SmartSDR 3.1.8 loses signal sharpness, then cannot copy FT8

AB4EJ

Since upgrading from SmartSDR V2 to V3.1.8, I have noticed that if the radio is used for a while (> 30 minutes) to copy FT8 signals, the signals from individual stations go from being sharp and copyable to being a fuzzy mass which WSJT-x cannot copy (see screen shot of FT8 waterfall before and after a restart of SmartSDR). If I simply restart SmartSDR, the signals become sharp again  and WSJT-x can copy the sending stations. Is  this a known problem, with a solution? Are other people noticing this?

Mike-VA3MW

Hi Bill

I would have to say no at this point.  Just one thing you might try, if you haven't already, would be to do a clean reboot on things and see if that clears it up.

I worked  a TON of people last night on 6M without issue.

Let me know how it goes.

Mike va3mw

Phil Moore M0TZZ

Not seen this and I work a lot of FT8

Al K0VM

Bill, 
  I have seen that on rare occasion that I recover by either toggling the RX slice button in the DAX GUI, or by closing and restarting the DAX GUI..  
Also suggest verifying that the DAX drivers are version 3.1.0.5 ( Windows Device Manager>Sound video and gaming>Flex...DAX... >Properties>Driver )

AL, K0VM

Mika Rintala

I have seen this problem. 
Mika/OH6MR

Larry Benoit

Bill,

While I haven't experienced your exact problem, I had a mysterious and gradual decline in the number of decoded signals until none were decoded  after running FT8 for a few hours. It turned out my anti-virus scanner was causing latency in processing the temporary files that WSJT-X employs to decode signals. I excluded the ....AppData/Local/WSJT-X folder from scanning and the problem was solved.  While your issue is probably caused by something altogether different, try disabling your anti-virus while using WSJT-X.

Good luck and 73,
Larry KB1VFU

AB4EJ

I tried a "clean reboot" - which consisted of powering down the Flex6600 and removing 12v from it for a few minutes. The problem returns: signals become fuzzy after some time (don't yet know exactly how long). I will try disabling anti-virus and see if this makes a difference...

AB4EJ

BTW - I did check driver versions - they are at 3.1.0.5.

AB4EJ

An update - I verified that my drivers are V3.1.0.5.  I tried running FT8 with anti-virus scanning disabled - this made no difference. The problem persists. I have a work-around: if the system has been left running for 30 minutes or more, I restart SmartSDR. I am going to further characterize the problem to see if I can narrow it down; preliminary evidence suggests that something is increasing the jitter in clock timing...

KD0RC

Interesting...  Are you by chance using a GSPDO?  If so, internal or external?
73,
Len, KD0RC

Al K0VM

What does the WSJT-X Wide graph look like with N Avg set to 1 or 2 ?   It sounds to me like DAX buffer corruption.  Close and restart the DAX GUI.
AL, K0VM

Bill W2PKY

If you have speakers or headphones hooked up to the PC bring up Sound Control Panel>Recording tab and locate the DAX Audio RX channel associated with WSJT-X; right click on channel and select properties; then click on listen box, click okay and listen to the audio quality. See if the signals sound
different when the waterfall changes.
 

Dave - WB5NHL

I also have seen this from time to time. Stopping and Restarting DAX always cleared it up. However, it has been awhile since it's occured.

AB4EJ

I am not running a GPSDO.   - Bill, AB4EJ

KD0RC

OK. I was taking a shot in the dark that maybe a jittery GPSDO was causing the problem.
Len

AB4EJ

In response to post by K0VM, I tried a couple of things:
1. I changed the N Avg to 2 (from 5).  Immediately I see that the signals become faint and fuzzy:

Here we see that changing from the default (N Avg 5) to N Avg 2 makes the signals appear faint and fuzzy; when you switch back to N Av 5, the signals become slightly stronger but they remain fuzzy.
2. Stopping and restarting DAX GUI does fix the problem, both improving signal strength and clarity:


This is hard to understand - is there some kind of interaction between DAX and WSJT-x that affects the signal processing, and it is somehow related to the N Avg setting?

Does WSJT-x have a featurebug that dynamically adjusts the N Avg setting in certain cases?

Al K0VM

Bill,
  Okay it appears that you are seeing the DAX buffer corruption issue more frequently than other are seeing  it.   DAX has buffers that run on the PC that are intended to handle the clock differences between the radio and the PC, and the jitter inherent in the serial ( ethernet) path that the data takes. The buffers can become corrupted and cause the symptoms that you are seeing.  Closing and restarting the GUI also resets the buffers.
  Changing the N Avg does not change the buffer corruption or the data that the ft8 decoders use.  It only effects what you see on Wide Graph water fall.

  I am at a loss as to why you see the corruption more frequently that most of us..   I typically see it less than once every couple of weeks I run 24/7.  It might be something unique to your PC hardware or CPU loading... 

AL, K0VM

Sergey KN7K

I also see that issue time to time.
I used to zoom out and zoom in on panadapter and eventually it would be sharp again.
Weird...
Sergey, KN7K

Bill W2PKY

Some PCs can not run DAX under Win10. This has been discussed at nauseam when Win10 first cam out. An example is my ASUS Z97A 4790K motherboard. with Win 10 Pro installed DAX will run for a short time and one by one the receive channels get corrupt. Tried all sorts of tricks with the O/S to no avail. Had to go back to Win7 Pro. Obviously, do not know if this is your problem for sure but if you search around the community you will find posts where many had to stay with Win7. 

My 2 Surface Pro tablets run Win 10/DAX with no issue.

What computer are you running? Did it come with Win10?

Finally, are you certain prior versions of SSDR ran ok on your computer.

AB4EJ

Hmm... something is going wrong in DAX.  I left it running while eating lunch (it was working before), and it  crashed or hung up (WSJT-x kept running just showing the red dashes in the waterfall indicating no signal data) - restarting DAX started everything working again. Holy mackerel - the moment I restarted it, I worked Haiti on 6M, which is a new grid and a new country. ...  So what to do if I wish to let the rig observe propagation overnight? - maybe build a timer that restarts DAX every so many minutes - ugh, what a kludge that would be.  I will continue to try and characterize the problem - maybe enough evidence can be compiled to give the FlexRadio software guys something to work with on troubleshooting...

Tim - W4TME

You are averaging less so the signal is losing resolution.  This is to be expected.  It the way the math works.

K6HN

As silly as it might seem, the reset DAX timer app is what I had to do with an earlier release of DAX. Every hour it would close and restart DAX. I had the same issue you are seeing and it was happening every hour or so.  With the latest version of DAX it only happens every couple of days if I leave the radio on 24x7 so I do not have to use the reset timer app.

AB4EJ

The PC I am using is a Dell XPS 8920, which came with Windows 10 pre-installed. The previous version of SmartSDR did not have this problem. I am going to downgrade to version 2, as I have several things coming up for which DAX needs to work continuously for many hours.

AB4EJ

A couple of updates - first - as far as I can tell, I have been able to solve the problem by downgrading back to SmartSDR v2.6.1. At first, I thought it might be the DAX drivers; but for this version what got installed was v 3.1.0.5 (same as I was running with v.3).  Maybe version 3 is just not ready for prime time yet (at least, for FT8 and things like the ARRL FMT[Frequency Measuring Test]).

Another thing I noticed - running v 3, the frequency of the rig would move around + / - about 1/2 Hz, with a period of 1 to 3 minutes. I noticed this observing both WWV and using a GPS-controlled signal generator; so doing things like participating in FMT and observing ionospheric movements appearing in the Doppler shift of WWV weren't workable, I don't see that running v 2. This is verified with data collected using both fldigi and SpectrumLab.

AB4EJ

Oops - I spoke too soon.  The v2 system lost its mind after a couple of hours and resumed creating a splatter of frequencies, Will report further when I have more details....

AB4EJ

Here is a result of monitoring the frequency of WWV (10MHz) overnight. The plots are in the frequency domain (using frequency analysis mode of fldigi V 4.1.11.18). An overview shows a couple of places where DAX entered what I call "Failure mode 1" - wide frequency excursions on either side of the actual frequency; you can see where the system then transitions to Failure mode 2, which is frequency errors on just one side of the actual frequency. Transitions to Failure mode 1 are spontaneous and the mode persists until I restart DAX. There is one time where the system spontaneously goes to Failure mode 2 and then back to normal:

A closer look at Failure Mode 1 looks to me like there may be a pattern to the noise:

Since this frequency jitter is readily fixed by simply stopping & starting DAX, it doesn't seem to be related to the FlexRadio's ability to stay on frequency, but rather some noise getting mixed into DAX from somewhere.... any other thoughts?

WK2Y

Noise on the power supply?

Bill W2PKY

As many Ops have found some PCs can not run DAX reliably  using Win10 OS. Is it possible to try another PC, maybe running Win7?

AB4EJ

I thought about this, but it is hard for me to imagine that noise on power supply would instantly be cured by simply restarting DAX. Also, this is a frequency jitter; I would expect noise to show up as an amplitude.

AB4EJ

This is the only PC I have, and was working fine with the FlexRadio 6600 and Smart SDR v2 since I bought the Flex new in March of 2019. This problem showed up about the same time I upgraded to SmartSDR V3, but I can't necessarily blame V3 because (a) Windows gets frequent updates also and (b) I had an intermittent hardware problem with the 6600 (repaired under warranty), so I know it is possible that it is hardware, but I would be surprised if a restart of DAX would fix a hardware problem. So still a mystery. I will try shutting down a lot of other things that are running (I run a big, complex system) and see if I can associate the problem with something else going on...

Sergey KN7K

How do you guys restart the DAX? I usually restart SSDR.
Thanks
Sergey, KN7K