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DAX RX 1.6.17 Audio Crackling

Bob N7ZO
Bob N7ZO Member ✭✭
edited May 2020 in SmartSDR for Windows

I have
been running SSDR 1.5.1 successfully on a Windows 7 desktop computer (Core i7, wired Ethernet, etc.).

Since I upgraded to 1.6.17, I have been having intermittent crackling on my DAX RX channels.  This is audible when listening to the audio (selecting “listen to this device” on the Sound control panel) and visible as energy outside the expected bandpass spectrum on the FLDigi waterfall and other audio programs.  The DAX RX audio is bad enough that my digital decoding is very poor.  Audio directly from the radio and from “Remote” is fine.

Here is an image of mild crackling as viewed on FLDigi when the radio is in RTTY mode with 500 Hz bandwidth.  Note the blue to the left and right of the main bandpass. It gets worse.


I downgraded to 1.5.1 and the crackling has gone away.

Has anyone else seen this?  If I am alone, I will try some more troubleshooting after K5P and the VP8’s are QRT.

Note that the DPC latency checker looks very good and I followed full un-install and reboot procedures when upgrading to 1.6.17.

73, Bob, N7ZO


  • Ian1
    Ian1 Member ✭✭
    edited May 2020
    Havent seen this and have used it on digital modes often
  • Tim - W4TME
    Tim - W4TME Administrator, FlexRadio Employee admin
    edited March 2017
    Since you have downgraded, not much we can do.  I recommend that if you have this issue you try one of two things.  Reboot the PC to see if the issue is on the client side of the connection.  If that does not resolve the issue, power cycle the radio to see if the issue is on the radio side of the connection.  If neither of those fixes the issue, I would then look at the network connection.
  • Rob Fissel
    Rob Fissel Member
    edited January 2016
    Thought I'd add to perhaps follow Tim's guide to doing a complete uninstall of 1.5 prior to 1.6. Not sure if you did that before originally installing 1.6, but there are major changes to sound card devices, and starting with as clean of a slate as possible might be a good idea. 
  • Bob N7ZO
    Bob N7ZO Member ✭✭
    edited March 2017
    An update:

    In order to use the Maestro without the upgrading and downgrading (running 1.5.1 on my PC), last week I upgraded the PC to SSDR 1.7.30.  I am happy to report I have so far not encountered the DAX 'crackling' I reported (see the first post in this thread) occasionally with 1.5.1 and consistently with 1.6.

    I have been reading the release notes and there is nothing to indicate DAX had been changed since 1.6 (which is why I have not upgraded until now).

    Tim, or anyone in the know, can you comment on what might have changed in DAX?  I do not think there were any changes on my PC that could account for this.  I'd like to have some confidence that this was a deliberate and durable change.

    73, Bob, N7ZO
  • Tim - W4TME
    Tim - W4TME Administrator, FlexRadio Employee admin
    edited December 2016
    DAX and CAT were completely refactored in SmartSDR v1.6
  • Bob N7ZO
    Bob N7ZO Member ✭✭
    edited December 2016
    Hi Tim,

    Yes, I know that.  That's what made my problems worse and started this whole thread.  :-)

    The question is what was changed between 1.6 and 1.7 that reduced (maybe eliminated) the crackling?

    73, Bob, N7ZO
  • EA8DIG
    EA8DIG Member ✭✭

    I have a new 6600 line. The clcks are very annoying, happening every 15-50s, at odd intervals on RX, and always when changing the TX focus or/and coming from TX to RX or when a message pops up in the lower right screen....

    Can this issue be resolved ? It makes the FDX feature unusable as the clicks are effectively interfering with RX and hearing them for ours will drive me crazy.

    W11, gaming I9 laptop, 32GB ram, running solely for the Flex...


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