Windows only or all platforms? Scott W1ssn Sent from my iPhone
> On May 3, 2019, at 4:58 PM, Bill Somerville <[email protected]> wrote: > >> On 03/05/2019 21:24, Reino Talarmo wrote: >> Hi, >> >> Thanks for an excellent piece of communication protocol both FT8 and FT4. It >> would be interesting to see how big guns start to use FT4 instead of RTTY. >> For strong signals RTTY is a bit faster than FT8, but most of the users are >> not big guns! The bandwidth saving in FT4 is a really big issue, so there >> will be many more QSOs/min/kHz. >> >> I checked how much timing difference is allowed for a successful decode. It >> seems that in 23000 successful decodes timing difference is in range -0.5 s >> to 0.6 s. In FT8 the range is -2.6 s to 2.5 s and 99% of successful decodes >> are within +/-2 s compared to my timing. I have no idea how much signal >> strength affects to the result, but for sure in FT4 any practical signal >> strength increase does not help to extend the range outside the +/- 0.5 s. >> There are many signals that fall out of that range. So we could recommend >> clock accuracy +/- 0.25 s or better for FT4. >> >> 73, Reino oh3ma >> > Hi Reino, > > your conclusions are all correct. We are currently fine tuning the FT4 > transmission start time so that the decoder gets a reasonably even chance of > decoding signals across the allowable DT tolerance of ± 0.5 S without losing > sensitivity. We can't quite make it perfect across that range whilst still > allowing the user reasonable thinking time before the next transmission > period. FT4 has a shorter transmission time, shorter dead time between > periods, and shorter periods than FT8 so it should not be surprising that > clock accuracy requirements are stricter as well. This really only matters > for MS Windows users who have not bothered to install a third-party NTP > service, have no suitable Internet connection, or GPS signal. For those that > rely on manual time setting or think Windows can do the job well enough, now > is the time to think again. > > 73 > Bill > G4WJS. > > _______________________________________________ > wsjt-devel mailing list > [email protected] > https://lists.sourceforge.net/lists/listinfo/wsjt-devel
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