Back to the R.L.M. 2nd. Komp. at
Aug. 1938 - Sept. 1939... Acted as Funker to Ln. Regt. 4,
7th Komp. in Vienna.
Sept. 1939 - Feb. 1940... Became a Horchfunker with Ln. Regt.
4, 7th Komp. At Cracow.
Feb. 1940 - March 1940... Was posted to the Ln. Officers'
Training School at Halle.
April 1940 - Aug. 1940... Joined Ln. Regt. 4, Abt. III as
Staff Officer. Here he was
in command of a Hörstelle.
Aug. 1940 - April 1941... Became O.C. of Horchstelle (W.24)
at Breslau. (P/W explained that all
these Hörstellen are described in
passon and paybook as Wetter
Funkempfangstelle which is in fact
only a cover name for Horchdienst).
April 1941 – March 1942.. Was at the depot of Horchstelle (W.3) which is at Athens. Here his job was to listen in to English ground telegraphic messages which were coded and decoded.
March 1942 - April 1942.. Posted to Nikolaiew in Russia as Staff Officer to III Abteilung Ln. Regt. 4.
April 1942 - May 1943.... Served in Ln. Regt. 130, who were
there in the South Russian sector in support of a Flak division.
May 1943 - May 1944...... Became O.C. of the 11th Komp. Of
Ln. Regt. 57 and later O.C. of the 7th Komp. Of the same Regiment then
near Orleans.
2. In May 1944 he was posted to his present unit (Ln.53, 8th
Komp.) as Second-in-Command to Hauptman EGLE. He says that it
was intended that he should take over this Company in a very
few weeks' time.
Erinnerungsmedaille for Austria.
Erinnerungsmedaille for Sudetenland.
K.V.K. Second Class with Swords.
Rumanian Cross given to those who fought against
Krimm Shield, which commemorates the battles of
the Crimea, including Sebastopol and Kersch and
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SECRET A. D. I. (K) Report No. 318/1944

1. Attached is a translation of a paper issued by the General
der Flakwaffe on 24th May 1944 concerning the British 'Oboe'
procedure - called by the Germans the Boomerang.
2. Apart from showing that the enemy understands the working
of 'Oboe' the report is of interest as it indicates the lines
on which German defence was concentrating. Night-fighters are
dismissed summarily and the main hope is that, by knowing the
approach course, the height and the speed of the attacking
aircraft, the Flak defences must be concentrated near the bomb
release point so as to produce a "Vernichtungsfeuer" by which
success was certain. The report also hints that, since the
German knew the 'Oboe' frequencies, radio counter-measures
were in hand.
3. One other point of interest is the high standard of the
plots of aircraft attacking on the night of 2nd February 1944.
This Sketch of is reproduced as Appendix II.
4. The original document has been passed to A.D.I.(Science).
29 June 44. Wing Commander

Oberkommando der Luftwaffe Bernau b/Berlin d.24.5.1944
Tel.: Berlin 56 40 76 App.:122
General der Flakwaffe Bernau 814 u.815 od.üb.
(General der Flakausbildung) L.V. 12.
Az. 79 m Nr.0236/44 g.Kdos.(A/C)
Number of Copies: 250.
Copy N°: 79.
Subject: Combating "Boomerang" Aircraft.
Attached are instructions for dealing with aircraft attacks using the Boomerang procedure.
In view of the importance of defence against this new method of attack adopted by the enemy it is imperative that all units be instructed in the Boomerang procedure and that counter—measures are adopted on the lines laid down in the attached instruction.
Subsequent observations and experiences are to be reported to the General in charge of A.A. defences.
All independent Flak Groups as well as interested sections of
O.K.L., O.K.H., O.K.M., SS-Führungs-Hpt.-Amt, Höhere Kdre.,
Flakersatzdivision General der Jagdflieger,
Generalnachrichtenführer, General d. Kampfflieger u.
GL/Flaktechnisches Amt.
(Sgd) v. Axthelm.

Encl. To: OKL – Gen.d.Flakwaffe
Nr.0236/44 g.Kos. (A/C)
Dated 24/May/44.
A. General.
Recently, nuisance raids have been developing more and
more into high altitude precision attacks against pin-pointed
targets (particularly important industrial complexes) by means
of a special navigational procedure known as the "Boomerang"
procedure. So far, "Boomerang" attacks have only taken place
at night on the Rhine-Westphalian industrial area, Aachen and
Osnabrück, airfields and railway stations, in the area of
Luftgau Belgium/N. France, Paris and targets in Brittany.
The "Boomerang" aircraft employed were Mosquitoes belong
to 105 and 109 (B) squadrons, stationed at Marham. Immediately
after take-off the aircraft climb to the prescribed attacking
height of 8,000 to 11,000 metres, with a view to checking wind
The enemy is carrying out on an increasing scale his precision attacks and pathfinder technique using the "Boomerang" procedure. It is clear from the increase of activity that the enemy is constantly expanding his
"Boomerang" organisation and improving the technique. An expansion of these attacks on further targets with ever increasing effect is the result.
It is therefore essential to bring to bear everything in our power with a view to combating "Boomerang" aircraft. The basic principle is that aircraft must be shot down.
B. The "Boomerang" procedure.
The "Boomerang" procedure is the most accurate method of remote control at present known. It consists of controlling aircraft by means of Radar stations located in S., S.E. and E. England. These stations work together in pairs of which one is the main station, and passes navigational signals to the aircraft. One signal from this station indicates the course to
the pilot whilst the other is for the bomb-aimer to release the bombs. (see App. 1).
The aircraft to be controlled flies under its own control to an agreed point, where the remote control takes over. The aircraft is then directed by W/T to the turning point, which is on an arc centred on the Radar station in England and passing through the bomb dropping point. Constant corrections from the ground station in England keep the aircraft on its
course (see App. 1) but in spite of the great accuracy of measurement deviations up to 300 metres are possible.
The total time required for the target approach is 8 to 15 minutes. As soon as an aircraft passes over the target, the next one is taken over by control. The time interval between attacking aircraft is frequently reduced by attaching several uncontrolled aircraft to one controlled aircraft, or by using further pairs of Radar stations. The uncontrolled aircraft aim their bombes on ground or air markers. The approach to targets East of England is made from a N. - S., S. - N. or S. – W. direction. Targets South of England are approached W. - E. or E. - W. The course depends upon the relationship of the two Radar stations to one another. Unless there in a disturbance by a jamming station the final phase of the line of approach becomes an arc centred on the ground control station in England and passing through the objective to be attacked.
It has been observed that simultaneous flights to
different objectives on a N.- S., S.- N. as well as S.- W. and N.- E. courses, have been carried out, which proves that the enemy has already set up several ground stations.
The range of this system is limited by the curvature of the earth and for a flight at a height of 9,000 metres, the range is between 400 – 450 km. The bombing accuracy depends on the reading and measuring accuracy of the ground station in England. The accuracy is within a square of approximately .5 km. by .5 km.
So far, the followings types of "Boomerang" attacks have
been made:-
a) Single "Boomerang" aircraft.
b) One "Boomerang" aircraft followed by 2-5
uncontrolled aircraft.
c) "Boomerang" aircraft as Pathfinders for a
following bomber force.
d) "Boomerang" Pathfinders as decoy marker flaredroppers
and "window" aircraft. (Translator's note:
the German text is ambiguous. The word is
"Scheinmarkierer" which may mean decoy or
illuminating markers. The subsequent context
suggests the former).
The "Boomerang" Pathfinders at first saturate the approach and target area with "Window", then place light markers over the target. The bomber stream then follows up immediately on the "Boomerang" course.
C. Counter-measures.
The following take part in "anti-Boomerang" attacks:
a) Night fighters.
b) Radio jamming service
c) Flak.
I. Our own Mosquito night-fighters (sic) have not had any worth-while successes in shooting aircraft down prior to the bomb release or to the commencement of the Pathfinder activity.
Over a period of time, however, night-fighters should be more successful, provided high flying aircraft are employed. Uncontrolled night-fighting with the aid of search lights is possible if our own fighters are high enough and in sufficient numbers in the waiting area over the Flak zone.
Because of vapour trails, it is possible to pick out highflying aircraft by searchlights.
II. The radio jamming service has appreciated the principles
of the "Boomerang" system and has set up jamming stations. It
is possible to force part of the approaching aircraft off the
approach line by jamming. However, the enemy soon recognises
the disturbance and can change over to a pre-arranged
alternative frequency. The radio jamming service has already
met with success, but is still limited in its effectiveness.
III. The main burden of defence, now as before, rests with the
Flack. For the successful execution of the "Boomerang" system
conditions must be fulfilled:-
1. The attack must take place at a constant height of
about 8,000 - 11,000 metres.
2. The target approach must follow a fixed course for
several minutes. (Course for every objective known).
3. The ground speed must remain constant throughout the
approach. (140 - 180 metres/s.)
These known and partly constant target factors constitute
a great weakness to the enemy. In addition the Mosquito,
because of its wooden construction, is highly vulnerable to
well-directed Flak.
If, in spite of these favourable conditions, the Flak has only so far obtained little success, the fault lies in the increased factor of error when engaging targets at great heights, and also to the high speed of the Mosquito.
On the other hand, the courses flown at the moment are well-known. This factor, together with the known target heights and target speed, enable the point of bomb release for each individual objective to be calculated accurately and in advance. These known facts, combined with the total fire-poor of all batteries within reach of the bomb-releasing area, should produce a successful "Vernichtungsfeuer" (annihilation fire) and prevent accurate bombing and lead to aircraft being shot down.
D. Methods of Shooting.
1.) The shooting method employed on principal is annihilation fire.
2.) Provided that:
a) The course is known,
b) The target approach is fixed and confirmed by the
Malsi Flak Calculating instrument.
c) It is known with certainty that our own radio jamming does not result in the deviation of the enemy aircraft from its course and that the speed
and height remain constant. This contradicts L.Dv.400/4b und VER-Flak 18 Ziff.11)
3.) If the precise plotting is difficult, the following measures are to be taken:
a) The track is to be set in accordance with the known value.
b) The ground speed is to be obtained and passed on by the Flak transmitter. In the absence of this data, action is to be taken on the basis of previous experience. (Translator's note: in other words, use your own brains).
c) Height is to be obtained from accurately adjusted Radar and is to be passed over the Flak transmitter.
4.) With reference to the manner, in which "Boomerang" coursers are to be obtained for individual objectives, Commands will contact Luftgaukommando VI with a view to ascertaining the courses for their own
particular area.
E. Tactical Employment.
Suitable steps must be taken in the event of a change in the direction of approach of "Boomerang" aircraft, and if possible one to two batteries (special Eis. batteries) will be brought into the probable direction of approach for immediate action.
F. Counter-measures.
The following is to be noted when combating "Boomerang" aircraft:
1.) Most accurate alignment of the respective batteries (adjustment of instruments and guns, calibration of direction-finding apparatus, re-checking of ballistic correction of the moment in order to eliminate the
meteorological factor).
2.) Blocking together of the movement of target values:
a) Set course for known value.
b) Determine ground speed and height from previously emplaced batteries over Flak transmitter.
3.) As far as possible the Trupp should be provided with uniform ammunition (as few different batches as possible); calibration shoots should be carried out with this ammunition and muzzle velocity
determinations with (?special) calibration ammunition should be avoided.
4.) Accurate meteorological reports must be obtained every two hours for heights up to 11,000 metres. These must be actual and not extrapolated. Contact must be made with the nearest airfield.
5.) Charge temperature should is periodically determined by means the two specially equipped cartridges (Messcartuschen) placed in the ammunition dump.
6.) The ammunition used for checking drill time should be carefully controlled and the error should be eliminated.
7.) Preliminary practices should be made along the known lines of approach by means of special fire control tables prepared for this purpose. Test shoots should be carried out using intervals of one second. (FAS I
will supply fire control tables for "Boomerang").
8.) All actual "Boomerang" courses should be charted on the Malsi plotting table as a check against the actual plots. (See Appendix II).
A systematic research of shooting at great heights, having due regard to the available ammunition has been inaugurated. Results are to be expected shortly and until then all existing orders and instructions
hold good. In order to keep counter measures apace with the enemy's intentions, it is essential to inform higher quarters of any new observations made during "Boomerang" attacks. The Luftgaukommando and Divisions are instructed to report regularly their experiences of "Boomerang" counter-measures to the General der Flakwaffe.

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Northern Convoy Routes

SECRET A. D. I. (K) Report No. 410/1945

Norway and the Northern Convoy Routes.

1. In this series dealing with various aspects of the G.A.F. Signals Intelligence service in the war, it had been intended to conclude with the eighth report. Since the issue of the first report, however, another P/W has become available who had a comprehensive knowledge of signals activities in the Norwegian area throughout the war. It has therefore been found possible to add the present report, the ninth and final in the series.
2. The gradual expansion of signals intelligence based in Norway, and the Allied activities which it covered, are followed in this account from year to year from the time of the invasion of Norway onwards. In order that ready comparisons of the extent of that expansion may be made each year is dealt with separately, and maps showing the situation at various intervals during the war are appended.

3. Soon after the invasion of Norway in May 1940, signals intelligence personnel from W-22 at Husum were formed into a new unit and sent to operate at Oslo. This new unit was named W—Leit 5 and, subordinated to the Höherer Nafü of Luftflotte 5, formed the nucleus of the projected signals intelligence service in Norway; its initial strength was that of a Trupp, but by the autumn was to be increased to a Zug (platoon).
4. The function of W—Leit 5 was to act as the central organisation in Norway for the comprehensive monitoring and evaluation of all enemy R/T and W/T traffic in the North Sea area, and the watching of R.A.F. Coastal Command operations against the West coast of Norway. Information was to be passed to the higher signals intelligence authorities in Germany, who in return fed WLeit 5 with such data on Bomber Command radio traffic as was of value to the Norwegian area. The unit did not itself undertake
interception work, but confined its activity to organising the various intercept units and evaluating their results.
5. The first intercept unit, W-25, was set up at Trondheim, Skatval at the end of May with the strength of a Trupp, and also operated a H/F Adcock D/F set on Örlandet. This unit covered W/T traffic of 18 Group Coastal Command and W/T and R/T traffic from aircraft carriers, its intercept results being passed to W-Leit 5 at Oslo.
6. At the same time, W-25 was to make a local evaluation of its intercepted signals and pass the results to a specially appointed signals intelligence officer attached to Fliegerkorps X, so that the latter could amplify its air situation picture. Actually the greater part of the material passed by W-25 to the Fliegerkorps consisted of intercepts from reconnaissance aircraft of 18 Group.
7. At the end of August, W-25 was moved from Skatval to Stavanger, partly owing to the concentration of 18 Group's attention to that part of Norway and partly in order to be near Fliegerkorps X headquarters, which had meanwhile moved to Stavanger.
8. At the beginning of July another intercept Kompanie, 9/Ln. Regt. 2, had moved into Norway and had been put into operation at Naerland, near Stavanger. This unit employed an Adcock D/F station, whilst rhomboid intercept installations were planned and partly constructed during the latter part of the summer.
9. 9/Ln. Regt. 2 was to intercept the W/T traffic of 15 and 18 Groups and the H.F. R/T traffic of the fighters operating in the North of the U.K.; parallel with W-25 at Stavanger, this unit was to pass its intercept results to W-Leit 5 at Oslo and at the same time to make a local evaluation for the benefit of Fliegerkorps X.
10. In October the Signals Intelligence service in Norway began to take shape with the formation of an Abteilung, III/Ln. Regt. 5, subordinated to the Höhere Nafü of Luftflotte 5 both operationally and in its organisation. In December, 9/Ln. Regt. 2 at Naerland was renamed 9/Ln. Regt. 5.
11. The listening chain was completed by the subordination of W-22 at Husum (Schleswig Holstein) to III/Ln. Regt. 5. The duties of W-22 were essentially the same as those of W-25 and 9/Ln. Regt. 5, namely to feed W-Leit 5 with the results of its observations.
12. Owing to the lack of adequate D/F equipment in Norway at this time, and in order to ensure a full cover of Coastal Command operations, Husum also had to monitor 15 and 18 Group traffic. In addition, it shared with 9/Ln. Regt. 5 the task of covering the schools and ground networks of Coastal Command.
13. Once the full interception equipment of 9/Ln. Regt. 5 had come into operation at Naerland, W-Leit 5 was able to fulfil its primary tasks of controlling the coverage of the intercept station, evaluating the intercept results collected from the outstations by teleprinter tie-lines and distributing the resulting intelligence to all interested commands and units.
14. A situation report compiled from current messages and documents was produced each day, and every fourteen days a consolidated report was issued containing the more long term intelligence on strength and locations of enemy units, types of aircraft and tactics, and the identities of units being employed on specific operations.
15. Thus, from the late summer of 1940 onwards, intercepts of great value to G.A.F. reconnaissance units were regularly passed to the Operations Staff of Luftflotte 5. All important intelligence was immediately sent to Abteilung I of O.K.L.

16. Observation of 15 Group radio traffic was essential for providing the G.A.F. reconnaissance and coastal units with a picture of the air situation in that Group's sphere of operations. The watch on 18 Group by W-25 and 9/Ln. Regt 5 aimed at keeping a check on its strength and dispositions.
17. The H.F. R/T traffic of R.A.F. fighters based in the northern U.K. produced intelligence on defence tactics, organisation, strength and dispositions. This particular listening activity was supplemented by the D-Funker (interpreter radio operators), carried in aircraft of the long-range reconnaissance units for the purpose of evading attack by Allied fighters. When in April 1941, R.A.F. fighters converted to V.H.F. this practice was discontinued. In the late autumn of 1940 the 0.T.U.'s in Scotland and the Midlands were also covered.
18. Beacons in Scotland and the Midlands were covered by 9/Ln. Regt. 5 at Naerland from 1940 until the end of 1943. This work was controlled partly by W-10 (later the Leitstelle der Funkaufklärung) in Germany and partly by the Höherer Nafü of Luftflotte 5 for the benefit of G.A.F. units operating from Norway. The Kompanie supplied such information as it had collected on location, recognition signals, signals strength and method of
operation of the beacons, and was frequently called upon by Luftflotte 5 to suggest uses to which such beacons could be put for the benefit of the G.A.F.
19. Meteorological traffic was also covered by 9/Ln. Regt. 5, and intercepted messages were passed to the interested G.A.F. Met. stations in the Norwegian theatre and to W-22 at Husum for further distribution amongst stations in Germany.
20. Responsibility for breaking the Syko messages of Coastal Command reconnaissance aircraft lay with W-22 at Husum, and for this purpose traffic of 16 and 19 Groups and other networks were also intercepted in order to increase cryptographic depth. This traffic could not be broken with sufficient speed to be of tactical value, but it provided long-term intelligence on types, squadrons, dispositions, operational methods, distress signals and accidents. Results were forwarded in collated form to interested units on day plus one.
21. In the succeeding years W-22 was called upon to an increasing extent to cover various R.A.F. and U.S.A.A.F. formations. The breaking of other types of codes and cyphers was undertaken centrally by W-10.

22. In April 1941 R.A.F. fighter units in the North of England discontinued the use of H.F. R/T and converted to V.H.F., thus robbing German signals intelligence of a fruitful source of intelligence. From early summer, therefore, arrangements were made to experiment on the West coast of Norway with V.H.F. receivers and various types of aerial arrays; in the autumn V.H.F. experimental flights were carried out in the direction of the East Coast of Scotland with an aircraft specially provided by O.K.L.,
but results were disappointing.
23. By the summer, intercept equipment in use in Norway comprised 1 L.F. and 3 H.F. Adcocks as well as 5 interceptrhomboid installations. The function of the latter was to D/F ground transmissions with low signal strength, as well as the traffic of 15 or 18 Group aircraft operating at extreme ranges from the intercept stations.
24. The three H.F. Adcock stations were employed respectively for 15 Group, 18 Group and other radio traffic from unknown ground stations; the L.F. Adcock covered Coastal Command reconnaissance traffic, beacons and all other traffic from unknown ground stations.
25. In the autumn another radio interception Trupp, Wo-Hammerfest, commenced operations. This unit was to test reception conditions in northern latitudes for the purpose of covering bases in Iceland and the traffic of Allied long-range reconnaissance aircraft. The unit met with many difficulties, amongst which were the extreme remoteness of the unit and
consequently poor communications and 1ack of D/F equipment.
Reception conditions proved unreliable on account of atmospherics.
By the end of 1941 no solid results had been achieved.
26. In the meantime the organisation of signal intelligence in Norway was being developed. A signals intelligence officer was attached to the operations staff of Luftflotte 5; by the end of the year all signals intelligence units in Norway were subordinated to the Höherer Nafü Luftflotte 5, and all came under the administrative command of Ln. Regt. 5.
27. During this year the channels of communication of W-Leit 5 at Oslo were improved and at the close of the year comprised teleprinter lines to Berlin, Husum, Naerland, the G.A.F. exchange at Oslo and between Naerland and Husum. Direct telephone lines were also installed to Luftgau Norway and the Naval Command at Oslo.

28. The most notable development in signals intelligence in Norway during 1942 was the establishment in the summer and the preliminary organisation of a chain of intercept stations, known as D/F Base Atlantic, for the covering of Atlantic signals traffic. This chain was to comprise stations at Bodö, Örlandet, Naerland, Husum (Germany) and Brest, with Naerland as the central point.
29. The D/F Base Atlantic did not begin operations as an entity until the early summer of 1943, but its main functions were to supply an increased number of plots on 15 Group aircraft on convoy escort, end to watch the anti U-boat flying boats.

30. The experiments in V.H.F. interception begun during 1941 were continued but with little success. Various types of antennae were tried at different locations, and the special aircraft continued spasmodic flights towards the East Coast of Scotland, mainly to test antennae and to check up on new kinds of transmissions.

31. During the autumn it was decided that the interception Trupp, Wo-Hammerfest, was serving no useful purpose.

32. The interception Trupp established at Hammerfest during 1941 had supplied useful data on reception conditions in Northern Norway, but as far as operational results were concerned, no useful purpose was being served and the unit was withdrawn. Shortly afterwards, however, another similar unit began to operate at Svanvik.

33. Conditions for operation at Svanvik were found to be more favourable than at Hammerfest, besides which, the former station was provided with a D/F Adcock, and during the autumn the Trupp was busy with traffic from the two Allied convoys, P.Q.18 and 19.
34. From this traffic two main facts were elicited. The first was that some of the flying boats had transferred from Sollum Voe to Murmansk, whence they were flying anti U-Boat patrols. The second new fact was that the R/T traffic from land-based or escort carrier fighters could be intercepted and D/F'd.; in this way additional data to those from normal reconnaissance sources could be supplied to supplement the air situation picture.
35. Signals intelligence was particularly valuable in providing security to German naval forces passing along the Norwegian coasts.

36. In the autumn another intercept Kompanie, the 8th, was added to III/Ln. Regt. 5.
37. Training of its new personnel began towards the end of the year, and its eventual duties were to man the D/F Base Atlantic in Norway, to monitor Allied North Sea convoys and to watch for new British and Russian traffic on the northern front.
38. At the end of the year W-Leit 5 at Oslo was renamed 14/Ln. Regt. 5, whilst W-22 at Husum became 15/Ln. Regt. 2.
39. Communications facilities of 14/Ln. Regt. 5 were further increased during 1942, and at the end of the year consisted of the following:-
1 Teleprinter line to Gefechtsstab of Luftflotten Kdo. 5.
1 Teleprinter line to G.A.F. exchange, Oslo.
1 Teleprinter line to Naerland.
1 Teleprinter line to Husum.
1 Teleprinter line to Berlin.
1 Teleprinter line from Naerland to Husum.
1 Telephone line to G.A.F. exchange, Oslo.
1 Telephone line to Ln. Regt. 5.
40. The teleprinter line between Naerland and Husum which had been
established in 1941 was used on occasions for D/F squad traffic, but as
the same line had to be used for all other purposes this was not entirely satisfactory.

8/LN. REGT. 5.
41. The training and expansion of 8/Ln. Regt. 5 continued until the spring, when the 3rd Zug was ready for operations and was sent to Svanvik. Two D/F Adcocks were constructed so that both East and West D/F'ing could he carried on simultaneously.
42. An advance Trupp of the 8th Kompanie was sent to investigate the terrain in the Alta-Bardufoss area with a view of determining a final position for intercept operations. Bardufoss was found suitable so far as convenience and communications were concerned, and two Züge of the Kompanie soon followed.
43. Intercept Trupps of 8/Ln. Regt. 5, with D/F sets at Svanvik, Bodö and Örlandet, were put to covering all Allied W/T and R/T traffic in the North Sea and from Iceland Base and North Sea convoys. The Kompanie was also commissioned by W-10 to intercept all U.S. traffic, the results of which were to be transmitted to W-10 direct and without preliminary evaluation.
44. At times the Kompanie produced excellent results, especially in the interception of unknown U.S. traffic, but operations in general suffered from frequent atmospheric disturbances and a lack of any results which had value for immediate operations.
45. The Zug at Svanvik enjoyed far more favourable conditions than
the unit at Bardufoss; besides the valuable work which it performed in
following North Sea convoys it investigated radio conditions in the
northern area. Its assistance and advice were sought for important
tactical operations in the area.

46. As already stated, the main function of the D/F Base Atlantic was to D/F or plot aircraft of 15 and 18 Groups, with a secondary function of D/F'ing unknown radio stations.
47. Inadequate communications between Oslo and Brest, however, made the immediate use of the information from Brest impossible, its only advantage being in its value for subsequent confirmation.
48. On the whole, the Base proved its worth as it supplied Fliegerführer Atlantik and B.d.U. with regular intelligence on strength, tactics and area of operation of convey escorts and of the aircraft of 15 Group, besides, providing B.d.U. with data which often led to successful U-boat attacks.
49. During the year the communication facilities of the Örlandet, Bodö and Svanvik D/F sites remained unsatisfactory, but nevertheless they contrived to make valuable contributions to the intelligence picture.

50. In the course of the year an intercept cover was put on the Anglo-Swedish courier service, and the monitoring was developed to such
an extent that daily reports on numbers of aircraft operating, bases
and, towards the end of the following year, the squadron strength.

51. In the spring, W-10 ordered Husum to undertake the interception of all Allied transatlantic ferry traffic in the North and East Atlantic; the results were to be evaluated by 14/Ln. Regt. 5 at Oslo. The object was to establish the approximate daily figures of aircraft ferried, their density on the various stretches of the outward and return flights, and the types of aircraft employed for varying purposes.
52. Results were teleprinted daily and also distributed in monthly reports.

53. The breaking of Syko messages was carried out by 15/Ln. Regt. 2 at Husum until Syko was dropped in the middle of 1943. When A.R.C. was
introduced considerable initial difficulties were encountered, but by the end of the year some measure of success was achieved and was further
increased during 1944. These results were used strategically but never

54. In the course of the year the Kompanien at Oslo, Naerland and
Bardufoss were equipped with transmitters in case of breakdown in
landline communication. 15/Ln. Regt. 2 became the relay station for the
re-transmission of messages to superior and related signals intelligence
units in the Reich.


55. The year saw considerable changes in the G.A.F. SignalsIntelligence service as a whole in its attempt to create a homogeneousorganisation. The units in Norway brought into the scheme were renamedas follows:-

14/Ln. Regt. 5 became 1/Ln. Abt. 355.
8/Ln. Regt. 5 became 2/Ln. Abt. 355.
9/Ln. Regt. 5 became 3/Ln. Abt. 355.
15/Ln. Regt. 2 became 5/Ln. Abt. 357.
56. At the same time W-10, the controlling station in the Reich, was renamed Leitstelle der Funkaufklärung.
57. As an anti-invasion measure a mobile listening Zug was created, consisting of a contingent of W/T and R/T operators and evaluators. The unit was responsible to the Fliegerführer and was to be ready to operate at the focal point of an invasion attempt.

58. The intercept station set up during 1943 at Bardufoss and manned by 8/Ln. Regt. 5 (2/Ln. Abt. 355) had shown only partially satisfactory results due to bad reception conditions. The changing war situation made the station redundant as the unit at Svanvik was sufficient for the Northern area so that in the spring the Bardufoss station was moved to Halden.
59. At the same time 15/Ln. Regt. 2 (5/Ln. Abt. 357) was becoming
monopolised by the Leitstelle der Funkaufklärung for duties in defence
of the Reich, and consequently became of less value to signals intelligence in Norway.
60. After the Allied invasion in France the D/F Base Atlantic suffered the loss of its left wing at Brest and then the loss of the Svanvik base through the evacuation of Northern Norway. In the course of 1944 the entire strategic evaluation of Coastal Command traffic was taken over by the evaluation Kompanie of the Leitstelle der Funkaufklärung which was supplied with intercept data by 5/357 at Husum.

61. The experiments which had been made during 1941 and 1942 with
the object of intercepting Allied V.H.F. traffic were finally abandoned
in 1944, although the increasing weight of 16 and 18 Group attacks made
the use of V.H.F. receivers on the West coast more necessary than ever.
62. Changes which took place in the W/T traffic of 18 Group during 1944 caused some difficulties to the Germans, but on the other hand the combined use of R/T and W/T by Allied forces approaching the Norwegian
coasts restored the possibility of obtaining vital intelligence.
63. In such cases as the latter, the W/T intercepts could not be used for direct fighter control but a running commentary on events could be passed to the fighter control officer, detailing direction, probable intentions, tactics and strength.
64. During the year, 2/Ln. Abt. 355 at Halden was engaged in such tasks as covering U.S. W/T traffic and R.A.F. Bomber Command tactics for the benefit of O.K.L. W/T traffic of T.A.F. aircraft was also covered for practice, and 16 Group was intercepted when it operated against the South Coast of Norway. The Kompanie later covered training and part of the coastal network, as well as D/F’ing minelaying and supply dropping activity in the Norwegian area.
65. After the re-organisation of the G.A.F. signals service early in 1944, the radio command stations (Funkbefehlsstellen) established at the divisional and sector reporting centres for the use of the radio observation and jamming services were also used by the Signals Intelligence units for the relaying of messages to higher authorities. At the same time efforts were made to develop the tactical evaluation organisation to the utmost; to that end a close co-operation with radio observation (Fu.m.B.), aircraft reporting and jamming services was achieved.
66. The monitoring of fighter O.T.U.'s in the U.K., which had continued since 1940, came to an end in the spring of 1944 when those units converted to V.H.F. At the same time a fuller cover was put on long range reconnaissance training traffic which was closely connected with the increasingly important North Sea convoy traffic.
67. The latter traffic provided intelligence on tactics, state of development, strength in carrier aircraft and the nature of carrier manoeuvres. To deal with the increase in this convoy traffic a liaison officer was attached to Fliegerführer 5 at Bardufoss and an R/T intercept Trupp was established at Tromsö; R/T operators had already been posted to the D/F squads established at Bodö and Örlandet for the purpose of intercepting R/T traffic of carrier aircraft.

68. The radio D/F squad traffic (Funk-Peilkommandoverkehr) instituted at the beginning of the year proved more and more important for assisting the evaluation of 18 Group and Northern convoy traffic and produced invaluable results. An H/F Adcock was set up at Jessheim to supplement the Halden Kompanie's efforts in monitoring Allied Air operations in the Skagerrak, Kattegat and Oslo Fjord and act as alternative D/F base to that at Naerland.
A.D.I.(K) and S. D. Felkin
U.S. Air Interrogation. Group Captain.
14th November 1945.
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German countermeasures against allied radar jamming

SECRET A. D. I. (K) Report No. 356/1944

1. The following information, which is believed to be fully reliable,
has been obtained in the main from a P/W who had been in charge of Flak
Würzburg positions on the Cherbourg Peninsula.
2. Interrogation has been carried out in co-operation with A.D.I.(Sc),
but this report deals only with the general principals involved,
technical details of circuits and instruments having been passed to
3. Ever since the summer of 1942, the Germans have been alive to the
possibility of electrical jamming of ground radar, and have had
countermeasures under consideration. In the autumn of 1942, amongst
other measures, instructions were issued to units using the Würzburg-D
to remove the revolving dipole if electrical jamming were encountered,
and to replace it with the fixed type dipole aerial from the
4. In January or February 1943, instructions were issued which stated
categorically that electrical jamming was expected shortly to begin, and
detailing countermeasures called by the code names "Stendal A" and
"Stendal B", the latter employing a modification to the set known as
"Goldammer"; these proved reasonably satisfactory.
5. The use of "Window" took the Germans completely by surprise and was
at first almost 100% effective. No countermeasures were available and
entire Flak batteries were put out of action. At first the Radar
operators were told that they must somehow learn to distinguish the
bomber formations from the "Window" reflections, but in practice it was
found that only the most experienced operators were able to do this, and
then only occasionally.
6. Countermeasures were evolved and introduced fairly quickly, and
these are detailed below. All Würzburg instruments in the Cherbourg
Peninsula are stated to have been equipped with the necessary
modifications at the time of the invasion.
7. The German authorities maintain that these countermeasures are 80%
effective, but the present P/W considers that 50% would be a more
accurate figure, since one or other of the special modifications to the
Würzburg is frequently used. Another point mentioned was that even these special modifications were apt to fail, or at least to prove
unsatisfactory, if "Window" was used in very large quantities.
8. Since the introduction of these new countermeasures, the Stendal
procedures have become obsolete and are no longer used.

9. The Nürnberg procedure is a countermeasure against "Window” invented by Stabsingr. HOFFMANN of Flak Artillerie Schule III at Heiligensee.
10. With this procedure, the Würzburg is modified so that variations of
signal strength due to rotation of the enemy aircraft's propellers make
a note which is audible in the headphone, thus enabling the operators to
distinguish between the aircraft and “Window".
11. An improved version of Nürnberg, known as Nürnberg 7, which is less
fatiguing to the operators, has also been developed.

12. This enabled operators to distinguish between fast and slow moving
echoes, and so permits differentiation between aircraft and "Window" or
permanent echoes.
13. The blip on the Cathode ray tube appears as a blob of light
resembling a louse, extending over both sides of the time-base.
NOTE:- Captured wax stencils of the original German instructions for
the use of the Nürnberg and Würzlaus procedures were received from
Normandy after the above interrogation had been completed, and fully
confirm P/W’s statements.
The stencils have been rolled off, and copies are being sent as an
Appendix to this report to A.D.I.(Sc), and to the other departments
marked with a star on the distribution.

14. This countermeasure to "Window", is achieved by a modification
which operates by virtue of the sharper wave front obtained from a true
target blip compared with the more gentle sloping of a "Window" blip.
P/W stated that this procedure was used in conjunction with Nürnberg and
Würzlaus, but was unable to give full details. He claims that Taunus is
also effective against jamming by means of noise modulators.

15. Fakir is the term applied when the split presentation both on the
bearing and elevation tubes is made to appear on two separate traces
placed opposite to each other and nearly a centimetre apart, as shown in
the sketch below.
16. This double trace presentation was usual with Würzlaus before the
introduction of Taunus; with the introduction of the latter, the use of
Fakir has become essential if clear readings are to be obtained on the
cathode ray tube.
Normal bearing "Fakir" bearing
Presentation with presentation with
Würzlaus Würzlaus

17. The Wismar procedure is a counter to electrical jamming, achieved
by means of a change of wavelength.
18. For purposes of this procedure the original Würzburg frequency,
which this P/W believed to be 600 Mc/s., was separated into two or three
bands, each comprising three separate frequencies as follows:-
Frequency Al - 3 Mc/s. above A4.
Frequency A4 - Original frequency,
Frequency A7 - 3 Mc/s. below A4.
A second frequency band, Bl, B4 and B7, was also employed, in which B4
was 30 Mc/s. below A4, and B1 and B7 were respectively 3 Mc/s. higher
and lower than B4.
19. It was intended that there should be third band "C" below the "B"
band, but this has not yet been introduced, as existing transmitters
cannot operate so far below the original frequency.
20. A new local oscillator, known as the "Michael Local Oscillator",
which is easily tuneable, has been introduced for the Wismar procedure,
and nearly all Würzburg-D in the Cherbourg area were equipped with this.

21. A captured document, which has been handed to A.D.I.(Sc), gives
details of an anti-jamming device known as "Westerwald", which is
applicable to Freya and coast-watcher equipment.
22. In effect, this adapts the Taunus technique as used on the Würzburg
to Freya and coast-watcher. Westerwald is the name of the mountainous
country in Germany just north of the Taunus region.

FuGe 25.
23. P/W states, that the Würzburg attachments intended for the FuGe 25
(I.F.F.) procedure have not been fitted for a long time, and that more
recently the frames for these have also been removed in the Cherbourg
area. He states that the FuGe 25 was formerly called by the code name

24. These apparatus, which are developments of the Würzburg, have been
reported in A.D.I.(K) 12/1944, paras.18-26, and A.D.I.(K) 141A/1944,
paras.24-25. The present P/W refers to them under the numbers 40 and 41
respectively. He states, however, that they are complicated and very
expensive, and have hardly been brought into use.
A.D.I.(K) S.D. Felkin
16th July, 1944 Wing Commander
Anlage 4.
Gegenmaßnahmen bei Störung
der Funkmessgeräte (Flak)
Im Fall von Feindstörung der Funkmessgeräte (Flak) sind sofort je nach Art der Störung die
"Wismar" Gemäss L.Dv. 400/30
"Standal" Teil I ‐ IV
und "Würzlaus"
Bis zum Erscheinen der Vorschriften "Nürnberg" und "Würzlaus" sind diese beiden Verfahren wie folgt
I. Nürnberg
A. Begriffsbestimmung
Der Sonderbetrieb "Nürnberg" ermöglicht das Suchen und Auffassen von Flugzielen durch
Funkmessgerät (Flak) 39 T bei Störung durch Folienabwurf.
Das Verfahren beruht darauf, dass die von einem Flugziel reflektierte Energie periodischen
Schwankungen unterworfen ist. Diese erzeugen in den Kopfhörern eines Hörzusatzes einen
Brummton von 50 ‐ 150 Hz.
Die von Folien reflektierte Energie ist unregelmäßigen Schwankungen unterworfen. Diese erzeugen
in dem Hörzusatz ein zischendes und fauchendes Geräusch, das sich von dem Brummton der
periodischen Schwankungen deutlich unterscheidet.
Der Brummton eines Flugzeuges ist nur dann hörbar, wenn das Flugzeug entfernungs‐und
winkelmässig ungefähr angemessen ist.
Bei genauer Ortung ist der Ton am lautesten (Maximum).
Des Verfahren "Nürnberg" ermöglicht also eine akustische Ortung, wenn die gestörten
Entfernungsbereiche auf dem Übersichts‐ und Entfernungsfeinmessrohr ein Zielzeichen nicht oder
nur undeutlich erkennen lassen.
B. Geräte teile und Arbeitsweise des Sonderbetriebes "Nürnberg"
Der Hörzusatz "Nürnberg" ist in die D‐Stufe des Richtgerätes eingebaut. Die auf "Nürnberg"
umgerüsteten Bausteine tragen auf der Vorderseite ein "N".
Auf der Vorderseite des Richtgerätes sind 3 Anschlussbuchsenpaare für die Kopfhörer des B 1, B 2
und B 3 angebracht. Der Sonderzusatz "Nürnberg" ist bei Schalterstellung E + S immer
betriebsbereit. Eine Überprüfung der Betriebsbereitschaft ist möglich durch den Tastknopf in der
B‐Stufe des Richtgerätes. Das Suchen des Flugziels hat bei stehendem Dipol zu erfolgen, weil der
umlaufende Dipol im Hörzusatz ein Geräusch erzeugt, das die Feststellung des Tonmaximums
erschwert. Sind nach der akustischen Ortung Zielzeichen auf dem Übersichts‐und
Entfernungsmessrohr festzustellen, dann kann der UmlaufdipoI wieder eingeschaltet werden.
Blatt 2 zu Anlage 4
In diesem Fall kann die Winkelmessung durch "Sonderbetrieb Winkelmessung" und die
Entfernungsmessung durch "Sonderbetrieb Entfernungsmessung" erfolgen. Das Peilverfahren
dient lediglich als Hilfsmittel zum Suchen und Auffassen von Flugzielen, ist jedoch zur Ermittlung
von Schiessunterlagen nicht geeignet. Eine Erschwerung tritt ferner dadurch ein, das benachbarte
Funkmessgeräte (Flak), (vornehmlich Funkmessgeräte (Flak) 41 T) ein starkes Knarren im Hörzusatz
erzeugen, wodurch die Hörkennung von Flugzielen erschwert bzw. unmöglich gemacht werden
C. Bedienungsanleitung für Senderbetrieb "Nürnberg“.
1.) Überprüfung des Hörzusatzes „Nürnberg“
B 2 legt den Kopfhörer um,
schaltet den Umlaufdipol aus und
stellt den Drehknopf "Pot" auf "Null".
B 1 stellt den Dunkelpunkt auf eine festzeichenfreie Stelle des Entfernungsbereiches.
B 2 dreht an der oberen Schlitzschraube in der D‐Stufe solange nach rechts, bis er ein knatterndes
Geräusch hört, dreht dann die Schraube, so weit nach links, bis dieser Ton gerade verschwindet.
Drückt auf den Tastknopf auf der rechten Seite des Richtgerätes und ruft, wenn er im Kopfhörer,
einen tiefen Brummton hört:
"Hörzusatz betriebsbereit! "
2.) Exerzierordnung für die gefechtsmäßige Anwendung des Sonderbetriebes "Nürnberg"
Flugziele im Störzeichenbereich nicht feststellbar.
Sind Zielzeichen auf den Braunschen Röhren nicht feststellbar, so sind die Winkel ‐und
e‐Messung allein nach dem Gehör durchzuführen. Es werden dabei alle drei Werte nach dem
akustischen Maximum ermittelt.
B 2 ruft bei Auftreten eines Störzeichenbereiches aus:
"Feindstörung durch Folien!"
Kann er kein Zeichen im Störbereich des Übersichtsrohres erkenne, ruft er nun:
"Auffassen nicht möglich!"
M.F. befiehlt.
"Hörzusatz! "
B2 legen Kopfhörer um.
B1 dreht am e‐Grobtrieb die Entfernung des Störzeichenbereiches langsam durch, beobachtet die
Störzeichen und achtet auf den Ton im Kopfhörer.
Hört er neben zischenden und fauchenden Geräusch einen tiefen Brummton, so bringt er diesen am
e‐Feintrieb auf in Maximum.
Blatt 3 zu Anlage 4
B 2 betätigt gleichzeitig das Höhenrichthandrad und bringt durch Peilen den im Kopfhörer hörbaren
Brummton auf größte Lautstärke. Dadurch ist das Ziel grob geortet (Messfehler bei feststehendem
Dipol; zur Verwendung als Schiessunterlage nicht geeignet).‐
Das Flugzielzeichen ist noch in dem Störzeichenbereich erkennbar.
Der Hörzusatz dient in diesem Fall lediglich als akustisches Hilfsmittel zum eindeutigen Erkennen
des Flugziels. Ist dies möglich, kann mit Hilfe des "Sonderbetriebes Winkelmessung“
weitergearbeitet werden. Ist auf Grund der akustischen Ortung auf dem Übersichts‐und
e‐Feinmessrohr als Zielzeichen erkannt, rufen B 1 und B2 aus:
"Ziel erkannt"
M.F. befielt:
"Sonderbetrieb Winkelmessung! "
B2 schaltet den Umlaufdipol wieder ein.
B1 hält das erkannte Zielzeichen auf dem Dunkelpunkt.
B2 und
B3 messen gemäß "Sonderbetrieb Winkelmessung".
Verschwindet das Zielzeichen auf den Röhren kurzzeitig, so führen B1 und B2 bei umlaufendem
Dipol das Ziel akustisch weiter bis das Zielzeichen wieder sichtbar ist.
II. "Würzlaus".
A. Begriffsbestimmung und Erscheinungsform.
Das Verfahren "Würzlaus" dient zum Auffassen und Anmessen eines Flugzieles bei Feindstörungen
durch Abwurf von Folien.
Das Verfahren "Würzlaus" ermöglicht die bildliche Unterscheidung der reflektierten Energie eines sich
bewegenden Zieles (Flugzeug) und eines festen Zieles (Düppelwolke). Durch Verwendung eines
eingebauten zusätzlichen Hilfssenders wird erreicht, dass sich das Zielzeichen durch eine besondere
Formgebung von den Störzeichen unterscheidet.
Festzeichen und Metallfolien geben bei Sonderbetrieb "Würzlaus" auf dem Übersichtsrohr sich
schlängelnde Zeichen. Die Zielzeichen von einem sich schnell bewegenden Flugziel erscheinen als
eiförmige ausgefüllte Zeichen (sogenannte Würzlaus).
Auf den Richtrohren erscheinen nach Umschalten auf "Würzlaus" zwei Lichtstriche, auf denen die
Ablenk‐und Störzeichen kehrbildlich einander gegenüber stehen. Ein Zielzeichen ist dann genau
angerichtet, wenn die beiden, einander gegenüberstehenden Flugzielzeichen (Würzlaus) gleich groß
sind. Auf dem e‐Feinmessrohr erscheinen ebenfalls 2 Lichtstriche, aber die Stör‐und Zielzeichen
kommen nur auf dem oberen Lichtstrich zur Anzeige. Das Ziel ist dann genau angemessen, wenn der
Dunkelpunkt die "Würzlaus" halbiert.
Blatt 4 zu Anlage 4
B. Geräteteile zur Bedienung des Sonderbetriebes "Würzlaus".
Zum Sonderbetrieb "Würzlaus" sind folgende Geräte und Geräteteile am Funkmessgerät erforderlich:
1.) ein Hilfssender H.S. 62/65 "Michael" (am Ausleger links neben dem Richtsitz)
mit Bedienungsknopf "Ankopplung" und Bedienungsknopf "Abstimmung",
2.) ein H.F.‐Kabel vom Hilfssender zum Senderüberlagerer
(führt durch den Ausleger in den Sendeempfangsgeräteschrank und ist
mit dem H.F.‐Stecker in den Senderüberlagerer eingeführt),
3.)Drehknopf zum Ein‐und Ausschalten der Kehrbildanzeige
auf der rechten Seite des Richtgerätes (Mittelteil),
4.) Schlitzschraube (K) zum Nachjustieren des Kreisdurchmessers
auf dem Übersichtsrohr auf der rechten Seite
des Richtgerätes (Mittelteil),
5.)Senderüberlagerer, die für den Sendebetrieb "Würzlaus"
ausgerüstet sind, tragen ein "W" auf der Frontplatte.
C. Bedienungsanleitung für Sonderbetrieb "Würzlaus"
a. Herstellen der Messbereitschaft.
Allgemeines: Das Funkmessgerät 39 T(D) wird nach
der L.Dv. 400/8a eingeschaltet und abgestimmt.
Mit dem Einschalten des Funkmessgerätes (Flak) ist auch der Hilfssender eingeschaltet. Die
Justierung des Dunkelpunktes auf dem Übersichtsrohr entfällt.
Die Schraube "Dunkelpunkt" bewirkt lediglich nur eine Verschiebung der
Ablenkzeichen auf den Bildröhren.
"Abstimmen des Hilfssenders".
B2 messen Standziel genau an
B2 schaltet Kernbildanzeige ein
durch Umlegen des Schaltknopfes
im Mittelteil auf der rechten Seite des
Richtgerätes von "N" auf "S";
überzeugt sich, daß Bedienungsknopf "Ankopplung" auf Linksanschlag steht
regelt Sprühen auf dem Übersichtsrohr auf 2 mm
durch Drehknopf "Pot" (Stellung 2 ‐ 3).
dreht Bedienungsknopf "Ankopplung" auf Rechtsanschlag
stellt Lichtstriche auf dem Seitenrichtrohr (gleichzeitig Höhenrichtrohr)
auf größten Abstand
durch Drehen am Bedienungsknopf
"Abstimmung" am Hilfssender.
Blatt 5 zu Anlage 4
Noch B2
bringt Lichtstriche auf 1,5 cm Abstand
durch Linksdrehen des Bedienungsknopfes "Ankopplung"
justiert Durchmesser des Lichtkreises auf dem Übersichtsrohr nach
durch Drehen der Schlitzschraube
im Mittelteil auf der rechten
Seite des Richtgerätes.
Hilfssender ist abgestimmt, wenn Festzeichen als
sauberer Schlängel auf den Richtröhren erscheint.
B 2 meldet: "Hilfssender abgestimmt".
schaltet wieder auf "Normalbetrieb"
durch Umlegen des Schaltknopfes im Mittelteil auf der rechten
Seite des Richtgerätes von "S" auf "N".
schaltet Sonderbetrieb "Würzlaus" aus
durch Drehen des Bedienungsknopfes "Ankopplung" auf
b. Gefechtsmäßige Bedienung.
Beachte, dass der Abstand der Lichtstriche im Seitenrichtrohr stets 1,5 cm betragen muss.
Durch Änderung der Empfindlichkeit durch den Drehknopf "Pot" ändert sich auch dieser
Abstand. Durch Drehen an dem Drehknopf "Ankopplung" am Hilfssender müssen daher
Lichtstriche laufend auf 1,5 cm Abstand gehalten werden.
B 2 beobachtet das Übersichtsrohr. Bei Feindstörung durch Folien ruft er aus:
"Feindstörung Folien"
M.F. befielt " Sonderbetrieb "Würzlaus".
B 2 schaltet Sonderbetrieb "Würzlaus" ein
durch Drehen des Bedienungsknopfes "Ankopplung" auf
schaltet Kehrbildanzeige ein
durch Umlegen des Schaltknopfes im Mittelteil auf der rechten
Seite des Richtgerätes von "S" auf "N".
sucht in der vermutlichen Richtung
regelt die Empfindlichkeit laufend nach
durch Drehen am Drehknopf ''Pot" .
bringt Lichtstrich auf normalen Abstand von 1,5 cm
durch Bedienungsknopf ''Ankopplung'' am Hilfssender
Blatt 6 zu Anlage 4
Noch B 2
beobachtet das Übersichtsrohr.
Beim Erkennen einer ''Würzlaus'' ruft er aus:
''Aufgefasst in 130!"
B 1 stellt die von B 2 ausgerufene Entfernung
durch den e‐Grobtrieb ein
hält laufend die ''Würzlaus" auf den Dunkelpunkt
durch Drehen am e‐Feintrieb.
B 2 u.
B 3 messen den Seiten‐ bzw. Höhenwinkel,
in dem die beiden kehrbildlichen
Würzläuse auf gleicher Größe gehalten werden.
Bei genauer Einstellung rufen sie aus:
''Seitenwinkel (Höhenwinkel) ‐ Null 1''.
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Old 5th November 2018, 01:26
Bruce Dennis Bruce Dennis is offline
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SECRET A. D. I. (K) Report No. 357/1945.

Navigational Aids.
1. This report is the second of the series dealing with radio and radar equipment in the Luftwaffe.
2. As in the case of the first of the series (A.D.I.(K) 343/1945) dealing with Blind Landing and Airborne Communications Equipment, it is based on interrogation of General Nachrichtenführer MARTINI, Director General of G.A.F. Signals, and a few important members of his staff, and has been supported by a file of current papers which were in the possession of the General’s Chief of Staff.
3. An index of the numerical designations of the navigational equipment mentioned in this report appears in Appendix I.
4. For convenient reference, a translation of the document entitled "Funkausrüstung der Flugzeugmuster, Notprogramm" (signal Equipment in the G.A.F. - Emergency Program) - item 45/99 ff in A.D.I.(K) Documents List 45/9 - which has also appeared as an Appendix to A.D.I.(K) 343/1945, is reproduced as Appendix II to the present report but the list of equipment contained in that document has been omitted as Appendix I gives a fuller list.

5. Throughout the course of the war, the general standard of German navigational training was undoubtedly inferior to that of the Allies. A simple form of navigation was taught but navigators track plotted only and relied on W/T aids and in particular positioning by means of loop fixes as the main basis for their navigation.
6. During the early part of the war extensive use was made of Knickebein and other beam systems, but later this form of navigational aid gave way to the "Y" control system (better known by the Allied codeword Benito) and "Egon".
7. Sonne was universally accepted as an outstanding success and from the time of its inception in 1942 research was continuously directed towards overcoming its imperfection, in particular the range limitation. Komet was a typical example, of attempted improvement on these lines
8. The Germans were patently backward in the field of pulse systems and the majority - if not all - of their navigational aids of this type were copied from Allied methods.
9. The fear of the Allied countermeasures was much to the fore during the last two years and considerable research and efforts was devoted to offsetting such interference and to perfecting systems which would reduce and if possible preclude the danger of jamming. Another factor always present in the minds of those responsible for tactical navigational requirements was that the apparatus must be as light and small as possible because of the limited space available in German aircraft.
10. During the last stages of the war, and as a natural consequence of German air policy, being forced to concentrate on the defensive, thereby involving almost exclusive use of fighter power, a great deal of attention was devoted to the development of simple navigational aids suitable
for single-engine aircraft of which Rübezahl was a typical example.

PeGe (Peil Gerät) 6.
11. PeGe 6 was the successor of PeGe 5, the standard loop D/F, set in use at the beginning of the war, and. operated on 150 - 1200 kc/s (2000-250 meters). It provided automatic D/F facilities, the W/T operator merely having to tune to the signal and the "answer" being produced on a course indicator.
12. In the opinion of P/W, who was responsible for operational requirements in the navigational field and who had had fairly extensive navigational experience with K.G.40, PeGe 6 was less reliable than the manually-operated PeGe 5 as the automatic D/F facilities could not distinguish between the true signal and jamming and were apt to record bearing midway between the two if they were near together. The human ear was much more acute and could distinguish the minimum of the real signal from that of the "phoney” one. It had the further disadvantage that it was a heavier piece of equipment than the manually operated set.

FuGe 141
13. The FuGe 141 operating on a frequency band of 58.0 - 59.2 mc/s was a receiver with a D/F loop fitted to Air Rescue aircraft used for homing on to the NS 4 emergency radio set carried on the chest by pilots.
14. The NS 4 had a flexible steel tape aerial and batteries which gave it an endurance of 2 to 2,5 hours.

FuGe 142.
15. The FuGe 142 using the 2000 - 250 metre band was a small D/F battery set for use in emergency in the event of failure of the aircraft' s electricity supply.
16. The FuGe 142 had a manually-operated loop and its accuracy was only 10° to 15°.
17. When the P/W who, in October 1944, took over the navigational tactical requirements first made its acquaintance, he discovered that the designer of the emergency set, while having the laudable object of assisting a crew in dire emergency when they where probably well and truly lost, had omitted to include any sensing arrangement. The set was, therefore, quickly scrapped as being as much of a danger as an aid.

FuGe 145
18. The FuGe 145 was a simple type of D/F set in development for use in single-seater aircraft. It was for use with M/F beacons and was designed for use by coastal reconnaissance aircraft, as for example the Do.335, so that they could obtain a bearing when flying at low level.
19. It was much lighter than the PeGe 6 and had no automatic facilities, but was very easy to operate. P/W had thought that it might ultimately supersede the PeGe 6 for other types of aircraft.

Suggested loop for fighter aircraft
20. The research centre at Rechlin had been asked to examine a rough type of loop for singleseater fighter aircraft, which would consist of a loop built into the pilot' s helmet. It was thought that this would enable the pilot to establish the general direction of a beacon by movements of
his head and without recourse to the use of a compass.
21. This idea was tried out and seemed promising, but was never fully developed.

22. The Schwanboje was a waterborne V.H.F. beacon dropped by parachute and originally used by K.G.40 for marking convoys or submarines. In the autumn of 1944 a 1ine of Schwan buoys was used to aid the He.111's when launching V-1’s from the North Sea against this
23. The beacon consisted of a frame aerial and transmitted on a wavelength which could be homed on by the FuGe 17, the standard equipment of K.G.40 in 1942 when the Schwanboje came into use.
24. The set was powered by accumulators and had a live of five hours; by the means of a clockwork device it could be pre-set before release so that it ran for a testing period immediately on release and later started up again after a prescribed interval governed by the expected time of arrival of the homing aircraft. The buoy was fitted with a self-destroying
charge operated automatically.
25. A later type of Schwanboje operated on the 38 - 42 mc/s waveband so that aircraft equipped with the FuGe 162 could also use the system.
26. Biene is the code word for a responder beacon. The idea of responder beacons for homing purposes had only been hit on in 1944 and Bienen to respond to the different airborne radar sets were still under development in 1945. The FuGe 243 - Hohentwiel Biene – had been used by coastal units in Norway, in February or March 1945.
27. Responder beacons were also being developed for use in the Baldur method of navigation (see paragraphs 79, 82 of this report).

28. This was the latest form of the well-known Knickebein working on 30 - 33,3 mc/s and received by E.B.L.3 in the aircraft. It was a mobile station which could be fully erected into operation within a week.
29. A still more mobile unit known as the Bock-Zyklop had been introduced. This could be set up in three days and could be adapted for use on the FuGe 16 frequency although as yet, according to documents, no visual indicator for the FuGe 16 had been developed.
30. The 120 W ground transmitter was called the ???? which gave a beam 0.5° wide and a range of 300 km. at a height of 5,000 meters. The Zyklop systems had been made use of on the Russian front up to the end of the hostilities.

31. The Sonne beacon system which worked on a frequency of 270 - 480 kc/s was received in the aircraft on the FuGe 10. It was considered an extremely effective daylight system but the range limitation was a disadvantage. Fixes could be obtained from ranges up to 1,000 - 1,200
km. Sonne 6 at Quimper which was the most efficient of the Sonne beacons, had been used on an occasion at a distance of 1,400 km.
32. The sectors served by Sonne covered, an angle of 120 – 150°. The beacon was very reliable over the centre sector of 100°, but the error increased progressively towards the edges of the beam in conformity with the sine law.
33. At night errors up to 4° were liable to occur even in the centre of the sector of the beacon and no real use could be made of it.

34. To improve the Sonne beacons both in range, and accuracy, an experimental system working on the same principle, but on 3000/6000 kc/s was tried out in 1942. The shorter wave transmission did not prove very reliable and was given up about the end of 1943.

35. Finally a beacon of the Sonne type under the name "Stern" was designed for use on a V.H. frequency. It, not unnaturally, only gave optical range and was, therefore, of no practical value and was not developed.

36. One P/W had seen documentary mention of Dora which he believed was a navigational aid system and a precursor of Komet. He did not know whether it worked on the same principle but the Komet experimental site at Kolby was on the former Dora site.

37. In 1942 the question of navigation over the Atlantic stood in the limelight . As the He 177 was supposed to be coming into service shortly to enable K.G.40 to reach further West, the need for navigational equipment of longer range became acute.
38. A year or so earlier Professor von HANDEL had categorically stated in a lecture that a long-range navigational system based on pulse would inevitably be extremely inaccurate. In view of Professor von HANDEL's views on pulse systems, an improved form of Sonne which would give much greater ranges and be less susceptible to night effect was given high
39. The system evolved was called "Komet" and experimental stations were erected at Bordeaux and Kolby (see A.D.I.(K) 364/1944). The ground station called for an array of no less than 127 masts and 19 control huts in order to cover a 90° sector. It worked admirably provided a 10° sector only was covered, but as soon as the planned 90° sector was put into operation, mutual interference between the masts arose and the various lobes radiated were no longer of symmetrical pattern, with the result that large errors crept in.
40. Research on this delayed the project considerably. After the invasion when long distance reconnaissance in the Atlantic was no longer practical politics, the Komet system was given up without ever having been effectively used. The development people were the more pleased to dispense with it since it left the German radio research and industry free to deal with other more urgent matters.
41. The beacon was to operate on frequencies of 5000, 9000 or 12,000 kc/s received on the FuGe 10K, and it was estimated that ranges up to 3000 km would be obtained. The system employed was to be similar to that used in the Sonne but instead of obtaining one reading per minute, oscillation of the beam was to be speeded up to give 100 readings par minute.
42. The true bearing of the aircraft was automatically recorded by the FuGe 124 which was known as the Kometschreiber. The recording took the form of a series of vertical lines, one for each reading, printed on a strip of paper. At the same time as the lines were printed the Kometschreiber recorded the section of the swept area in which the aircraft was flying, thus giving what amounted to a rough position.
43. The fine reading was obtained from the length of the recorded lines. Any inaccuracies due to night effect could be easily eliminated by averaging the length of the lines, as recorded, on the paper strip, by eye.
44. Erika was a navigation system (see A.D.I.(K) 364 and 409/1944.) which had already reached the development stage in 1942 but its operational employment was of brief duration and it was soon discarded in favour of Bernhard.
45. Erika was based on the principle of a V.H.F. (30 - 33 mc/s) beam oscillating rapidly over a segment of about 60 – 90°. The beam was phased, a different phase being picked up in different sections of the segment and read off in relation to a standard phase producer in the aircraft. In order to obtain a fix, two such Erika stations had to be received and to receive each station no less than two E.B.L.3's were necessary making a total of four receivers.
46. The range presentation unit in the aircraft, FuGe 121, took the form of a clock-face with a needle indicator and calibrated, P/W thought, from 0 -100. A specially prepared map was required to establish bearing.
47. A disadvantage of Erika was the vulnerability to jamming, interference signals modifying the phase and thereby giving inaccurate readings. The great weight, carried and the bulk of the four receivers, which were particularly cumbersome in the relatively small aircraft in use in the G.A.F. made its widespread use impracticable.

48. This system was first introduced in 1942 for use by bomber aircraft, but was later dropped in favour of the Benito and Egon control systems. With the increasing British jamming during night raids it was reintroduced for use in night fighter commentary (see A.D.I.(K) 125/1945, paras.5 to 29), which it was thought could only be jammed with great difficulty.
49. The term “Bernhard” was used for the ground stations whilst the airborne recording equipment was called Bernhardine or FuGe 120. The latter made use of the E.B.L.3. receiver as the transmissions lay in the 30-33 mc/s band.
50. At the time of the German capitulation, the following three transmitting stations were in operation, the first two, of which could transmit commentary.-
-Thisted, on N.W. coast of Denmark.
-Bretstedt, N. of Husum, Germany.
-Trebbin, S.E. of Berlin.
51. A further station near Breslau had been almost completed when it had to be dismantled on account of the Russian advance. Additional stations were in the course of construction near Kassel, Munich, Pilsen and Vienna.
52. The Bernhardine system was looked upon as a considerable improvement on Erika. It gave 360° coverage as compared to 60/90° with Erika and, whereas from the jamming aspect stray signals could disturb the phase of Erika causing false indication, in the case of Bernhardine,
interference merely resulted in no reading being possible, and furthermore to attain this through 360° a very powerful jamming transmitter flying near the ground station would be needed.
53. The Bernhardine system was not regarded as unjammable but it was thought that use of high power and aerial gain would render jamming by airborne means impracticable.
54. In addition to the E.B.L.3 receiver, the airborne Hellschreiber FuGe 120, also called the Bernhardine, which gave both bearing and commentary was employed. According to P/W the FuGe 120 was large and weighty and the first improvement aimed at was to reduce the weight and provide a set which occupied less space in the aircraft. To this end an attempt was made to eliminate the use of paper strip for the Hellschreiber and a rotating "Folienschreiber" a cellophane paper moving over a sticky carbon surface which constituted a self-eraser - was employed. This projected recording method proved a failure and the use of paper strip had to be reverted to. According to documents the type using paper strip was known as FuGe 120a, and the self-erasing recorder FuGe 120b.
55. A smaller model, the FuGe 120k, to operate on the paper strip principle which constituted the latest improvement, was still in the development stage at the conclusion of hostilities. Previously the ground transmitter broadcast simultaneously from the upper and lower aerial
arrays on two frequencies close enough to one another for them both to be received on one channel of the E.B.L.3. One lobe was used for coarse D/F, the other for fine. The two frequencies were then separated by a filter before being fed into the Hellschreiber. The FuGe 120k was designed for use with a ground transmitter operating only on the coarse D/F frequency. The filter could therefore be dispensed with and considerable weight saved in the airborne set at the expense of some accuracy in D/F.
56. With the loss of D/F accuracy the sharp “V” in the vertical printing indicating the reading (see diagram A.D.I.(K) 125/1945 para.18) became a gap about 4° wide. To facilitate the reading of the centre of the gap by eye, and to reduce the size and weight of the apparatus, the vertical lines referred to above were superimposed on the scale which could then only be read in the gap. This allowed the paper strip to be considerably narrower.
57. The FuGe 120k was designed primarily for use in single seat jet aircraft but was also to be embodied in the Ju.88 where space was at a premium, as soon as sufficient numbers of this set were available.

58. The Hermine system was originally developed, in response to a tactical requirement formulated during the second part of 1942, as a navigational aid for the purpose of giving an approximate bearing to single-engine night fighters engaged on “Wilde Sau” operations.
59. By the time the initial difficulties in development had been overcome Wilde Sau night fighting had almost ceased; it was found however that Hermine could be used to advantage by day fighters, and it came into operational use.
60. An accuracy of ±5° was assumed, but it was found in practice that this could be improved upon to ±3° by experienced pilots.
61. Thirteen or fourteen ground stations were in operation by Easter 1945 which, P/W claimed, gave complete coverage of the Reich. It was intended to fit two Schlechtwetter (bad weather) Fighter Geschwader with the necessary airborne equipment, and this program had been onethird
completed by May 1945. One P/W had heard that ten to fifteen Me.262's of K.G.51 were amongst the aircraft so equipped.
62. The following may be added in modification of the description of the Hermine system given in A.D.I.(K) 125/1945, paras.59 to 62. The Hermine rotating beacon transmits a continuous tone on which is superimposed a speaking clock which counts from 1 to 35, each
figure representing tens of degree. Over an angle of about 15° the continuous tone falls to a minimum and rises again. During this period the voice appears to become more audible and the pilot can estimate where the minimum of continuous tone occurs, and so obtain his bearing from the beacon.
63. The beacon recognition is given by means of a self-evident code name for example, "Berolina” for Berlin – which is spoken by the voice in place of 000°.
64. The airborne equipment is the FuGe 125 consisting of the E.B.L.3 with the Tzg (Telephoniezusatzgerät) which enables the 30.0 - 33.3 mc/s transmission picked up on the E.B.L.3 receiver to be heard in the pilot's headphones. Though the Hermine beacons were fully operational there was a scarcity of FuGe 125 sets, as a result of which practical experience of this system was too limited to judge of its efficiency or to lead to further improved tactical requirements been formulated.

65. All the P/W had heard reference to Ingolstadt and agreed that it was a long-range navigational system.
66. One P/W thought that Ingolstadt was the cover name for a pulse navigation system using hyperbolic curves and similar to British Gee; it was originated by Telefunken in 1938 but was then turned down by the R.L.M. In his recollection the original Telefunken idea derived from
theoretical discussions at an international conference before the war.
67. As mentioned earlier under the heading of Komet, Professor von HANDEL maintained that owing to the incidence of mutual interference between direct and reflected waves the system was impracticable at long range. In consequence of von HANDEL’s view the system was dropped.
68. Much consternation and annoyance was occasioned in 1944, when it was found that the Allies were successfully operating a similar system.
69. Truhe is the cover name used to describe navigational aid system, using ground stations, similar to those of British Gee. In effect the British Gee stations were also used, the airborne sets being almost identical with the British Gee boxes.

70. There is no very distinct difference between "Truhe" and "Hyperbel". The latter term was originally coined to denote our Gee. It was also used when German aircraft equipped with British Gee sets made use of British ground stations.
71. The British Gee chain was used successfully but it was realised that so soon as the Germans lost an aircraft, over England, a change would be made. The German "Y" service monitored the British ground stations to follow any change in Gee phasing and passed advice of such change to their aircraft by W/T.
72. Truhe referred to the German system which was ultimately to cover the 20 to 100 mc/s band and employed various types of ground transmitters including Feuerhilfe, Feuerstein, Feuerzange and Feuerland. All these transmitters could also be used to jam our own Gee, further details of which will appear in a subsequent report on German Radio Countermeasures.
The original 46 to 50 mc/s system was known as Truhe I and the new 30 to 60 mc/s system as Truhe II.
73. A chain of Truhe stations was built around Berlin, primarily for training purposes and there were in addition groups of ground stations in the Schwarzwald and in Pomerania. The last named was intended for operations against Russia and it is not known if the stations were
destroyed before their capture.
74. The airborne sets which were known as FuGe 122 covering 46-50 mc/s and FuGe 123 covering 25-75 mc/s were replicas of the British Gee boxes and according to P/W were equivalent to British R.1324 and R.1355. These German sets were slightly smaller and more compact than the British sets.
75. Truhe was used by F.A.G.2 and K.G.66, but up to the time of capitulation only a few FuGe 122 and FuGe 123 sets had been produced and only one R.F. box for the latter set.

76. The Baldur range-measuring system is comparable to the British G.H. and appears to have been imitated from it. It was referred to by P/W as “Egon in reverse" and was the only navigational system developed by the German by means of which an aircraft could measure distance from a known source as opposed to fixing itself by a position line. As the G.A.F. staff were still thinking in terms of a grandiose bomber policy as late as June 1944, it was intended for use by bomber aircraft for pinpointing targets and for accurate blind bombing.
77. The wavelength employed was in the neighbourhood of 2-4 meters and fell in the SN 2 band.
78. Only two experimental transmitters, both located in Lower Silesia, were erected and one P/W maintained that this system never progressed beyond experimental trials by the manufacturers. It was eventually relegated to low priority owing to the virtual cessation of German bomber operations and the pressure of more urgent demands on radio research and the radio industry.
79. The airborne equipment was known as the FuGe 126 which was made up of a transmitter to interrogate a ground responder beacon, a receiver and a presentation unit. The receiver and transmitter were SN 2 units, though P/W thought they might have been slightly modified for use with Baldur.
80. From documents, the presentation unit appears to have been a modification of the Würzburg range measurement tube, and the accuracy is given as ± 100 meters at all ranges, but this was thought to be purely theoretical and P/W doubted whether it would have been possible to achieve this accuracy in actual practice.
81. A smaller airborne set, the FuGe 126k (k = klein = small) was built for use by single-seat aircraft. In reducing the size and weight of the set, and making it pilot-operated, accuracy had to be sacrificed. P/W, who was responsible for putting up the tactical requirements, considered a clock-face presentation to be the ideal solution. It was expected that the accuracy of the FuGe 126k would then be of the order of 500 meters independent of range.

Baldur - Truhe
82. It was planned to experiment on a combination of Baldur and Truhe (Gee) for use by bombers. The intention was to use a hyperbolic grid line of Truhe for the target approach. This could be pre-set, and the pilot could fly along it by keeping the blip centralised, and could ascertain his exact position along the line by measuring his distance from a Baldur beacon. This system was considered simpler particularly for a single-seater aircraft, than the method of using two hyperbolic grid lines or two distances from Baldur beacons. The first experimental sets were to be ready in the autumn of this year.

Baldur - Bernhardine
83. A further project was a combination of Baldur and Bernhardine to give simultaneous bearing and range. The range indication was to be obtained by the pilot pressing a knob when the range would appear in kilometres on a dial. This system was suggested for use by both day fighters and bombers.

84. The Benito system of control using FuGe 16, known to the Germans as "Y", is too well known to warrant description. The following paragraphs deal with recent developments.
85. When operating the bomber Benito procedure with the narrow beam. (0.3°) essential for azimuth accuracy, it was easy for the bomber pilot to get on to one of the side lobes in error since these were only about 3° from the main beam.
86. In order to minimise the possibility of mistake and to relieve the pilot of the strain of flying on a beam, an automatic device, the FuGe 28a, was in use which was the improved and final form of the old Y-Gerät of 1941. Documents dated about June 1944 show that it was used in conjunction with FuGe 17, but P/W thought that it had been modified for use with FuGe 16ZY as well.
87. The procedure was that the bomber pilot flew on instructions conveyed over the FuGe 17 until it had been established by ground D/F stations that he was on the true beam, when the code word "Bako" would be given whereupon the pilot would switch on the FuGe 28a which took over control of the automatic pilot and kept him on the beam.
88. P/W gave the accuracy of range measurement with the Bomber Benito procedure as only ± 1 km. at maximum range.

89. The original Egon procedure which involved the use of two Freyas, the one for rough positioning and the other for fine positioning - later became known as "Egon Einstand" (One location) to differentiate from an improved system termed “Egon Zweistand” 90. Egon Zweistand was evolved to offset the inaccuracies in azimuth D/F, and cash in on the range accuracy of radar. With Zweistand a third Freya was introduced, placed some
considerable distance from the other two Freyas in order to give a distance cut. It was intended for use by bomber aircraft operating over England or on long range sea missions.
91. The original Zweistand system, which was first tried out in Italy by a Schlacht unit, was somewhat primitive in that the readings from the extra Freya were telephoned through to the plotting centre and worked out before being plotted on the Seeburg table.
92. To eliminate the delay thereby involved a landline connection was introduced to feed the Freya pulse to the C.R.T., which then had two blips showing ranges from the two Freya sites.
The vulnerability of landline to disturbance and destruction later led to the development of a W/T transmitter and this method was employed successfully in operations.
93. Since the Freya pulse was not strong enough to trigger off the FuGe 25A at ranges exceeding 250 kilometres, it was planned to supplant the Freya by extra powerful Wassermanns, and thereby increase the effective range of Egon Zweistand to 350 kilometres.
94. A further line of development was the provision of a new type of control table giving the exactitude of plotting necessary for pinpoint bombing. This control table, which was under development at Rechlin, made use of complicated mechanical apparatus for accurate projection
of the position of the bomber. One of these tables was destroyed in the course of a daylight air attack on Rechlin in February 1945; two other tables were in existence at the time of the capitulation, and were located somewhere in Western Germany.
95. Egon when first introduced was received with some scepticism by the crews, as it was felt that it was too vulnerable to jamming. After it had been used operationally without being jammed in the attacks on London in March 1944, the procedure was adopted with greater confidence, and it gained a good reputation. As recounted in A.D.I.(K) 343/1945, Egon was
always favoured by the R.L.M. technical development section in preference to Benito control.
96. A drawback of the system was its restricted range at low altitude, which according to P/W was the reason why it was not used in conjunction with V.1 operations.

97. The Nachtlicht system was the first method of control not using R/T speech to be improvised by the Germans, and had been tried out during the raids on London in the spring of 1944.
98. It had been observed that the red signal lamp of the FuGe 25A was illuminated when the aircraft was being swept by a Freya, and it was suggested that use could be made of this as a means of transmitting morse signals from the ground. A Freya operating on a special wavelength, which P/W thought was 2.55 meters, was set up on the Channel coast and was used to send simple instructions to the aircraft attacking London by means of visual morse indications on the lamp of the

FuGe 25A.
99. The primitive method of giving distant control indications was the forerunner of "Nachtfee", "Barbara" and "Barbarossa".
100. Luftkurier was the first development of the Nachtlicht idea. It was primitive device intended to give visual indication to the pilot by means of a pointer which was started and stopped by the reception of pulses.
101. P/W thought that Luftkurier was first tried out by K.G.66 on the Freya band, but it was so easy to jam by the addition of extra pulses that it was never developed.

102. Nachtfee was the term used to describe a system for the transmission of control instructions to a pilot in the beam of the controlling Freya through the medium of a C.R.T. indicator similar to the Lichtenstein range tube. The airborne equipment used was known as FuGe 136 and weighed 12 kg.
103. The original purpose of Nachtfee was, to provide a solution to the jamming of R/T control systems, and it had been used operationally by the Pathfinders of K.G.66 for mines in the Scheldt estuary. It was to be adapted for use by night fighters to overcome our jamming of the
night fighter commentary.
104. Nachtfee was a system using the FuGe 25A as receiver.
105. The presentation screen in the aircraft was inscribed with various commands both on the inside and outside of a circular time trace. There was a stationary zero blip in the 12 o'clock position, and when an instruction was radiated the pulses received caused a second blip to emerge from the first and travel round the C.R. tube in a clock-wise direction, presumably by a slight change in p.r.f. This blip came to a stop and the command corresponding to its position could be read off on the inside of the time trace where a total of about eight different instructions were inscribed. It took from one to two second, for the blip to travel round the tube.
106. It was thought that the further eight commands inscribed on the outside of the time trace were denoted by the blip making a complete circle starting round a second time before coming to rest at any one of the eight sectors. In this way a total of sixteen different orders could be given. For night fighters such instructions as "turn left/right", "climb", "dive”, etc. appeared on the inner side and figures for transmitting bearing on the outer side of the trace.
107. This system was used operationally, but it was found that, apart from the susceptibility to jamming, other pulse transmissions could interfere by unlocking the system and thereby cause wrong positioning of the indicator blip.
108. Another pronounced objection to the Nachtfee lay in the fact that it was necessary for a member of the crew to watch the C.R.T. indicator uninterruptedly for missing one blip indication might give the message a false value. It was not therefore possible to use it in singleseater aircraft.

109. This apparatus, also called FuGe 138, consisted of an attachment to the FuGe 25A receiver and only weighed 2 kg. This unit contained an audio filter which allowed the pilot to hear morse signals superimposed on the Freya interrogator transmission if they were emitted on a suitable audio frequency usually about 800 cycles. By keying other morse signals on different audio frequencies and equipping aircraft with suitable filters, more than one aircraft could be controlled by a single Freya.
110. Barbara was to be used for Egon control of ground-strafing aircraft and bombers but not for night fighters.
111. In the Germans' opinion there were three disadvantages, namely that the Allies could intercept and make use of signals so transmitted, that the aircraft had to be in the beam of the Freya if it were to receive, and so an aircraft "lost" by the Freya owing to jamming could not be communicated with and finally that, though intended for single-engined aircraft, fighter pilots rarely had sufficient command of morse to be able to use this type of control.

112. Barbarossa was a set designed to meet the same requirements as Barbara but to remedy two of the drawback mentioned in the last paragraph.
113. The instructions to the aircraft were to be transmitted by code pulse modulations which were passed through a "pulse filter" in the airborne set and a written indication obtained on a Hellschreiber. The pulse filter and Hellschreiber unit were attachments to the FuGe 25A and were known as the FuGe 139. This apparatus was in development at Rechlin under the
supervision of Stabs.Ing. von HAUTEVILLE.
114. With this arrangement pulse modulations could not be read by the Allies, and for spoof purposes in order to produce a wrong indication we would have had to know the exact type of modulation accepted by it. Visual indication was also quicker and did not depend on knowledge
of morse.
115. This scheme was only in a very early stage of development and P/W were unable to give details. It was hoped that in due course it would be possible to develop matters a stage further and find a means of transmitting scrambled speech instead of morse, but P/W understood that
the question of pulse modulation for speech transmission had not been solved.

116. Consideration had been given in 1945 to the introduction of a crude system of navigation which could be only used within the boundaries of the Reich. This was to go under the code name of Rübezahl, and the fact that it was seriously considered and actively supported by the P/W responsible for Navigational Aids on the G.A.F. signals staff is an interesting reflection of the depths to which a combination of Allied jamming under-trained fighter had forced German technique.
117. It was expected that in the course of the summer of 1945 thousands of 162 Volksjäger would be available for the protection of the Fatherland. They were to be equipped with FuGe 24, which was to become the standard G.A.F. R/T set as described in A.D.I.(K) 343/1945. This set did not for the present give Benito control facilities and indeed as they were
short-range, high speed, fair-weather aircraft it was not certain that Benito control would be essentially needed.
118. It was essential that their relatively inexperienced pilots should have a simple means by which they could locate their approximate position without any additional navigation equipment having either to be manufactured or carried in the aircraft. It was therefore decided
to develop a system which could be used with FuGe 24.
119. In order to direct the Volksjäger pilots to their target, recourse was to be had to the night fighter system of broadcasting a commentary, and this commentary was to be combined with the primitive navigation system Rübezahl.
120. It was therefore planned to set up ground transmitters over Germany at 30 km intervals. The transmitters were to be beamed upwards, so that at 6,000 meters the polar diagram was about 40 km in diameter and lobes from neighbouring transmitters just overlapped, thus covering the whole area. Each transmitter emitted a plain language recognition signal in the
form of the name of its district, e.g. Halle, Magdeburg, etc.
121. All transmitters were to be operated on the same frequency so that to locate himself the pilot merely tuned his FuGe 24 to the frequency for the day. The ground transmitters were to be adapted from the FuGe 15 transmitters which had been manufactured in quantity as described
in paras. 23-39 of A.D.I.(K) 343/1945 before it was found that the FuGe 15 was unsuitable as an airborne R/T set. They were renamed Bs.15 (Bodensender).
122. Later it was believed that the night fighters which were also to carry FuGe 24 (see appendix 1) would also use the Rübezahl commentary as yet another alternative source for vectoring themselves to the bomber stream.

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German traffic analysis of russian communications


Lt. Werner RASCH, of the 353rd German Air Force Signal
Intelligence Regiment in the East, gives the folloving account
ot the development and achievements of the Russian Long Range
Bomber Forces (ADD--Avitsiya Dalneye Dyestviya).

"Soon after the outbreak of the Russian-German .
war, practically allot the Russian Long Range Bomber
Porce was destroyed, either by German attacks on
Russian airfields, or in combat with Geman fighters.
What was lett of it was withdrawn from action. Marshall
GOLOVANOV, chief of ADD, reorganized his forces
with the intention of using them in night opera~ions
only, owing to the threat presented by the strong
German flak defense. The first successful operations
following the reorganization took place in the battle
of Stalingrad (September 1942 - February 1943).
From then on, ADD operations played an important part
in all Russian ottens1ves. The training for night
operations was of long duration; at the end of'the
war each bomber reg1ment had crews which were still in
a training status. .
"The achievements of' the ADD units were not -
very impressive. Crews were not trained tor carrying
out night attacks in close formation. In the
latter days of the war 60 aircraft of a division
need approximately one hour to assemble and take
off, and even this was accomplished only- under the
most favourable navigational and meteorological
conditions. In planning an attack, each division
was allotted 20 minutes over the target; in that
time it was intended that all aircraft or one division
should have completed their mission and moved out to
make room for the next division. Unless targets on
the front itself were being raided, the front line
was usually crossed before dark. This permitted the take-off
to be made during daylight, and the first aircraft
to take of were held in an assembly area in order
that a close-flying formation be formed. Formations
equipped with radio-telephone communications were
again brought into close order by the leading
aircraft of the regiments before going into the
bomb run. Each regiment had several Pathfinder aircraft,
which were flown by the most experienced crews.
Since the success of the mission depended upon the1r
efforts. In addition to theflares, they usually
carried a 1,,000 pound bomb.
Point-to-Point Nets. --These po1nt-to-point nets of the
Long Range Bomber Forces (ADD) alone were a sufficient basis
on Which the Germans could build up an accurate picture ot
the ADD organization. When the 18th Russian Air Army was
reorganized the Germans immediately recognized such steps
from traffic on these nets. The most profitable traffic in these nets from an intelligence standpoint, came from units which were widely separated in the field as this necessitated the use of radio facilities for communication. In instances where the units were close together very little s1gnal
intelligence could be gained since there was slight need tor
radio transmissions.
From the intercept and analysis of traffic on these
point-to-point nets movements ot the Russian Air Army units,
locations and occupations of airfields numbers of operational
and unoperational aircraft and locations of supply dumps
could be determined. Traffic intercepted-on these nets
also gave the Germans considerable information regarding
intended operations and offensives. One outstanding success
along this line occurred when a Russian order to bomber units
was intercepted by the Germans. The message ordered an
attack on Shavli, Lithuania, where an entire German Panzer
Army was immobilized due to a lack of sufficient fuel.
The German Signal Intelligence Service reported the information to
the Lufttlotte which provided fighters to meet the Russian Long Range Bombers while German JU 52' s dropped gasoline supplies to the encircled Panzer Army and enabled it to escape.

Call Signs and Frequencies. --Three-character call signs were used in the radio nets between the Air Army and Air Corps. They were changed once during the day and once at night, at which time the frequencies also were changed.
I. Call signs were based on an arbitrary combination of letters and digits and were selected from a call sign list that changed monthly. The Germans were unable to determine whether any definite system was employed for the choosing of the call signs. They did notice however that during the course of a month a call sign used by a given radio station might be repeated without the succession of call signs which had followed at the time of the previous occurrence. Traffic between corps and divisions took place with a periodic change of call signs, but on fixed trequenc1es. This fact aided the intercept tasks of the German Signal Intelligence."

"a. Supply Traffic. --Valuable intelligence was obtained
by the German Signal Intelligence from the interception of [RUSSIAN] radlo traffic which gave details on supplies of fuel, ammunition and other materials. Details of railway movements of
supplies were transmitted by the District Air Base Depots to
thier subordinate airfield battalions. These messages contained information on the destination, number or railway cars being used, amount and type of supplies, and the scheduled time of arrival. When the trains arrived at their destination a message announcing their arrival was sent to the airfield battalions. As a result ot the exploitation of this type of traffic the Germans were able to bomb successfully the stations soon after trainloads or fuel and ammunition had arrived. In the Southern sector a service Command point-to-point radio net reported arrivals of replacement
aircraft tor the 17th, 5th, and 8th Air Armies. These replacement
planes were ferried from the factories to the airfields. Tactical'. units down to regimental level receipted for these planes and supplies, and from interception of these strength reports the Germans were able to estimate the production and distribution rate of Russian planes.
Current fuel and ammunition supplies at airfields were reported on pre-arranged message forms transmitted by the air-field battalions. These messages, since fuel and ammunition supplies were always increased prior to an offensive, afforded the Germans a sund basis for predicting impending Russian offensives.
b. Miscellaneous Air Service Command Traffic. --The
Russian Air Service Command reported by radio on the achievements in salvaging German aircraft which had been shot down or which had been forced to land. These reports afforded
the Germans with a source of informat1on concerning their missing crews, and in many, cases it was possible for the Germans to inform families that the crew members were alive and were Russian prisoners of war. Reports of interrogation of captured German military personnel were also often transmitted and intercepted by the Germans. In some cases as a result of the information contained in these reports, the German Command carried out court martial proceedings in absentia where the intercepted information carried sufficient proof that the German prisoners of war had revealed information of a secret nature. An Air service Command of
the 8th Russian Air Army on the southern front reported routes
to be flown by aircraft in large-scale ground attacks, giving
the time at which the attack would take place. For such attacks the Russian Air Army usually ordered the placing of smoke markers in the frontal area on the day before the attack would take place. These smokemarkers were used by the Russian planes as an orientation point, and not only indicated the proposed direction to be flown, but also corresponded to the direction the ground force would advance. After a study of these smoke signals the German Air Force Slgnial Intelligence learned that the signals were lit
thirty minutes to an hour before the actual time of attack.
Thus, when it was learned that smoke signals had been set
out the German Signal Intelligence could usually inform the Air and Ground forces some twenty-four hours in advance of plans tor a Russian offensive."
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Old 6th November 2018, 20:41
Allan125 Allan125 is offline
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Re: Researching the Luftwaffe through Prisoner Interrogations

Thanks Bruce, these continue to be fascinating reading, nice to see the other side of the hill, so to speak. Getting Court Martial proceedings against you in absentia, not good, hope nothing happened to the relevant families.


Allan Hillman
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Old 7th November 2018, 12:03
Bruce Dennis Bruce Dennis is offline
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Extracts of translation from report of Lt. LUDWIG of Chi. Stelle O.B.d.L

(note: TICOM report is dated post-war but no date is given for original report from LUDWIG.)
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