Luftwaffe data from ULTRA

[RodM]

Hello One & All,

I recently bit the bullet and have started to go through the ULTRA decrypts in the DEFE 3 series from the PRO.

For the record, being in New Zealand, this has meant ordering duplicates of the relevent microfilms. As a sampler, I obtained DEFE 3/517-518, which covers 15th-20th March 1945 (6 days) at a cost of GBP55 plus postage. It took just under a month from payment to receive the duplicate and the British National Archives website and ordering system is first class. Obviously, obtaining duplicates for a wider time frame will be very expensive (but, still cheaper than hiring a researcher to combe through the material).

Allied with further material at the PRO on Luftwaffe W/T radio traffic, it has been possible to build up a good picture of operations (specifically, Nachtjagd operations Jan-Apr 1945).

Anyway, for those with vastly more experience of this material, I do have a couple of questions:

1. A straight abbreviation of "ARC" is often used. Does anyone know what it means?

2. Keywords are often repeated (i.e. "Rheine & Rheine"). Does any know the reason for this other than to add clarity.

3. From what I have seen, it appears that the decrypts are not reproduced verbatim (in decoded form). Therefore, I get the impression that some information may have been left out at the discretion of the intelligence staff. Is this a fair assumption and, out of interest, do the original (full) decrypts still exist?

Cheers

RodM

[SES]

Hi RodM,
I cannot answer any of your questions, but this may ad to solving some of the puzzle:
Names and callsigns for Luftwaffe JK and JD control centers (Gefechtsstände):
http://www.gyges.dk/Luftwaffe%20comm...facilities.htm
you will see some blanks. I would be grateful if you, based on your material, could help fill these.

Operational brevity code used for radio traffic by Luftwaffe nightfighters and control centers:
http://www.gyges.dk/Operational%20brevity%20code.htm

Command and control arrangement for II JK spring 1945:
http://www.gyges.dk/II%20JK%20spring%201945.htm

bregds
SES
www.gyges.dk

[ju55dk]

1. ARC=airfield regionel command/Flughafenbereich.
2. It is for clarity. This method is still in use in radiocommunication today!
3. Yes they are not translated directly, but nothing important was left out, as these were used by those "who needs to know", and who had to make decisions based on what was picked up by Ultra!!

Junker

[Nick Beale]

I've been using Ultra since about 1990 (unlike you I'm only 300 km from London). Like you say, there's rather a lot of material...

ARC isn't the only abbreviation you'll find. Another is "Able Oboe" = AO = Air Officer in Command = Kommandierender General. "Nan Sugar" for Nachtschlachtgruppe, "Jig Dog" for Jagddivision and so on.



Signals weren't verbatim translations of the original, they are described as "reports to Allied commands". Partly this is for security - if the enemy suspects you have re-broadcast his exact message, it gives him a possible break into your own code. Some Ultras have lines from popular songs inserted into the text for added security.



Also, German code names were substituted by British ones. You need to find the message with the fist mention to find out what the German name was. "Einhorn" became "Salter" for instance.



Another reason was that the originals would be unintelligible to anyone but an expert. The originals are supposed to have been burned in 1946 (see the Channel 4 documentary "Station X" if you can get the video).

BUT in series HW1 are files with a daily selection of Ultras (maybe 4 or 5 a day) that were brought to Churchill's attention. These contain the verbatim translation and the signal as issued to Allied commands. You quickly find that there were codes within codes: GAMOZ and GEKOZ were Luftwaffe command echelons (I forget which) for instance.
Finally: I'd recommend "Enigma" by Sebastian Sebag-Montefiore. It's mostly about naval Ultra but it does explain a lot about how the system worked.

[RodM]

Thank you SES, Junker and Nick for your replies.


Firstly, SES, the reports that I have so far looked at in detail for night-to-night information on Nachtjagd operations don't really give any information on the ground control structure in use. Mention is made of beacons used and the number and type of transmissions jammed. The rest of the information concerns the movement in the air of night fighters and how the controllers reacted to the raids (ref: Air Ministry W/T Intelligence Service Daily Summaries (AIR 22/503) / Bomber Command: Signals Intelligence & RCM Reports (AIR 40/2370) / Bomber Command Interception Tactics Reports (AIR 14/3745)).

I do have an Operational Research Section Report - "Benito" and "Egon" German route tracking and R.C.M (AIR 20/1654) - it reports on German efforts to gain better tactical information from signals intelligence and efforts at jamming Oboe. Having seen your site, I don't believe the report has anything to add as, it should be remembered, the Air Ministry intelligence service was really making educated "guesses", sometimes with limited information. For example, one theory in the report concerns Luftwaffe efforts to deduce the path of the bomber stream by analysing the patterns of the high and low Mosquito intruders. I will provide some specific detail from the report in a further post below...

There are other potentially interesting reports at the PRO but I haven't got around to ordering them yet.

Junker and Nick, thank you for your explanations.

One reason why the "ARC" abbreviation stood out was because, in the 25 Nachtjagd messages extracted from the six-day period concerned, it was the only abbreviation NOT given in the phonetic alphabet.

I must say that the ULTRA material is a perfect example of a "follow the bread crumbs" senario, especially with one signal leading to reference to another signal - I can see the "hunt" becoming very addictive (and expensive!)...

Cheers

Rod

[SES]

Originally Posted by RodM

Thank you SES, Junker and Nick for your replies.


Firstly, SES, the reports that I have so far looked at in detail for night-to-night information on Nachtjagd operations don't really give any information on the ground control structure in use. Mention is made of beacons used and the number and type of transmissions jammed. The rest of the information concerns the movement in the air of night fighters and how the controllers reacted to the raids (ref: Air Ministry W/T Intelligence Service Daily Summaries (AIR 22/503) / Bomber Command: Signals Intelligence & RCM Reports (AIR 40/2370) / Bomber Command Interception Tactics Reports (AIR 14/3745)).


Cheers

Rod

Hi Rod,
Glad we got in touch. Are controller callsigns specifically mentioned or do they use "the controller at such and such a division"?

bregds
SES

[RodM]

For SES, extracts from Air Ministry Report:


Air Scientific Intelligence - Report No. 83 - Recent Developments in German Route Tracking and RCM (dated 26.3.45)

Since report No. 73 (July 1944) new developments highlighted -

1. formation of specialist RCM unit
2. spread of route tracking to GCI stations
3. use of listening recivers for guiding long-range radars

It notes that the function of the RCM unit is largely deployed in the problem of jamming Oboe.

1. RCM Development - History

Nov 1943, special detachment of German Air Signals Experimental Regiment established near Duisburg for investigating methods of defence against Oboe. The unit was able to cover most Oboe transmissions in Germany from Duisburg.

During 1944, transmissions were plotted successfully by listening and Oboe Mk I was then successfully jammed. In May 1944 the unit was commended for it's work during a big attack on Duisburg.

The unit had managed to identify and plot Oboe Mk II transmissions and thusidentify the main raids from the spoofs - being the only unit which gave a clear picture of the Duisburg raid.

The techniques developed were then passed on to the whole route tracking organisation.

In the second half of 1944, a jammer against centimetic Oboe was introduced. The unit is began to develop counter-measures against other navigational aids.

2. Deployment

Very little info known (since the intelligence service had difficulty tracking movements via ULTRA because of a change in unit nomenclature by the Germans). Unit concerned was IVth Abteiltung of LN Regiment 351 with 25 to 30 stations in Western Germany. Most stations were deployed in the valley of the Rhine. With Allied advances, units were forced to withdraw and deployment (at date of report) not known. Units were mobile and it was assumed that because of fuel shortage, mobile generators were not an option so they would have to be positioned close to a electricity supply.

3. Listening

New procedure developed where unit claimed to be able to give "10-15 minutes" warning of target.

It turned out that new method was simply listening to W/T traffic between Oboe ground stations (presumedly on the continent), so Oboe procedure was tightened up and land lines used for communications more often.

4. Jamming

Method of jamming Oboe Mk I was relatively simple to achieve. Modified Freya used to interrogate the a/c set, wait unit the the a/c was close to the release point and then jam the signal.

Equipment used to jam centimetic Oboe was device called "Ali-Baba Gerat" - at least three versions produced to cover metric and centimetic Oboe. This device seen as centimetic jammer employing two methods to jam -

(1) straight interrogation
(2) Method known as "Ball" - Korfu D/F sets are used to try to lock in on the signal (cm Oboe transmissions narrower and more directional making it hard to stay focused on the transmission).

Thus two techiques comprise 1. above: unlocked pulses due to straight interrogation of the set and 2. above: locked pulses were the jammer is tracked using "Ball".

Only in late Feb/Mar 1945 did RAF BC No. 8 Grp and USAAF 8th AF notice increased jamming. RAF No. 60 Grp took ranges and bearings on locked pulses and found originating location was at a known jamming site (location of which not given in report).

Apparently the unit mainly works during the day, according to the report, presumedly because more jamming was encountered then.

5. Aids to Flak

Refers to map captured near Duisburg which basically showed technique whereby Oboe plotting data could be fed in to flak predictors.

The map showed the positions of Allied Oboe stations and thus, the Germans would have to guess which stations were being used at a given time for the technique to work, The report adds that two Oboe sites on the map were at locations were no Oboe station ever existed.

6. GEE

IV LN Reg 351 believed to be involved in tracking and jamming of GEE

7. GEE-H

In Oct 1944, captured equipment finally gave Germans clues about GEE-H system. Some Ali-Baba Gerats then converted to GEE-H frequency. It was thought that by then using "Ball" technique, it should have been possible to commence jamming of GEE-H transmissions but no effective jamming had been encountered to date.

8. SS LORAN

Germans started jamming SS Loran in Feb 1945 using noise modulation. One such jamming station identified was connected by land-line to nearest station of IV LN Regt 351.

9. Route-Tracking & GCI Stations

According to the report, the Germans had held the opinion for some time that analysing correctly the movements of the Mosquito night fighters, especially distinguishing between high and low patrols, would enable them to deduce the intentions of the main bomber force.

In Sep 1944 a special detachment of the German Air Signals Experimental Regiment was provided with "Naxburg" and told to investigate the 10cm AI signals from RAF night fighters. Work of this unit apparently successful as most GCI stations in Western Europe issued with Naxburg and Heinrich sets.

According to the report, the Heinrich sets could be used to D/F the 'Jostle' support aircraft in the bomber streams, carrying jammers on the 38-42 Mc/s band. Thus it was assumed that the GCI stations were taking part in the route tracking of the RAF night fighters and 'Jostle' aircraft, while the actual analysis was still performed in the plotting stations.

10. Use of Listening Receivers in Conjunction with Long Range Radar

In Nov 1944, a number of long-range radar sets (i.e. Wassermann, Mammut) in the coastal sectors were issued with Korfu 812 D/F sets. These were to be used to guide the radar sets onto the bombers and not for route tracking. It was thought that because RAF bombers were forbidden from using H2S until close to the German frontier, the sets were being used to guide the radar on to USAAF 8th AF Bombers during their assembly over the UK.

That's it in a nutshell

Cheers

Rod

[RodM]

Hi SES,


in answer to your question, the reports mentioned in my post do not go into such detail, only occasionally identifying controllers by Jagd Division.

It should be remembered that these reports are interpretations of the signals intelligence data and not the raw data itself.

I am expecting a load of No 80 Signals Wing reports any day now, although I have no reason to expect them to be any more specific.

Cheers

Rod

[SES]

Hi Rod,
Thank you, I can go endleslsy, when you or the forum get's fed-up please say so and we can go off-board.
I have some comments.
For SES, extracts from Air Ministry Report:


Air Scientific Intelligence - Report No. 83 - Recent Developments in German Route Tracking and RCM (dated 26.3.45)

Since report No. 73 (July 1944) new developments highlighted -

1. formation of specialist RCM unit
2. spread of route tracking to GCI stations
3. use of listening recivers for guiding long-range radars

It notes that the function of the RCM unit is largely deployed in the problem of jamming Oboe.

1. RCM Development - History

Nov 1943, special detachment of German Air Signals Experimental Regiment established near Duisburg for investigating methods of defence against Oboe. The unit was able to cover most Oboe transmissions in Germany from Duisburg.

During 1944, transmissions were plotted successfully by listening and Oboe Mk I was then successfully jammed. In May 1944 the unit was commended for it's work during a big attack on Duisburg.

The unit had managed to identify and plot Oboe Mk II transmissions and thusidentify the main raids from the spoofs - being the only unit which gave a clear picture of the Duisburg raid.

The techniques developed were then passed on to the whole route tracking organisation.

In the second half of 1944, a jammer against centimetic Oboe was introduced. The unit is began to develop counter-measures against other navigational aids.
Correct, please see:
http://www.gyges.dk/jamming_service%20Oboe.htm

2. Deployment

Very little info known (since the intelligence service had difficulty tracking movements via ULTRA because of a change in unit nomenclature by the Germans). Unit concerned was IVth Abteiltung of LN Regiment 351 with 25 to 30 stations in Western Germany. Most stations were deployed in the valley of the Rhine. With Allied advances, units were forced to withdraw and deployment (at date of report) not known. Units were mobile and it was assumed that because of fuel shortage, mobile generators were not an option so they would have to be positioned close to a electricity supply.
Incorrect. Some of these units were in the middle of nowhere.

3. Listening

New procedure developed where unit claimed to be able to give "10-15 minutes" warning of target.
Correct. The morse signals exchanged between the aircraft and the ground station gave a count down to bomb release starting 10 min out. At this point the target was also frequently identified and warned, often through The Ruhr Stab. The air raid warning was sounded and the facility evacuated.

It turned out that new method was simply listening to W/T traffic between Oboe ground stations (presumedly on the continent), so Oboe procedure was tightened up and land lines used for communications more often.
Didn't help. The germans exploited the Morse signals as described above.

4. Jamming

Method of jamming Oboe Mk I was relatively simple to achieve. Modified Freya used to interrogate the a/c set
Incorrect. The reciever was a modified Würzburg Dora called the Naxburg.

, wait unit the the a/c was close to the release point and then jam the signal.

Equipment used to jam centimetic Oboe was device called "Ali-Baba Gerat" -
The German SIGINT name for Oboe was Bumerang. The jammer was thus an Anti-Bumerang Gerät. So you have the A & B. If Ali-Baba was a German nick-name I don't know.

at least three versions produced to cover metric and centimetic Oboe. This device seen as centimetic jammer employing two methods to jam -
Correct, please see link above.

(1) straight interrogation
(2) Method known as "Ball" - Korfu D/F sets (Naxburg) are used to try to lock in on the signal (cm Oboe transmissions narrower and more directional making it hard to stay focused on the transmission).

Thus two techiques comprise 1. above: unlocked pulses due to straight interrogation of the set and 2. above: locked pulses were the jammer is tracked using "Ball".

Only in late Feb/Mar 1945 did RAF BC No. 8 Grp and USAAF 8th AF notice increased jamming. RAF No. 60 Grp took ranges and bearings on locked pulses and found originating location was at a known jamming site (location of which not given in report).

Apparently the unit mainly works during the day, according to the report, presumedly because more jamming was encountered then.

5. Aids to Flak

Refers to map captured near Duisburg which basically showed technique whereby Oboe plotting data could be fed in to flak predictors.
Correct.

The map showed the positions of Allied Oboe stations and thus, the Germans would have to guess which stations were being used at a given time for the technique to work,
Incorrect. It was the signal from the aircraft which was intercepted and exploited.

The report adds that two Oboe sites on the map were at locations were no Oboe station ever existed.

6. GEE

IV LN Reg 351 believed to be involved in tracking and jamming of GEE
Correct, please see:
http://www.gyges.dk/jamming_service%20GEE.htm
and this ocured earlier than jamming of Oboe.

7. GEE-H

In Oct 1944, captured equipment finally gave Germans clues about GEE-H system. Some Ali-Baba Gerats then converted to GEE-H frequency. It was thought that by then using "Ball" technique, it should have been possible to commence jamming of GEE-H transmissions but no effective jamming had been encountered to date.

8. SS LORAN

Germans started jamming SS Loran in Feb 1945 using noise modulation. One such jamming station identified was connected by land-line to nearest station of IV LN Regt 351.

9. Route-Tracking & GCI Stations

According to the report, the Germans had held the opinion for some time that analysing correctly the movements of the Mosquito night fighters, especially distinguishing between high and low patrols, would enable them to deduce the intentions of the main bomber force.

In Sep 1944 a special detachment of the German Air Signals Experimental Regiment was provided with "Naxburg" and told to investigate the 10cm AI signals from RAF night fighters.
Never heard of this, technically feasible using Naxburg.

Work of this unit apparently successful as most GCI stations in Western Europe issued with Naxburg and Heinrich sets.
Not correct. Cannot be confirmed in German sources and the Naxburg was produced in fairly small numbers. Heinrich is the name of the GEE jammmer and this was employed in special sites. It is also the D/F part of the Y-Linien (Benito) system. And all Himmelbett Stellungen was equipped with these systems.

According to the report, the Heinrich sets could be used to D/F the 'Jostle' support aircraft in the bomber streams, carrying jammers on the 38-42 Mc/s band. Thus it was assumed that the GCI stations were taking part in the route tracking of the RAF night fighters and 'Jostle' aircraft, while the actual analysis was still performed in the plotting stations.
Incorrect. The Heinrich-Peiler might be able to take bearings on the jamming, but neither the Flugmeldemess Stellungen, nor the Jägerleit Stellungen were affiliated with the Funkaufklärungs Dienst.

10. Use of Listening Receivers in Conjunction with Long Range Radar

In Nov 1944, a number of long-range radar sets (i.e. Wassermann, Mammut) in the coastal sectors were issued with Korfu 812 D/F sets.
New to me, but I know for fact that one Stellung in Denmark (RINGELNATTER) as the only one was equipped with a Korfu.

These were to be used to guide the radar sets onto the bombers and not for route tracking. It was thought that because RAF bombers were forbidden from using H2S
Slightly odd comment. The Pathfinders in the Bomber Stream used H2S to find and mark turning points, and it was this indiscrimite use of H2S, which enabled the Luftwaffe to track The Stream from very early on during the approach.

until close to the German frontier, the sets were being used to guide the radar on to USAAF 8th AF Bombers during their assembly over the UK.

That's it in a nutshell

Cheers

Rod

[Jan Bobek]

For instance I am not fed-up at all. I look at your discussion with great interest.

Would you please help me with guidance how to identify and order ULTRA files related to Luftwaffe?

thanks in advance for advice

Jan