Direction of audio streams from different receivers to individual sound cards?

SM0AOMSM0AOM
in KiwiSDR Discussion
Hello,

I am intending to use the KiwiSDR for an aeronautical HF/SSB monitoring project.

In its present configuration, the audio streams from all receivers are superimposed on one sound-card channel.

This is impractical when monitoring many channels simultaneously, as the noise from the idle channels will deteriorate the SNR of the active channel.

Is there a way of separating the audio streams to separate sound-card channels?
It is intended to use a web browser running on a Linux platform.

A related question is if there is some way to implement an adjustable RF gain threshold, so the background noise can be suppressed somewhat?

Comments

  • G8JNJG8JNJ
    >
    >A related question is if there is some way to implement an adjustable RF gain threshold, so the background noise can be suppressed somewhat?
    >

    Yes it can be adjusted in the purple tabbed AGC section of the control panel.

    Regards,

    Martin - G8JNJ
  • WA2ZKDWA2ZKD
    edited February 2020
    It may take multiple instances of your browser and routing with something like jack or pavucontrol. Or at least that is where I would start
  • KA7UKA7U
    edited February 2020
    @SM0AOM ,
    For Linux I use Pulse Audio and Pavucontrol to manage audio streams.
    https://wiki.archlinux.org/index.php/PulseAudio
    https://wiki.archlinux.org/index.php/PulseAudio/Examples
    from the command line:
    man pulseaudio
    pacmd --help
    pactl --help

    Example window using Pavucontrol with Pulseaudio to direct audio streams from open tabs on a web browser.



    Ron
    KA7U
  • WA2ZKDWA2ZKD
    I wasn't sure it would do tabs...
  • WA2ZKDWA2ZKD
    https://unix.stackexchange.com/questions/174379/how-can-i-create-a-virtual-output-in-pulseaudio
  • ChrisSmolinskiChrisSmolinski
    I'll give my KiwiSDR Sound Client python script a shameless plug, it might be useful for your project?

    https://blackcatsystems.com/software/kiwiSdr-sound-client-virtual-audio-device.html
  • AB9ILAB9IL
    Here's another thumbs up for using PulseAudio / Pavucontrol. I will add a suggestion to create multiple loopbacks, which you can either set up in your Pulseaudio config files or via the command line.

    You can then feed a multitrack recorder or multiple soundcards.

    As to the receiver gains, I get good results by reducing the AGC threshold until the noise floor is down to -15 dB. For the slope, try 2 dB instead of 6 for a bit better sound. Otherwise, the background noise will drive you mad, and recordings will be far more noisy than they need to be.

    Some of the SDRs run with the gain way to high! Others don't, do definitely take the time to adjust each channel as necessary.

    Cheers,
    Phil AB9IL
  • cathalferriscathalferris
    For me Pulseaudio has always been a right pain for me in the past - completely unsurprising when one finds out who originally authored it (Poettering - the same idiot that "manages" the SystemD dogpile). It may have improved over the years, but it's been a steaming pile of brown when I've gone to configure it.

    I've learned the hard way to steer clear of PulseAudio. If it works for you, fantastic. Doesn't work right for me.
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