fsk_find_frame() takes expect_bits_string (e.g. "10dddddddd1"), as a
parameter supplied by the caller allowing for encodings which don't use
any start/stop bits (e.g. just "dddddddd").
Computes SNR confidence value, where "signal" is the magnitude of the FSK
driven frequency, and "noise" is the magnitude of the non-driven frequency.
(Also includes unused algo #4 code, which may not compile anymore.)
Kamal Mostafa