[Tango Echo Dog]

Alex
The French Air Force had numerous problems; fragmented command, poor pre-war training which emphasised daylight/fair-weather operations (but then so did the RAF) and a failure to achieve maximum effort, especially the fighter units which rarely seemed to average more than one or two sorties per pilot per day.
The French certainly used a great deal of comint and appear to have had their own Ultra system for they (and the British) had lots of notice of Unternehmen 'P' (Paula). They were helped by poor Luftwaffe signals security in which an Enigma signal clearly stating that Object P was Paris was sent to one Kampfgeschwader. The French also had a form of airborne early warning with Potez 631s tracking enemy bomber formations targeting Paris and providing a running commentry. The British had extended their RDF system into northern France and had begun handing over stations and sets to the French during the spring.
If you really want to know about the French Air Force go to the Chateau de Vincennes and the air force archives. Even if you speak poor French you can get by and the staff are very helpful.
I agree about Invisibles Vainquers and there is a useful background book 'The Forgotten Air Force: French air doctrine in the 1930s' by Anthony Christopher Cain. Smithsonian Institution Press, Washington/London, 2002 ISBN 1-58834-010-4 which you might be able to order through your local library. There is a book shop specialising in aviation in Paris with loads of French language books but I have forgotten the name and address. I am sure other members will be able to help you.
Tango Echo Dog