FT8: Lots of signals in waterfall but decoding only a fraction of them

Discussion in 'Working Different Modes' started by KD3LT, Jul 7, 2019.

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  1. KD3LT

    KD3LT Ham Member QRZ Page

    That's pretty much it. Using WSJT-X 2.0.1 on Windows 10. Microphone (CODEC) input signal level is at 61, which worked well before.

    When I switch the Signalink output to a laptop running Linux Mint (same USB cable), I get many more signals decoded, so the problem appears to be somewhere in the Windows machine. But where?

    Edited to add: the decoding appears to be independent of signal strength: out of what appears to be a dozen signals on the waterfall, it might decode a +2 and a -19.

  2. NK7Z

    NK7Z Premium Subscriber QRZ Page

    Have you checked the time setting for Windows? WSJT-X is somewhat critical about time...
  3. KD3LT

    KD3LT Ham Member QRZ Page

    Thanks. This may indeed be the problem: although I've specified time.nist.gov for "Internet Time" for the computer, the actual computer time is about 3 seconds ahead of the time displayed at time.gov. That's surely enough to derail almost all FT8 signals.

    Interestingly enough, when I go into the Windows date/time settings to try to select a different server to synchronize Windows 10 to, I get an error. I have no idea why at this point, only that my computer clock continues to be a few seconds off the FT8 beat.

    Maybe the clock battery on the motherboard is coughing up its cookies?
  4. KV6O

    KV6O Ham Member QRZ Page

    Try Dimension 4, you can easily adjust how often to sync with the time server of your choice. Windows probably doesn't do it all that often.
  5. NK7Z

    NK7Z Premium Subscriber QRZ Page

    I use D4 as well.
  6. KD3LT

    KD3LT Ham Member QRZ Page

    Yes, Windows goes all coy and vague about how often it syncs with the specified time server. I checked the Windows Time Service itself and discovered that it was set on "Manual" and apparently not running all the time, so I switched it to "Automatic" and rebooted. (I had rebooted several times earlier to no apparent effect.)

    Presto: the times now march together again; and bingo: I'm reminded why I prefer 17 meters in the middle of the day.

    Now back to the problem of trying to use a 102 ft. doublet on 17 meters, a/k/a "How much more hardware I can hang in the air before my wife will want to hang me from it?"

    Grateful thanks.
  7. VA3VF

    VA3VF Ham Member QRZ Page

    First order of business: disable Windows time sync, as it's useless.

    I have used and recommended Dimension 4 for almost 10 years. However my new favorite is NetTime. Either will do. Try and see which one you like. If you plan on sync'ing off GPS, then go with BktTimeSync.
  8. N3AT

    N3AT Ham Member QRZ Page

    Meinberg packages up the official NTP software nicely. I don't need this for my Window 10 so much, I just set the time before starting a digital session. However, for Windows 7 (needed for my Flex SDR-1000) it is impossible to get closer then 1.5 seconds with the OS time software. Meinberg got me spot on.

  9. AA4PB

    AA4PB Ham Member QRZ Page

    I think the default for Windows 10 time sync is once per week or any time you reboot the computer or manually sync it. I use Dimension 4 set to sync every 15 minutes. It has always worked without issue for me so I've never tried any of the others.
  10. KD3LT

    KD3LT Ham Member QRZ Page

    This is turning out to be an interesting issue: MS acknowledges that earlier versions, i.e., pre-Windows 10/Windows Server 2016 indeed "cannot guarantee highly accurate time..."

    They do claim that with current updated versions, accuracy to within 1ms is possible if configured properly. Of course, that sort of configuration for 1 ms accuracy is beyond what I'm willing to go for.

    They are still coy about how often the external time signal is synced to under normal operations, but having changed the startup environment so that Windows Time Service is automatically launched at startup rather than being "demand driven", i.e., whenever Windows feels like it, I'll be interested to see if it continues to keep good time. I can still of course go for the external vendor solution.

    The relevant MS document is at:


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