Marcus, w/o AGC audio sometimes is creapy. I have tested AGC2, tried to play with attack and decay, but at last when there is a plane in the vicinity dongle overloads and sound become very loud. Then i tested FAGC and it fits well! 1024M/64 gives 16k and 256 samples equals - 62 ms of signal. Works ok for me.
On Fri, Apr 25, 2014 at 7:25 PM, Marcus Müller <[email protected]> wrote: > -----BEGIN PGP SIGNED MESSAGE----- > Hash: SHA1 > > Actually I'm a little confused - Is seeing an AGC in an AM demodulator > something you usually do? > Especially the feedforward AGC should be rather err jumpy with a scope > of but 256 samples, unless I'm missing something; f_sample seems to be > 1024ksps, thus 256 samples max search and rescaling should behave very > badly if there are baseband signal contents below 4kHz -- and that > should be the case for audio, usually? > > Greetings, > Marcus > > On 25.04.2014 16:03, Marcus Leech wrote: > > An AM demodulator is a squaring function. It can only *ever* > > produce positive values. You can remove DC offset by using a > > high-pass filter after it. on Apr 25, 2014, *Anton Komarov* > > <[email protected]> wrote: > > > > But when we have only positive values that means in fact we have > > 0.5 DC offset, and that is bad. Moreover i've made test recording > > with GQRX - waveform is fine! Looking into the code, nothing > > special, am demod->low-pass->wav-sink. > > > > -- public PGP key http://pastebin.com/dqZqgyVE > > > > > > On Fri, Apr 25, 2014 at 5:11 PM, Michael Ossmann <[email protected] > > <mailto:[email protected]>> wrote: > > > > On Fri, Apr 25, 2014 at 04:14:30PM +0400, Anton Komarov wrote: > >> > >> Hi, you can find in attach AM demodulator grc file. Everything > >> is straight forward with demod but audio file generated looks > >> weird. Only positive values of amplitude. > > The particular definition of "amplitude" adopted by GNU Radio (and > > pretty much everyone else in SDR as far as I know) is "absolute > > value". It is correct for it to always be positive. > > > > > > > -------------------------------------------------------------------------------- > > > > _______________________________________________ Discuss-gnuradio > > mailing list [email protected] > > <mailto:[email protected]> > > https://lists.gnu.org/mailman/listinfo/discuss-gnuradio > > > > > > > > _______________________________________________ Discuss-gnuradio > > mailing list [email protected] > > https://lists.gnu.org/mailman/listinfo/discuss-gnuradio > > > -----BEGIN PGP SIGNATURE----- > Version: GnuPG v1 > Comment: Using GnuPG with Thunderbird - http://www.enigmail.net/ > > iQEcBAEBAgAGBQJTWn5MAAoJEBQ6EdjyzlHtWSEIAKSNLkujZEL/lpmy/CBrK76+ > 144zh4QY9QkAd9jgYHE/lSp6oAP2EEIXI7xQw1AC+2c2c2+pcG92ydJs/2/pvEa3 > zfyVUtSr5e8qByokifDCq1HeMFG4q5Uis/cNgWlQPBeWR5My6ngnE3xC4TmMhGO6 > WCYFqyrf7dz+P/cXClRs9jIVv4HKPLCZky9qdmG/9rXFxovQt369boaXDdvtc6Ga > dnNswR2zXh63IH+ZWaARTiB61GJ/oPw/yh1jL9inVOFhioZstUFK0xS1ACxFZBiY > P1nHuixHkGXmIp6jp1QXo6H9QAqVZ5z/H4Tngd8EM+i+KsqxaJncvzGW7MVgaQA= > =XADd > -----END PGP SIGNATURE----- > > _______________________________________________ > Discuss-gnuradio mailing list > [email protected] > https://lists.gnu.org/mailman/listinfo/discuss-gnuradio >
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