Hello Tony, >What software are you using to determine the SNR decode level? What i do is adding noise so as to reach a S/N=-15 dB. Then I see if it works (decode or not). According to the result, I will try -14 or -16 dB etc...
In Multipsk when it is possible I evaluate the S/N by measuring the signal energy in its band and noise in the reminder of the band (or part of it). After normalization to a 3 KHz noise bandwidth, I display the result (which is not very precise). There are other methods (based on correlations and hypothesis) as with Olivia and JT65 but they are neither very precise. For example, you could evaluate the S/N according to the phase jitter in PSK mode (the more the phase moves randomly, the lower the S/N ratio is), but this would work only in good ionospheric conditions. 73 Patrick ----- Original Message ----- From: Tony To: digitalradio@yahoogroups.com Sent: Sunday, November 01, 2009 12:44 AM Subject: Re: [digitalradio] Message ID in multipsk Patrick, I think you are right about the burst characteristics of the mode and the way the PathSim software handles this. Seems logical since our SNR tests have been consistent with other modes. I have an audio editor that has the capability of adding white noise, but it doesn't indicate the SNR once the mode audio is mixed. > I mix signal and noise at digital level before the analogical transform and then I see at what level I can > decode. What software are you using to determine the SNR decode level? Tony -K2MO >
