Skip, It's good to see that there is a correlation between the path simulator results and real world sensitivity testing. White noise tests show that DominoEX4 does have the same 3db sensitivity advantage you mentioned over DominoEX8 and PSK63F.
> we did extensive testing this morning on 70cm between PSK63F and DominoEx 4, > and DominoEx4, even under > the severe, fast Doppler shift almost always on that band, was significantly > better copy than PSK63F. The minimum > required S/N of PSK63F compared to > DominoEx 4 also hurt its relative performance compared to DominoEx 4 in > QSB. I can see how the minimum SNR would come into play. I know it's easier said than done, but It would be interesting to repeat the tests while signals were adequately above the minimum SNR threshold required for PSK63F and DominoEX8. That would eliminate any signal strength issues and help reveal the true Doppler performance of each mode. It would help to have a recording of the signals so we can analyze the Doppler spread using a high resolution spectrogram. This would give us a better idea of what's going on and should reveal other frequency shifting characteristics such as aircraft Doppler. It would also be useful to have statistical data on the Doppler spread found on over-the-horizon VHF / UHF propagation. Troposcatter seems to be responsible for daily openings on VHF / UHF. I'll have to look on the net. > If you could make simulation tests between PSK63F, DominoEx 4 and DominoEx 8, > it would help us find > out the best mode to recommend for VHF/UHF. We will be making more real world > tests again this week > on both two meters and 70cm. No problem Skip. Tony -K2MO ----- Original Message ----- From: hteller To: digitalradio@yahoogroups.com Sent: Thursday, January 07, 2010 9:17 AM Subject: [digitalradio] Re: IZ8BLY's PSK63F Tony, we did extensive testing this morning on 70cm between PSK63F and DominoEx 4, and DominoEx4, even under the severe, fast Doppler shift almost always on that band, was significantly better copy than PSK63F when signals were just over the noise. The minimum required S/N of PSK63F compared to DominoEx 4 also hurt its relative performance compared to DominoEx 4 in QSB. We did not have time to compare to DominoEx 8, which is roughly the same speed as PSK63F, but our previous tests between DominoEx 4 and DominoEx 8 showed that on VHF and UHF, either SSB or FM, that the 3 dB minimum S/N advantage of DominoEx 4 is very necessary. Signals at 200 miles are almost always just above the noise on SSB phone or DominoEx 4 on 70 cm. That is why operators on those bands are called "weak signal" operators! If you could make simulation tests between PSK63F, DominoEx 4 and DominoEx 8, it would help us find out the best mode to recommend for VHF/UHF. We will be making more real world tests again this week on both two meters and 70cm. 73 Skip KH6TY > __________________________________________________________ > 1a. IZ8BLY's PSK63F > Posted by: "Tony" d...@optonline.net kt2q > Date: Mon Jan 4, 2010 12:52 am ((PST)) > > 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 > >
