Distorted DAX signal in WSJT-X

Ron K2RAS

Dax repeatedly distorts my signal in WSJT-X (with or without any user activity). Closing DAX and restarting it always removes the distortion (see attached screenshot). The distortion comes back minutes to hours later. I am running Win10 19042.1052 under VMWare, and SmartSDR for Windows 2.7.5.

Any assistance is appreciated. Ron K2RAS

Screenshot 2021-06-15 094618.png

David Decoons, wo2x

Can you try on a Windows machine and not in a VM?

Dave wo2x

Ron K2RAS

I will give it a try without the VM. Thanks, Ron

K0FLY

A friend and I have also seen this problem. Here it appears to occur after the PC has been on for an extended length of time (12 to 16 hours) Like you experienced restarting DAX helps for minutes to an hour.

Powering the PC down then back on to gets a much longer FIX, My friends station runs 24/7, he sees it a lot. I do not run VMWare. I can see where some thing like this is hard to trap and fix.

Gayle K0FLY

Ron K2RAS

David, I ran SmartSDR on native Win10 and WSJT-X lost it's DAX connection within an hour (I forgot to mention this also happens on my VM platform). A shutdown and restart of DAX restored the WSJT-X waterfall in Win10.

Ron K2RAS

Bill NE1B

This is known as the DPC issue on Windows 10. It was covered several times on the Community Forum. It happens on some Windows PCs, but not all. Try shutting down all other non-essential programs and just run SmartSDR.

73, Bill NE1B

Bill NE1B

Tim K9WX

I suspect this is related to the latency issue discussed at:

https://helpdesk.flexradio.com/hc/en-us/articles/202118698-Using-LatencyMon-to-collect-DPC-Latency-Data

I see this same phenom from time to time and, like others have reported, I can "fix" it by closing and restarting DAX or closing and restarting SSDR. I've seen it on my FT8 TX signal and my SSB signal.

I have tested my latency using the app described in the referenced web page and I always fail. Even on a brand new home-built PC with a brand new mobo (model was out for only 6 months when I bought it) with all the latest drivers etc. I also failed in the PC that was in previous use, again with up to date drivers. So while this may in fact be a latency issue, I don't think it is necessary always due to old drivers. I have learned to live with it.

Tim K9WX

Ron K2RAS

Thanks for the comments. I plan to move to MacOS as soon as the new M1 Mac Mini is out, it's time to leave W10 behind...

Ron K2RAS

Mike-VA3MW

@Ron K2RAS

Hi Ron, I just want to say something. I use both Windows and MAC OS both all day long. Both have their issues, they are just different. :) Neither is perfect.

For the last week, I have been about 100% on the MAC and there are a few times I though the MacBook pro would do very well skipping across the water off the end of my dock. :)

Enjoy learning a new interface. It does do some other things very well too. (oh, they also force updates that break things).

73

Glenn Depp

I just posted a similar issue but is constant. I had this issue before and had to do a complete install of windows and all the other software I use to get it clear up. Nothing else would work and non clean DAX audio will not allow the software I use to work at all. This is an issue... Again...

Ray G6UJB

Is Flexradio able to indicate if improving the stability of the Windows DAX audio interface is high on Flexradio's todo list please?

I would love to be able to just use a couple of Virtual Machine to run SmartSDR/DAX/Cat to allow me to run my 6600 and 6500 on the same physical computer but DAX sensitivity to latency and its inability to self resync makes this impossible.

73

Erik Carling EI4KF

Flex will not indicate anything as that is their policy. It would be foolhardy to promise that way. Which is not to say that there will not be improvements. It can be done and the TCI CAT and audio carriage protocol is an example. It is outside of the OS audio system, not affected by normal latency, and presents a pure signal to the radio output.

When I first received my 6400M, one of the questions I put on the Forum immediately was about the FT8 signal and that it was not perfect. I improved the situation to one of being acceptable by working on the OS to reduce latency. One of the most effective tools I found is Intelligent Standby List Cleaner which automatically clears the memory standby list and working set. These grow over time and reach the point where the OS internal timer is out of whack, leading to audio issues that need a stop start of the application or even the computer. ISLC will purge memory at a certain threshold and using this I had little residual problem.

But then I changed to Windows 11. No DAX issues at all, even without ISLC. I do not suppose it has anything to do with W11 per se, I think it is because I did a fresh install of the OS (followed by the normal latency reduction techniques of disabling dynamic tick and so on that always seem rather esoteric but actually are important). Anyway, it did show me that over time the OS seems to acquire crud that makes latency worse and it can help to do a fresh install.

Flex are great but they don't have a magic wand and when needed you have to do the research and make things better yourself.

Ray G6UJB

I tried using win 11 preview in my VM environment and DAX suffers from the same problem. other multimedia apps seem to be able to work smoothly in the VM just not DAX. Its all extremely curious.

No magic wands here Erik.

Done all the research, done all the tweaks. Now waiting for a real solution, if it ever arrives before the hardware is EOL.

73

Ted VE3TRQ

| “other multimedia apps seem to be able to work smoothly in the VM just not DAX”

Although I agree that it would be nice if Dax were a bit more resilient, remember that Dax is not just another multimedia app. Multimedia apps are designed to deal with delays and latency by buffering content. Dax is (or at least attempts to be) “real time” and is pretty intolerant of delays, and especially varying latency. You will see delays and latency as gaps in data as a result of minimal buffering to retain that pretty much real time. Windows is especially egregious in its treatment of data latency - it sure is not a real time O/S.

I hope I am not stating the obvious to you. I mostly use MacOS and Linux and really don’t see all that much latency introduced by the network and operating systems.

Ray G6UJB

I don't have the luxury of a Mac. And I was only curious.

KM4CQG

For several years I have had this issue. I it solve it by closing DAX and restarting DAX.

It also effects other digital modes PSK31 and SSTV Dax is corrupted by something in Windows that I have yet to figure out. VM is off and power saving as well.

Ian

Bill NE1B

Windows DPC issue! See the article below:

https://helpdesk.flexradio.com/hc/en-us/articles/202118698-Using-LatencyMon-to-collect-DPC-Latency-Data

73,

Bill, NE1B

bahillen

I have had this issue with a band of noise being generated after the 6600 has been on for many days. 6600, 3.2.39, Windows 10, Dell I7-7700 16GB of RAM. I I leave my 6600 on 24/7. I monitor bands all night FT8 . It is a pain because it is not apparent that I am transmitting 3 KHZ of noise without seeing it on the waterfall and some audio distortion. I found I don't have to restart DAX, I just have to hit the TX button to turn it off and hit it a second time to turn it back on. Problem goes away for several days. so now I have a habit of hitting the DAX TX button twice and it clears the memory or corruption. My 6600 is dedicated computer for the Flex and associated software.

I have gone through many days of testing with Latency Mon and fixed many drivers that I keep up to-date. Added RAM and many other things. Tim was a big help in that regard. The problem did get better as a DAX update was made but is still there. It would seem a simple thing to have a DAX of sequence once a day during receive to clear the buffer or what ever is the driver problem.

It is my understanding that the DAX driver was contracted from an outside supplier at the time and probably still so.

73

Bill W9JJB

Patrick

Shutting down DAX and restarting it will clear up the problem. It is not necessary to shut down the radio or do a factory reset to clear the problem. I have experienced this also and this issue should be addressed by Flex. Prior to the last two versions of SmartSDR, the radio would freeze after long periods of continuous unattended operation. They fixed it but, DAX started to act the same way, not sure if there is a connection or was hidden by or related to the SmartSDR operational SW.

David Decoons, wo2x

This can be caused by the PC having high DPC latency.

you can use Latency Monitor and let it run in the background to see if that is the cause.

73

Dave wo2x