Thanks. I'll try that. 73, Frank KF6E
On Thu, Jan 3, 2019, 11:42 Patrick 9A5CW <[email protected] wrote: > Hi Frank, > You can try to download 2Tone for RTTY. > So far best decoder was made for MSDOS by K6STI Bitty and Ritty. That was > better than any Windows or so RTTY software nowdays. > > Best 73 > Patrik 9A5CW > > > Datuma čet, 3. sij 2019. 17:14 Frank Kirschner <[email protected] > piše: > >> Hi, Bill, >> >> Thanks for your reply. >> >> I wasn't suggesting a change to the standard for RTTY, which, of course, >> would be impossible at this point. I was pointing out that the software I >> have used to decode RTTY is nowhere close to the theoretical limit, or even >> the hardware discriminator I built years ago. DM780 and MMTTY, the two >> programs I remember using, require very high signal to noise ratios to >> provide even moderately good decoding. >> >> Do you have a recommendation on software that might perform better than >> what I am using? >> >> I first used RTTY in the late 1960s, when I had my home-brew TU and a >> Kleinschmidt teleprinter, so I'm familiar with the electro-mechanical >> technology for which Baudot code was designed. I designed a weather >> collection network for Thailand in the early 1970s that used mechanical >> teleprinters and prepared tape messages. It was a bit of a kluge, but it >> worked for years. >> >> 73, >> Frank >> KF6E >> >> On Thu, Jan 3, 2019 at 10:52 AM Bill Somerville <[email protected]> >> wrote: >> >>> On 03/01/2019 15:33, Frank Kirschner wrote: >>> > Many years ago, I had a home-brew RTTY TU. It had two 88 mH torroids >>> > in the tuned circuits and a differential amplifier as a detector. >>> > Occasionally, the received signal would fade below the noise, but the >>> > Kleinschmidt teleprinter would keep printing the decoded text. I have >>> > tried several current software packages for decoding RTTY signals, and >>> > all of them require quite strong signals to decode at all, and very >>> > strong signals to provide 100% print. >>> > >>> > I was wondering if the decoding method used in WSJT-X for FT8 could be >>> > ported to a RTTY decoder. I realize that FT8 has a lower symbol rate, >>> > which provides more time to integrate, and incorporates redundancy, >>> > which improves accuracy. But the theoretical lower limit for decoding >>> > RTTY is something like -5 dB S/N, and the current programs are nowhere >>> > near that. >>> > >>> > If RTTY facilities could be integrated with WSJT-X, not only would the >>> > decoding be better, but the log scanning functions of WSJT-X and >>> > JTAlert would be better, significantly improving contest operation. >>> > >>> > I confess I haven't looked at the decoding techniques used by RTTY >>> > software, but I suspect, based on performance, that it could be >>> improved. >>> > >>> > 73, >>> > Frank >>> > KF6E >>> > >>> Hi Frank, >>> >>> this is well covered ground, some existing Baudot decoders have very >>> good performance with built in weak and fading signal models to optimize >>> them. >>> >>> The techniques used to decode FT8 are based around a block message >>> format that includes parity bits and checksums for advanced forward >>> error detection and correction, Baudot is a character based stream code >>> with no forward error correction capability. RTTY was designed for an >>> era where automation was mechanical and quite limited, just having a >>> code that could be used to modulate a transmitter and be printed by a >>> receiver was about the sum of the technical design. RTTY's *only* >>> similarity with FT8 is that it is a frequency shift keyed constant >>> amplitude signal. Even the simplest addition of a single parity bit to >>> detect, but not correct, single bit errors would need a fundamental >>> non-backwards compatible change to the Baudot code. >>> >>> 73 >>> Bill >>> G4WJS. >>> >>> >>> >>> _______________________________________________ >>> wsjt-devel mailing list >>> [email protected] >>> https://lists.sourceforge.net/lists/listinfo/wsjt-devel >>> >> _______________________________________________ >> wsjt-devel mailing list >> [email protected] >> https://lists.sourceforge.net/lists/listinfo/wsjt-devel >> > _______________________________________________ > wsjt-devel mailing list > [email protected] > https://lists.sourceforge.net/lists/listinfo/wsjt-devel >
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