[digitalradio] Re: Contestia
On Sat, 17 Apr 2010 10:37:31 -0700, Brian Lloyd said: (I forgot to reply to all.) (I removed one level of characters below) On Sat, Apr 17, 2010 at 9:49 AM, Brian Lloyd wrote: [snip] It is really Really *REALLY* important to understand what is going on with these protocols in the presence of propagation anomalies in order to be able to make decisions about which modes work best under what conditions. My own recent experiments in monitoring and graphing the phase/frequency changes of the WWV carrier over time (20-30 minute samples typically) have convinced me that sequential testing of protocols, i.e. transmitting a message and then immediately transmitting the same message using the other protocol, is not likely to produce valid results unless repeated numerous times and then the results averaged with outliers discarded. True, and I seriously doubt that anyone has bothered to do that. The pskmail client - server communication does this all the time. It looks at the result of the last frames (both S/N and arq result) and decides on the mode to use for the next frame (separately for client and server mode). That way we always use the most effective mode for the circumstances. We don't need modes wider than 500 Hz to be fast, and change between raw PSK, robust PSK, MFSK and THOR modes. This way we are gathering lots of information on this subject automatically :) The contestia and olivia modes do not transmit the right character set so we cannot use them. 73, Rein PA0R
Re: [digitalradio] Re: Contestia
On Sun, 18 Apr 2010 09:06:46 +0200 (CEST), Rein Couperus r...@couperus.com said: On Sat, 17 Apr 2010 21:43:54 +0100, Stelios Bounanos said: On Sat, 17 Apr 2010 10:37:31 -0700, Brian Lloyd said: (I forgot to reply to all.) (I removed one level of characters below) It is really Really *REALLY* important to understand what is going on with these protocols in the presence of propagation anomalies in order to be able to make decisions about which modes work best under what conditions. My own recent experiments in monitoring and graphing the phase/frequency changes of the WWV carrier over time (20-30 minute samples typically) have convinced me that sequential testing of protocols, i.e. transmitting a message and then immediately transmitting the same message using the other protocol, is not likely to produce valid results unless repeated numerous times and then the results averaged with outliers discarded. True, and I seriously doubt that anyone has bothered to do that. The pskmail client - server communication does this all the time. It looks at the result of the last frames (both S/N and arq result) and decides on the mode to use for the next frame (separately for client and server mode). That way we always use the most effective mode for the circumstances. We don't need modes wider than 500 Hz to be fast, and change between raw PSK, robust PSK, MFSK and THOR modes. This way we are gathering lots of information on this subject automatically :) The contestia and olivia modes do not transmit the right character set so we cannot use them. I fixed up the quoted text above so it's clearer to see who was writing what. This thread was posted to the fldigi-alpha mailing list and can be read here (start with first Contestia email): http://www.mail-archive.com/fldigi-al...@lists.berlios.de/index.html http://lists.berlios.de/pipermail/fldigi-alpha/2010-April/thread.html#1099 Brian was saying that non-repeated, non-averaged tests are likely to be flawed. I said I doubted that anyone tested the right way (I still do :), since on-air test reports do not mention this stuff at all. At best, the testing is said to have been done over a period of time deemed long enough, but no graphs, no averaging, no apparent effort to discard invalid data. I know you've said that pskmail collects data to decide which modes to use. But other than switching modes, and perhaps logging that data locally, it's not telling anyone anything :-) If it could collect the S/N, loss % etc. for a period of time and set of modes, and make it available, that could be very interesting! Pskmail servers might export such statistics (even to non-participants) over HTTP. 73, Rein PA0R -- 73, Stelios, M0GLD.
Re: [digitalradio] Re: Contestia
I know you've said that pskmail collects data to decide which modes to use. But other than switching modes, and perhaps logging that data locally, it's not telling anyone anything :-) If it could collect the S/N, loss % etc. for a period of time and set of modes, and make it available, that could be very interesting! Pskmail servers might export such statistics (even to non-participants) over HTTP. Not a bad idea, I will see what I can do. Rein
[digitalradio] Digital signals via the Flex 5000A
All, I thought it might interest the group to see what digital looks like through the eyes of the Flex 5000A software defined radio. I tried to illustrate the point-and-click tuning of the Power SDR software as well as it's close-in filtering capabilities. Hope that comes across well. http://www34.zippyshare.com/v/31316642/file.html File size is 30MB and you will need the 7-zip utility to extract it -- 7 Zip seems shrink avi files to a much smaller size than other zip utilities. 7 Zip -- http://www.7-zip.org/download.html The video is best when viewed in full screen. Tony -K2MO PS: The Flex 5K works with all sound card software.
