Here is a good web site to identify digital signals
click on a suspected mode and it plays the audio thru your computer

http://www.wunclub.com/sounds/

And another one at URL:
http://www.kb9ukd.com/digital/


And another
http://rover.wiesbaden.netsurf.de/~s.../DIG_intro.htm

Have fun with the mind boggling sounds



--
CL -- I doubt, therefore I might be !