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DAX distortion

My radio is on 24/7. Occasionally I find that when I transmit on DAX, There is terrible noise/distortion that occupies the entire TX bandwidth.  I used to resolve this by cycling power to the radio, but I have found that disabling and re enabling the DAX audio stream corrects this.  This doesn't happen often, but it can happen mid QSO.

Attached are screenshots of the transmitted signal. On the left, the signal with the noise/distortion; on the right, a normal signal. (The vertical scale was adjusted between screen captures).  Single tone 'TUNE' carrier is from WSJT-X v1.3, r3673.


Radio Flex 6700, software v1.4.3.132

Open for Comments · Last Updated


  • Dave -- W7IWWDave -- W7IWW Member
    edited June 2018
    Have experienced same situation running PSK31 (HRD v. 6.2), and have resolved the transmit distortion by disabling and restarting the DAX channel.  Anxious to learn if others have experienced same, and if FRS is aware possibly correcting issue in future s/w update??  Or advise on how to "permanently" correct issue locally??
  • George Molnar, KF2TGeorge Molnar, KF2T Member ✭✭✭
    edited February 2019
    I've seen it too. It's rare, but real, and Dave's workaround does the trick. Probably some little gremlin in the DAXWorks...
  • Sergey R5AUSergey R5AU Sergey Member ✭✭
    edited April 2017
    I have similar problems on my previous iMac27(from 2010) with any Virtual Machine, however on the native Win PC or my new iMac27 5k with any VM I have not any more such issue.
  • PatrickPatrick WH6HI Member ✭✭
    edited June 2
    One thing that can help with noise and distortion is to adjust the Pwr Slider on the right side of the App window and set it so that it is something around half way then adjust the levels with DAX Channel. Some adjustment of the power slider in SmartSDR may be required.  For me this has resulted in a much cleaner signal output.
  • PatrickPatrick WH6HI Member ✭✭
    edited June 2
    On just a couple of times I have had distortion from DAX cause major IMD that spread up and down thr JT65 band.  I noticed it right away thanks to being able to see the transmit waveform.  Rebooted SmartSDR and the Radio and that cured it.  But also applied the what I did in the previous post and all has been great. 
  • edited December 2016
    This is not the problem here. Once this has happened, no adjustment of available sliders will make the distortion better. It's as if something gets out of sync within DAX. Only stopping and restarting the DAX stream clears it up.
  • DrTeethDrTeeth Member ✭✭
    edited August 2016
    Same here. Not seen it for a while but will recall the DAX tip for the next time.
  • PatrickPatrick WH6HI Member ✭✭
    edited June 2
    I used to see the distortion as in the pictures you have presented. But all changed when I loaded the newest version of 1.4.  I am wondering, and this is just a question.  Did the newest version of DAX get loaded and are you using it?  Just a question and I apologize if I am wrong.  Check and see if the 1.4 version of DAX is running. I am sure that already has been checked. 
  • edited December 2016
    The version of DAX running is identical to the version of Power SDR that is running (

    I think I see this less than I did with 1.3.8, however my operating habits have not been consistent (I was operating digital much more frequently then than I am now).
  • PatrickPatrick WH6HI Member ✭✭
    edited June 2016
    OK on your versions, does pay to check as I had 1.3 DAX SW come up instead of DAX 1.4.  Saw it right away and fixed it.  Don't know how it happened and could find no explanation for that situation other than op error when I cleaned up and deleted the wrong version.  In Version 1.3  DAX there was distortions and found that my ability to copy signals with DM780 was much reduced.  When 1.4 came out DAX became remarkably clean and I could copy almost all signals, even those close to the noise floor.  On JT65 and 9 The IMD noise was bad with 1.3 on signals above -12 db. and again 1.4 cured that. 
  • richrich Member
    edited March 2016

    I have this problem also with both V 1.4, 1.4.3 and earlier versions.  Happens rarely, often after switching modes/bands.  I have been forced to turn off the 6300, then turn back on.

    73, Rich, K3VAT

  • GM4WCEGM4WCE Member
    edited May 2015
    I also have seen this problem, although infrequently.  I restart DAX and it clears.
    Peter GM4WCE
  • K1DBOK1DBO Member ✭✭
    edited February 2018
    ...and I thought it was just me.
  • edited December 2018
    Unfortunately I started suffering the dreaded distorted rx audio via DAX on all 8 channels. It would occur randomly and restarting SDR and/or DAX only temporarily resolved it, it would return again at very random times - which resulted in wsjt-x not decoding and the audio containing pops.
    I noted via task manager that SmartSDR would occasionally turn red, indicating that the program had momentarily stopped? So...I connected my 6700 (signature series) directly to my pc via the ethernet cable but alas the problem returned. But...the next step resolved it permanently:- by starting up each copy of wsjt-x individually x 8, then starting up Smart SDR, and then (the most important part), turning on each DAX channel one at a time. This process of starting up each day has been faultless.
    My pc is a quad core I7 32mb of ram and SSD. 
    On a side note, I previously un-installed/reinstalled all SDR software, including signed DAX drivers a few times without any improvement.

    Looks like it was a Denial Of Service issue?

    Gary VK8AW / VK4ABW
  • WX4FWX4F Member
    edited January 2019
    Gary, this procedure still working well? I’m at wits end with mine the past week and very frustrating with failures mid QSO becoming quite frequent every 30 minutes. Will try it!!
  • Ed StallmanEd Stallman Member ✭✭
    edited January 2019
    I'm reading this at an aperture Time , Had a complaint last night on 80m FT8. I do keep the power and ALC low so now I'll keep an eye on TX signal and recycle DAX if needed 

  • edited January 2019
    Yes, it is still working fine. I have played around a bit more and found that you can start Smart SDR 1st if you want, and then all copies of wsjt-x but....don't enable any of the DAX channels until all your programs are running. I currently run eleven (11) copies of wsjt-x without any issues....using several radios. I allow a few seconds between enabling each of the 8 DAX channels, to ensure that they are working.
    The audio failures were quite evident whilst trying out Slice Master....which I deleted from my PC due to the horrible things that Slice Master does to your decoding programs configurations.

    This method works fine every day for my setup and I do change my configurations between HF / VHF bands regularly.
    VK8AW / VK4ABW
  • K1DBOK1DBO Member ✭✭
    edited January 2019

    I'd really appreciate if you could describe the problems you had with Slice Master.  I cant make it better without feedback.

    Slice Master doesnt change your WSJT-X configuration at all unless you ask it to.  Normally, it just copies your default WSJT-X configuration into a slice specific "--rig-name" folder of your choice, then works only with that.  Even then, the only setting changes it makes are those that are needed to run it with the slice you have chosen.  Worst case, you have to change your "rig", com port, and audio device settings.

    If your experience was any different than this, a description of the trouble you had could save one of our fellow Flexers a bit of trouble. Feel free to drop me an email.


  • edited January 2019
    Hello Don,

    Please don't get me wrong as I believe your program is a fantastic idea. I spent time playing around with the way it works but unfortunately the end results were not dependable.

    1. the placement of 3rd party programs on the display is not consistent. They would invariably end up in random spots, which then requires time to move.

    2. the configuration of port settings, PTT, additional frequency bands and tailored receiver bandwidths is over written every time it loads. I modified your program but the changes did not take. Flexibility in settings is required.

    3. Slice Master loads all 3rd party programs at once (if set that way). My feedback above details some of the issues this causes eg: corrupt DAX audio after random time frames which results in no decodes or total failure of the audio steams. Random failures of single audio steams occurs as well, which I could not pin down. Please also see my feedback as my method of loading 3rd party programs before allocating DAX assignments has resulted in ZERO audio failures to date.

    4. Slice Master does not always remember mode settings for WSJT-X V2.0.0. I have seen it load JT65 instead of FT8, despite changing the mode back and reloading again. Is this a save issue or clearing of old cached data?

    5. Slice Master will not load if Smart SDR is loaded 1st. Why would this be?

    The issue of corrupt / degrading DAX channels may or may not be directly linked or associated to your program, but I did notice an extremely high incidence of audio issues whilst using via a LAN. Bypassing the LAN lowered the rate of incidence.

    Something to think about Don....an option to change call sign SPOTS to abbreviated country allocations (displayed)?  As amateurs, many of us focus on chasing new / rare countries. This is why PSK reporter is so heavily used by the community, outweighing the current  'eye candy' of hundreds of call signs on Slice Master and trying to pick out that rare one. It takes time for the brain to process what is being displayed during pileups...Food for thought?

    I have provided my feedback via this medium as you may find other users with similar problems or suggestions and that is worth sharing.

    VK8AW / VK4ABW
  • K1DBOK1DBO Member ✭✭
    edited January 2019

    Thanks for the very thoughtful write up of your issues.  It's exactly the kind of feedback I was hoping for.  

    I suspect that your issues 1, 2, and 4 are all really the same problem.  As you know, each instance of WSJT-X needs its own configuration folder where it will write logs, decodes, and setting information.  When Slice Master launches an instance of WSJT-X it uses the 'Settings' option from the WSJT-X section of the Launch tab for each slice.  This option is passed to WSJT-X as the --rig-name option.  If two (or more) slices all try to use the same folder I can imagine results like what you are seeing.

    The placement of the instance on the screen is entirely up to the application.  Slice Master doesnt attempt any changes in this area. But, if one instance writes it's window position to another instance's setting folder.  Things will get mess up.  Same goes for other settings, like FT8 vs JT65.

    The whole 'Settings' idea in Slice Master has led to a bit of confusion.  Originally, I felt it would be useful to let the user choose the settings for a slice... as in this time let's use the FT8 settings on slice B and the JT65 settings on slice A, or vice versa.  In practice though I think hiding the settings option under an advanced nerd knob might be less trouble.  That way, slice A would always launch with Slice A settings, and slice B would always launch with Slice B settings.

    Issue 3 is a timing problem.  Most of the programs Slice Master launches have trouble if multiple instances are launched at the same time.  Slice Master does implement a "launch delay" that holds off a few seconds before launching the next instance.  Because different computers are loaded differently, the amount of time needed between launches can vary greatly.  For quite a while now the delay used to launch CW Skimmer instances has been user settable.  CW Skimmer is particularly sensitive to timings at launch time.  Yours is the first I've heard of trouble like this with WSJT-X.  The next release will allow the delays for all programs to be set by the user. With a bit a fiddling, an optimal delay can be found. 

    Issue 5 is simply a bug.  I usually have SSDR running when I do my testing.  Slice Master isnt of much use when it's not.  But you are right.  There no reason at why Slice Master shouldnt just sit there quietly waiting for slices to be created.
    My current development version has this one covered.  Fixing was a necessary part of getting the radio selector to function properly for folks with more than one radio.

    Regarding your spots suggestion... I like it.  Call signs are interesting, but might not be the first thing you'd like to cue on.

    Depending on the logger you are using you might be able to keep the clutter down already.  Slice Master doesnt do any filtering itself.  It relies on your logger to do it for you.  Currently this works best with both Logger32 and DXLab's Spot Collector.  Both are able to receive spots from Slice Master then send back only the spots that are not filtered out.  They provide coloring for the spots too.  Slice Master is also able to get color information from N1MM+ and HRD Logbook.  But filtering is not available from either. 

    Internally Slice Master scores each spot with a priority based on the "needed status" from the logger.  With N1MM+ this relates mostly to a spot's value in the contest.  I've considered adding some filtering based on this score but the feature hasnt worked its way to the top of the top of the to-do list yet.

    If my guesses about what's not working for you are off the mark (and you're interested in working through them) send me an email with a zip of your Slice Master config folder.  Navigate to

        C:Users<your user name>AppDataLocalK1DBO

    then right-click on 'slice-master' and select 'Send toCompressed (zipped) folder'.  This will create a zip file that you can then attach to your next email reply.  There's plenty of log information in there that might help to identify the issues.

    Thanks again for your comments.


  • edited January 2019
    Hello again Don,

    Thank you for the update. I do run up to 11 instances of wsjt-x at a time hence my raising the placement concern. I hope I haven't come across as too strong with my comments. I will endeavor to work through your suggestions as time permits. i really do hope that you take up for spots to be displayed as the country prefix in lieu of call signs in the overlay. I believe this will reduce screen clutter and allow amateurs to pick out entities much quicker.

    Individual settings for multiple instances of wsjt-x would be great. I prefer to run below the 3k bandwidth on some bands due to atmospheric noise, birdies etc. This improves the spectrum scope/ waterfall ability to pick out weaker signals which you can then focus on by moving the slice receiver to peak on them. This was very evident during our mid-year 50 MHz opening to EU. FT8 / JT65 is opening new doors every day on 6mtrs!

    I currently use 2 x 55" HD displays due to the amount of programs running.....Flex 6700, Ic7851, 756pro etc so it does get hectic with organisation. Hence some of the issues I raised would not apply to someone running single instances of wsjt-x or fewer slice receivers.


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