Thanks for the tests, Tony. The numbers confirm what NC5O and I found yesterday with our on-the-air comparisons between MFTTY, PSK31, PSK63, PSK125, and MFSK16 over a period of four hours and changing band conditions. We could communicate on PSK31 long after MFTTY had quit decoding, and solid copy using MFSK16 (but with a wider bandwidth, of course) when PSK31 started producing errors.
73, Skip KH6TY ----- Original Message ----- From: "Tony" <d...@optonline.net> To: <digitalradio@yahoogroups.com> Sent: Saturday, January 17, 2009 3:59 AM Subject: [digitalradio] MFTTY - HF Path Simulations > All, > > I was able to take some time to test MFTTY with the HF path simulator this > evening. I added a few commonly use modes for comparison. As expected, the > slower / narrow MFTTY modes seemed to have a definite weak signal > advantage over the faster ones. > > The minimum SNR test showed a wide 12db gap in sensitivity between 1/8 > speed and double speed modes. This should show when testing the different > MFTTY modes on the air. > > In the HF simulator tests, each mode was subjected to same HF path > distortion. The less tolerable a mode is to this distortion, the greater > the throughput errors. > > It would seem that MFTTY would compare well with other more robust modes > if the character speed is kept down using the half and quarter speed > modes. At least that's what the HF simulator seemed to indicate. > > I'd appreciate hearing about on-air tests from you all so I can compare > some real data to the simulators. > > Thanks, > > Tony -K2MO > > > Minimum SNR > > MFTTY > Double Speed -5db > Normal Speed -7db > 1/2 Speed -9db > 1/4 Speed -13db > 1/8 Speed -17db > > > MFSK16 -14db > Olivia 500/16 -13db > PSK31 -10db > RTTY -dab > > > > Path Simulations > > Path Simulation: > Mid Latitude Disturbed > SNR -8db > > Mode Throughput > > Double Speed <10% > Normal Speed 10% > 1/2 Speed 25% > 1/4 Speed 50% > 1/8 Speed 85% > > MFSK16 100% > Olivia 500/16 100% > PSK31 70% > RTTY 45 20% > > ___________________ > > Selective Fading > SNR -8db > > Double Speed 10% > Normal Speed 30% > Half Speed 45% > Quarter Speed 60% > Eighth Speed 70% > > MFSK16 90% > Olivia 500/15 100% > PSK31 65% > RTTY 45 25% > > > > No virus found in this incoming message. > Checked by AVG - http://www.avg.com > Version: 8.0.138 / Virus Database: 270.10.8/1898 - Release Date: 1/16/2009 > 3:09 PM > >
