[aprssig] Doppler DFing

[scott at opentrac.org]

Someone at DCC gave me a paper with information on a particular Doppler
direction finding system, but I've misplaced it now - if you're that person,
please send me an email!

If there's ANY Doppler system with a serial output that you'd like to see
supported by the Tracker2, let me know - I need details on the data format,
and ideally plenty of sample data for testing.  I've got the Peet Bros
weather format working, and it's time to add some more parsers.  Autobaud is
working, too - no need to tell the tracker what port or baud rate to use,
just plug the GPS receiver into one port and the weather station into the
other, and it'll sort it out.  Hopefully I can make the DF support equally
simple.

Scott
N1VG