Hi Glen, Yes cohpsk_ch could be used to apply amplitude variations. Replaying a chunk of your stored samples that demonstrates the issue is also a good approach.
You can also run the Octave version of the 700D demod, which will give a better view of the modems internal states. You won't be able to measure BER, but you'll be able to see if the LDPC decoder is converging, and if the demod is falling over in the fast ALC condition. - David On 14/7/20 5:09 pm, glen english wrote: > OK, in addition to my actual recordings, > > that would be using : > > https://github.com/drowe67/codec2/blob/master/src/cohpsk_ch.c > > together with > > https://github.com/drowe67/codec2/blob/master/octave/cohpsk_ch_fading.m > > ? > > On 7/14/2020 5:23 PM, David Rowe wrote: >> Hi Glen, >> >>> /* update mean amplitude estimate for LDPC decoder scaling */ >>> >>> ofdm->mean_amp = 0.9f * ofdm->mean_amp + 0.1f * sum_amp / >>> (ofdm->rowsperframe * ofdm->nc); >> Yes, that's used for LDPC decoding so could be related. >> >> It would also be useful to have a repeatable unit test to explore the >> issue, e.g. a repeatable fading profile running with the command line >> version of the modem. >> >> Cheers, >> David >> >> >> >> >> _______________________________________________ >> Freetel-codec2 mailing list >> Freetel-codec2@lists.sourceforge.net >> https://lists.sourceforge.net/lists/listinfo/freetel-codec2 > _______________________________________________ Freetel-codec2 mailing list Freetel-codec2@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/freetel-codec2
