On Tue, Jan 14, 2020 at 11:32 PM David Gilbert <[email protected]> wrote:
> > What would that be? FT8/FT4 uses a better detection scheme than RTTY > precisely because of the constraints that FT8/FT4 require. Those > constraints are what allow the better decoding ... there is no "magic" > involved here. > > No one suggested magic. The program has MFSK as one mode option. (It has many modes, not just FT8.) RTTY uses BFSK, and BFSK is a subset of MFSK. In order to discriminate which tone is being sent, there is an algorithm the program uses. Some algorithms are better than others. If you look at the various RTTY programs available, you will see a considerable variation in error rate vs. S/N. DM780, for example, requires an S5 signal to get reasonably good print, and around S9 for 100% print. Others are slightly better. My thought was that the frequency discrimination algorithm in WSJT-X is better in the presence of noise than most of the other programs available. (I've hear the word, "bins" used, so I suspect that FFT is at the heart of the discriminator.) Using this as the heart of a RTTY program might provide an improvement in performance on RTTY in the presence of noise. I understand that RTTY doesn't use or allow the redundancy and error correction techniques found in FT8, so the performance will never approach that of FT8. But it could be improved. Many years ago, I used a T/U with tuned circuits using 88 mH toroids, and Kleinschmidt teletype equipment, and could get very good print even when the signal faded below my ability to hear it in the headphones. I haven't found a single program currently available that approaches that. I understand that there is finite time available for programmers. For me, as a user, WSJT-X works splendidly, and short of printing out QSL cards, putting stamps on them, and taking them to the post office, I don't know what else it could do for my operating practice. Since WSJT-X is now used in RTTY contests, it seems like it would be a natural fit to add a RTTY window to the program. The UI is completely different, but much simpler for RTTY. An alternative might be for someone who already knows the code in WSJT-X to write a small external program that is called when "RTTY" is selected as the mode in WSJT-X. Since WSJT-X is used in RTTY contests, this would make it more convenient. Is WSJT-X more of a test bed for experimenting with new communications modes or a T/U program intended for daily and contest use by hams? Of course, the developers make the choice as to the mix. I was simply stating my preference as one ham among many. 73, Frank KF6E
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