On Mon, Apr 6, 2020 at 11:29 PM Jeroen Vreeken <[email protected]> wrote: > I also found that in its current form it isn't very good at coding audio > received from an analog QSO... > For example this is a recording of our local net from this week: > http://dmlinking.net/audio/2020/04/pi4za.202004050900.wav
This signal has a significant amount of DC offset. I'm not sure if the lpcnet codec has a highpass filter. You might want to try high-passing it at 300Hz or so. On Wed, Apr 1, 2020 at 8:08 PM David Rowe <[email protected]> wrote: > The idea of a low MDS VHF/UHF stand alone radio embodying some of the > concepts of the SM2000 is still intriguing to me: > > + efficient modems and low noise figure, so it runs DV in the < -130dBm > range (20dB better than FM and 1st gen DV) > + LPCNet style wideband codec > + something stand alone/portable/HT form factor > + minimal hardware lockdown/high performance modem (avoid chipsets with > the modem inside) > + a few watts power output, proper PA filtering that meets commercial specs The classic arguments against SSB/etc support in small radios such as HTs was frequency stability which seems to be moot with modern tcxo (and mems oscillators) and linearity-- yet we seem to have cell phones using linearity sensitivity modulation now just fine. :) The lack of openness in most modern ham firmware is a real letdown, especially since the devices are increasingly highly agile SDRs from a hardware perspective. _______________________________________________ Freetel-codec2 mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/freetel-codec2
