MalcolmRobb/dump1090 — pull request #57 by kad (2014-11-02 16:00:35+00:00)
Title: Fully validate ModeS preamble before trying ModeA

ModeA messages are shorter than ModeS and thus
sometimes broken ModeS messages are detected as
bogus ModeA messages.
To eliminate that, I think it would better idea to see if preamble is actually
ModeS, even broken one, and only then try to see if it would match as ModeA.