I'm not sure why 48 kHz was used, other than it makes for a more pure waveform, and is compatible with sound cards. You need at least 9600 Hz, as the 4800 Hz tone would need as a minimum 2X to get it sampled. I suspect 16 kHz would work good in firmware A/D or D/A (without a sound card).
The main concept is the tone spacing is at the symbol rate, and that's what gives it the high performance. I wonder if you changed the first tone to 400 Hz as then you would have 1600, 2800, and 4000 tones, and then 8 kHz would sample it correctly. Just an idea. If you are using FM then, you want to move the baseband left anyway, as the FM modulation bandwidth is probably about 16 kHz. On Wed, Oct 23, 2019 at 2:28 PM Adrian Musceac <kanto...@gmail.com> wrote: > > So does this mean the input sample rate is also 48 kHz? That would make it > harder for me because all the other modes use 8 kHz... > > On October 23, 2019 4:20:48 PM UTC, Steve <coupaydevi...@gmail.com> wrote: >> >> On Wed, Oct 23, 2019 at 10:44 AM Adrian Musceac <kanto...@gmail.com> wrote: >>> >>> >>> Regarding mode 2400A, can someone confirm that the output of this mode is >>> resampled to 48 kHz? >>> I'm trying to add it, but some numbers don't work for me. >> >> >> It's not resampled, it is generated at 48 kHz rather than 8 kHz as in >> other modes. >> Due to the tones being 1200,2400,3600,4800 Hz. >> ________________________________ >> 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 _______________________________________________ Freetel-codec2 mailing list Freetel-codec2@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/freetel-codec2
