Hello Tony, The S/N that you measure seems quite close to mine (-20 dB against -16 dB and -14 against -13 dB). In our measures, there is always a certain uncertainty because the noise is not really white after going through a sound card output and a sound card input. Moreover, in fact in all my tests, I accept about 2 % of errors because 0% error is impossible to reach (it can be approched but not reached). So there is certainly a small uncertainty about the 100% success. I think the 4 dB in RS ID of difference must due to the "burst" character of the RS ID as Path Sim introduces filters having a certain length, so...
>If it's ok with you, I'll send a few audio clips so you can test the RSID and >Call ID at different SNR levels measured with PathSim. I'll >include the SNR >in the clip title. Thanks Tony, but I'm more confident on what I program. >the Multipsk S/N indicator to measure the signal-to-noise The Call ID S/N is not precise at all. It can only give an idea of the S/N value. 73 Patrick ----- Original Message ----- From: Tony To: digitalradio@yahoogroups.com Sent: Saturday, October 31, 2009 3:05 AM Subject: Re: [digitalradio] Message ID in multipsk Patrick, > Hello Tony, What are the numbers that you get? In fact, from my measures, the first > decodings appear at -19 dB in RS ID and -16 dB in Call ID (but respectively -16 and -13 dB > for almost 100 % success). I get the following SNR figures for 100% decode: RS ID -20db Call ID -14db Figures are nearly the same for the Call ID, but the 4db discrepancy in the RSID seems odd. I believe this is the first time we've compared SNR figures for 100% throughput Patrick; our minimum SNR figures are usually identical. > I think it must be a bit difficult to measure S/N for bursts. I mix signal and noise (just noise without paths delays...) at digital level before the analogical transform and then I see at what level I can decode. Sounds like an accurate way to test Patrick. Most of my digital mode testing is done with PathSim. The program gives the option of testing the signal-to-noise ratio using Gaussian white noise without any ionospheric path distortion. I'm always careful to make sure that the audio levels are the same for each mode before I run them through the simulator. If it's ok with you, I'll send a few audio clips so you can test the RSID and Call ID at different SNR levels measured with PathSim. I'll include the SNR in the clip title. Thanks Patrick, Tony -K2MO > > ----- Original Message ----- > From: Tony > To: digitalradio@yahoogroups.com > Sent: Friday, October 30, 2009 2:09 AM > Subject: Re: [digitalradio] Message ID in multipsk > > > > > > Patrick, > > Thanks for adding the messaging feature. Andy, K3UK, and I were able to copy Sholto's, RS messages some 3700km away on 20 meters. Sholto, K7TMG, was running 5 watts and a vertical antenna. We found the high sensitivity of the message mode useful as signals fell below the decode threshold of the chat modes we were using at the time. > > > The RS ID is detectable at -16 dB but the Call ID only at about -13 dB (however still better > > than PSK31). > > Very sensitive, more than most sound card chat-modes. I'm not sure why Patrick, but my SNR tests indicate that the RSID used for mode detection has a 6db advantage over the CALL ID. I ran both modes through the path simulator 10 times each and established a minimum SNR when they decoded 10 out-of 10 times or 100%. > > I'll check all levels and try again. > > Thanks Patrick. > > Tony -K2MO > > > > > > > ----- Original Message ----- > From: "Patrick Lindecker" <f6...@free.fr> > To: <digitalradio@yahoogroups.com> > Sent: Thursday, October 29, 2009 4:38 PM > Subject: Re: [digitalradio] Message ID in multipsk > > > > Hello Tony, > > > > The Call ID that I just have slightly modified is based on a specific RS ID code (it was the most simple, but it is not a mode ID, just a borrowing) on which is implemented a more conventional frame (56 bits + CRC). The RS ID is detectable at -16 dB but the Call ID only at about -13 dB (however still better than PSK31). > > > > 73 > > Patrick > > > > ----- Original Message ----- > > From: Tony > > To: digitalradio@yahoogroups.com > > Sent: Thursday, October 29, 2009 7:52 PM > > Subject: Re: [digitalradio] Message ID in multipsk > > > > > > > > > > > > Steinar, > > > > > I am testing the " Message ID" in Patrick's latest beta of the > > > MULTIPSK (VERSION 4.16 of 27/10/2009) on 14.074. > > > > I haven't had the opportunity to use the message ID on-the-air, but I did test the mode between two PC's and it seems to work fine. > > > > I would assume the Reed Solomon messaging will be just as sensitive and robust as RS ID; should work well. Hope to see you on the air Steinar... > > > > Tony -K2MO > > > > > > > > > > > > > > > >
