This commit implements a new approach for the BPSK AX.25 decoding. It
seems that the GNU Radio equalizers (both CMA and LMS) are not ideal for
bursty transmissions. After they loose 'lock', they tend to converge
quite slow again.
The equalizing problem is again solved using an AGC2 block. However, the
placement of this block is quite critical. In older versions the AGC was
placed several steps after resampling and filtering. This resulted to
poor equalization and noise increase. Now the AGC is placed as early as
possible when the signal has a large span.
The new BPSK decoder uses a blind equalizer in par with an LMS based
equalizer. Both of them adapt more quickly in the channel response than
the AGC.
The decoder supports baudrates up to 19200.
Note that the bpsk_ax25.grc deprecates the bpsk_decoder.grc and
bpsk_demod.grc and they will be removed on the next release.
Manolis Surligas