FT8 stops decoding

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  • Updated 1 month ago
  • (Edited)
Started having problems with FT8 where decoding would randomly stop for long periods at a time. This was happening on all bands at the same time.

I was using Windows 8.1 and SSDR 2.3.9 so I figured it was time to upgrade. Went and bought a new Windows 10 computer and loaded both SSDR 2.3.9 and 2.4.9 with a fresh install of WSJT-X 2.0. All worked well for a few days then the decoding issue started again. It worked great last night and early this morning but then stopped decoding again.

I replaced my Ethernet cable, rebooted the cable modem , 6700 and PC several times. I also upgraded/downgraded SSDR between 2.3.9 and 2.4.9 several times and did factory resets as well. I adjusted RX gains and audio levels up/down many times.

I also tried variations of decode parms in WSJT-X but nothing is working. It only decodes one or two signals every 20 minutes or so while the band is loaded with FT8 activity.

I also installed a time sync app to make sure it wasn't a clock issue and my clock matches time.gov exactly.

To recap - new computer with all updates loaded before installing SSDR, tried numerous upgrades/downgrades, reboots, bands, slices, audio settings, etc.

I also removed and reinstalled WSJT-X just in case that was the problem.

Any suggestions besides opening a ticket?



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Pat N6PAT

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Posted 3 months ago

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Photo of K1UO - Larry

K1UO - Larry

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Stop and restart DAX....    DAX sometimes tends to "go asleep"
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Pat N6PAT

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did that many times
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Lou Dietrich

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1. Is your PC's time in sync? Ruinning Dimension4 or some other clock sync program?
2. In the DAX window, do you see streaming audio?
3. In the WSJT-x/ JTDX waterfall, do you see audio?
4. As Larry K1UO suggested, restart DAX,
5. On those you are decoding what is the DT? (Time differential?)
6. Any other program running which want to use the DAX audio stream?

Highly doubt any problem with the rig or SSDR. Sounds like either a timing issue...or DAX. 

73

Lou N2TU



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Pat N6PAT

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1. time is exact
2. yes
3. yes
4. did that many times
5. between 0.0 and 0.5
6. no
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Bill Barber

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You did not mention what configuration you are in. For example, remote via SmartLink or local computer on the same switch with the radio.   I have also been having the same WSJT-X decoding "sleep" mode, locally on same switch.  In most cases, it happens after I have changed bands.  The WSJT-X waterfall shows a loaded band, but no or few decodes.  The DAX window shows receive audio going to WSJT-X.  The WSJT-X app shows incoming audio level also. 

In the past, just a restart of DAX would resolve the issue.  Now, however, that by itself does not resolve it.   But doing a shutdown of SmartSDR and re-connecting to the radio, wakes up the decoding again.

I suspect this is not a radio or WSJT-X issue, but rather a Windows 10 computer  "sound card" issue with the handling of DAX.

For now, this is my workaround.  Not elegant.  Maybe there is some configuration that I am missing to "keep alive" the DAX circuit.


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Pat N6PAT

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Yes I did mention I am using an Ethernet cable. Yes, I did restart everything including DAX many times
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Rick - W5FCX

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Sounds like a time drift issue based on the description. If you aren’t using the Meinberg NTP time sync program give it a try. It resolved the time drift problem for me which has not resurfaced.
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Pat N6PAT

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As I said I;m using a time sync app and my time is exact according to time.gov
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Ria - N2RJ, Elmer

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It sounds like the bug in WSJT-X I've been experiencing. It would stop decoding after a long time. Restarting WSJT-X would fix it. Very sporadic. Happens both with my Windows physical PC at home and also Parallels on my macbook Pro 2018. 
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Pat N6PAT

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Sadly, restarting WSJT-X does not help.

I do notice  that when I start SSDR it uses about 150M of main memory then starts creeping up to over 800M if I leave it on for a few hours. Why is it using so much more memory?
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Pat N6PAT

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Now it suddenly started working 5 minutes ago.

Also, I restarted SSDR 30 minutes ago and it went from 156M to almost 600M in main memory usage. Why is it climbing and so quickly?
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Ria - N2RJ, Elmer

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That would be a question for the engineering team. It could also be DAX corruption which is a well known issue.
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Pat N6PAT

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My neighbor across the street was doing stuff in his garage all morning and the minute he stopped and drove away it started working on all bands. I wonder if he was doing something that was causing interference.
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Pat - WH6HI

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There is a new update to wsjt-x version 2.0.1 available. Also JTAlert has update.....
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Steven Linley

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Just saw your post. That is what I was thinking,that maybe you weren't using version 2.0
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Pat N6PAT

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I am using 2.0
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Pat N6PAT

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fyi...it stopped working again. I also tried with 2.0.1 and the results were the same.

When it works it works very well but then suddenly stops completely
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Lou Dietrich

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Have you tied JTDX....try is and let's hear your results.
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Pat N6PAT

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I installed JTDX and it also will not decode. I set the audio to where it says to set the level.

I again checked my clock against several sites and it is exact. However, I noticed that the time displayed on the main SSDR window is about 1 second slow.
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Pat N6PAT

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It's now working. I cleared everything out and rebooted several times. I'm not sure what the problem ws but it's fine now. DT's re between 0.0 and 0.7 so the clock was not the issue

JTDX is also working now so I can compare the two to see which decodes better.

Thanks for al the suggestions.

73 Pat
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Pat N6PAT

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Just turned on the radio for the first time today and now it's back to not decoding! No changes to audio levels or any other settings since last night when it was working fine. 

I don't know if this is the cause but the clock on the bottom of the SSDR window is always 1 second behind the clock on the computer. I don't know what is causing the lag.

This is so frustrating!!
(Edited)
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Arvind Mallya

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Pat, Here is a simple tip, I found the Windows clock drift about 1-2 seconds. First log into www.time.is and check your clock accuracy. If it is 2-3 seconds off go into windows Date and Time settings, set it to UTC, next move the sliders for set time automatically and set time zone automatically to On. I found it to sych sometimes exactly or off by 0.2 seconds. I'm then able to decode without problems.
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Tim - W4TME, Customer Experience Manager

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Or install Meinberg and never worry about it ever again
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Pat N6PAT

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I use Meinberg. This is an oscillator issue if you recall. Flex received my 6700 today to repair and re-calibrate. Ticket 30454 .