Demonstrating a suite of digital coding methods are vulnerable to Doppler spread does not tell the whole story. What does the signal look like on the a spectrogram when subjected to Doppler spread? Yes, you have incomplete or scrambled text, but then the root cause of that could be anything.
It would be valuable to the community to be able to recognize the presence of Doppler spread by some visual or aural means. Armed with this information then one begins to make choices of other modes that would be less vulnerable to the effects of Doppler spread. philw de ka1gmn On Tue, Jan 5, 2010 at 2:13 AM, Tony <d...@optonline.net> wrote: > > > Phil, > > > What about PSKFEC31 under the same test scenarios? > > Have a look: > > Path Simulation: High Latitude (Moderate) > Path Delay: 3ms, Doppler spread 10Hz > Pangram Text: Quick Brown Fox > > > PSK31FEC > > t e tio E ttaeH loo etee- e e e ˆyaooe n o > ao t aeepvede n neete ueeeu .tna0 o een > it=pctidr a ieae t e tio E ttaeH loo etee- e e > etˆyaooe on oe ne 6etnuEenoel o·b geogtee > > > PSK63F > > the quick brown fox jumps over the lazy dog > the quick brown fox jumps over the lazy dog > the quick brown fox jumps over the lazy dog > > Tony -K2MO > > > > > ----- Original Message ----- > From: Phil Williams > To: digitalradio@yahoogroups.com > Sent: Monday, January 04, 2010 5:16 AM > Subject: Re: [digitalradio] IZ8BLY's PSK63F > > > > Very interesting. What about PSKFEC31 under the same test scenarios? > Certainly, there would be more a in throughput, but that is a matter of some > liberal use of CW shorthand. > > > philw de ka1gmn > > > On Mon, Jan 4, 2010 at 2:48 AM, Tony <d...@optonline.net> wrote: > > > All, > > Recent path simulation tests indicate that Nino Porcino's PSK63F offers > better performance over PSK31 and PSK63 in a couple of areas. The most > significant improvement is it's ability to endure Doppler spread found on > paths that cross the polar ionosphere. Both PSK31 and PSK63 fail miserably > in this area; see high-lat test samples below. > > Path Simulation: High Latitude (Moderate) Path Delay: 3ms, Doppler spread > 10Hz > Pangram Text: Quick Brown Fox > > PSK63F -- the quick brown fox jumps over the lazy dog > PSK63 -- mev roe tt#dtorl|f- bn ô mp e o ihe Fzy dg > PSK31 -- nls oSer Òe naAeta qlipM h nV o T rn agâ o > RTTY -- TH QACKH492, FOJUMP OR THTLAZY G > > Sensitivity-wise, it's quite a bit more sensitivity than PSK63, but only > marginally better than PSK31. Although it's speed is about 25% faster than > PSK31, it's about 40% slower than PSK63. Average wmp rate seems to be 63 > wpm > for PSK63F. > > Lowest S/N (sensitivity) > > PSK63F -12db > PSK63 -7db > PSK31 -11db > RTTY -5db > > Additional path tests indicate that PSK31 and PSK63F perform about the same > > under moderate mid-latitude conditions (CCIR fading channel). Tests show > that PSK31 and PSK63F will outperform PSK63 when signals are weak under > quiet conditions since they both have greater sensitivity. > > It would be interesting to hear from our HF digital friends up north who > experience the distorting effects of the polar ionosphere on a regular > basis; this is where the PSK63F mode can be put to the test. > > Available software: > > Nino Porcino's Stream -- http://xoomer.virgilio.it/aporcino/ > Patrick Lindeckers Multipsk -- http://f6cte.free.fr/index_anglais.htm > (thanks for including PSK63F Patrick) > > Tony, K2MO > > > > > >
