Nice work Joel and Mark .... good to see some Codec 2 bits floating around my home town of Adelaide :-)
So this means you put OFDM modulation over FM? I guess that would work OK if FM preserves the modem tones OK and the SNR is high. I have been working on some link budget calculations which indicate that Codec 2 @ 1200 bit/s with a 1% BER requires a SNR of around 1dB (measured in a 2400Hz SSB bandwidth). This indicates it will sound significantly better than SSB for the same tx power and channel, although it's hard to make a direct comparison. Cheers, David On Fri, 2012-02-17 at 00:46 +1030, Joel Stanley wrote: > Hi Andreas, > > On Fri, Feb 17, 2012 at 00:10, Andreas Weller <[email protected]> > wrote: > > The start c2demo in the second terminal with: aoss ./c2demo > > Nice trick. I independently discovered a similar work around. > > Apply this hack to the sources of lc2poc: > > --- a/lc2poc/lc2poc.cpp > +++ b/lc2poc/lc2poc.cpp > @@ -142,10 +142,14 @@ static void populate_choice(Fl_Choice *c) > { > DIR *dirp; > struct dirent *dp; > char caption[64]; > > c->clear(); > > + c->add("/dev/dsp", 0, NULL, 0, 0); > + > + return; > + > dirp = opendir("/dev"); > > while (dirp) > > This should eliminate the need to create the /dev/dsp code. Then run > it using using the padsp wrapper from pulseaudio; I presume it > performs a similar LD_PRELOAD trick as aoss. > > $ padsp ./c2demo > > Mark and I managed to test Codec2 over the air tonight, transmitting > the pre-recorded samples on 70cm via a FM repeater where I decoded > them using a scanner and my laptop. In each case I only heard the > first half or so of the sentence, but it was quite clear. We have a > video of it in action that I'll put online tomorrow. > > Cheers, > > Joel > > ------------------------------------------------------------------------------ > Virtualization & Cloud Management Using Capacity Planning > Cloud computing makes use of virtualization - but cloud computing > also focuses on allowing computing to be delivered as a service. > http://www.accelacomm.com/jaw/sfnl/114/51521223/ > _______________________________________________ > Freetel-codec2 mailing list > [email protected] > https://lists.sourceforge.net/lists/listinfo/freetel-codec2 ------------------------------------------------------------------------------ Virtualization & Cloud Management Using Capacity Planning Cloud computing makes use of virtualization - but cloud computing also focuses on allowing computing to be delivered as a service. http://www.accelacomm.com/jaw/sfnl/114/51521223/ _______________________________________________ Freetel-codec2 mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/freetel-codec2
