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_____ Von: [email protected] [mailto:[email protected]] Im Auftrag von Dave AA6YQ Gesendet: Freitag, 22. Januar 2010 23:06 An: [email protected] Betreff: RE: [digitalradio] Re: Comparison of RTTY software sensitivity MMTTY provides a choice of three different RTTY decoders, with the ability to shape the filters for each. There is also an optional bandpass filter and an optional notch filter, with user control of shape for each. As a first step in improving MMTTYs RTTY decoding performance, I am determining how to optimize performance given the capabilities Mako-san JE3HHT has already provided, using a setup similar to what Alex VE3NEA and Wes WZ7I have used. Note that on the chart Wes posted, WinWarbler running the HyperSensitive profile with both the bandpass and notch filters enabled yields sensitivity close to that of TrueTTY. WinWarbler uses MMTTY as its RTTY engine, so this performance is possible with MMTTY alone. I don´t have winwarbler but have mmtty . Can somebody make a text how to setup mmtty for the hyper sensitive profile that I can store it I mmtty as user profile???? MANY THANKS DG9BFC SIGI By synchronous detection, Vojtech, do you mean treating the first start bit as the beginning of a synchronous multi-character sequence, thereby providing some protection against broken start and stop bits within that sequence? Brian K6STI referred to his decoding technique as employing a flywheel, which I interpreted as a means of adjusting the synchronous timing with high-quality start bits decoded within the sequence. 73, Dave, AA6YQ From: [email protected] [mailto:[email protected]] On Behalf Of Vojtech Sent: Friday, January 22, 2010 8:27 AM To: [email protected] Subject: [digitalradio] Re: Comparison of RTTY software sensitivity Here is another, similar chart: http://www.dxatlas. <http://www.dxatlas.com/RttyCompare/> com/RttyCompare/ I was comparing MMTTY with MultiPSK and gMFSK against RTTY in white noise. Interesting observation was that MMTTY was better than MultiPSK at better than marginal SNR, but MultiPSK was slightly better than MMTTY at very low SNR. My best bet is that MMTTY is doing some kind of signal processing after detector, which fixes some errors, but makes things worse in very low SNR. Both yours and Alex's graphs show superiority of TrueRTTY and MixW. I wonder whether TrueRTTY is doing synchronous detection. This is what I plan to try when I retire, hi. 73, Vojtech OK1IAK No virus found in this incoming message. Checked by AVG - www.avg.com Version: 9.0.730 / Virus Database: 271.1.1/2636 - Release Date: 01/21/10 15:34:00
