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v1.419,423: added non-NBFM squelch

v1.419  November 8, 2020
    Added a simple RSSI-based squelch for the non-NBFM modes.
        See audio tab of control panel. Based on Christoph's squelch from kiwirecorder.
Don't expect too much from this squelch implementation. It's not a VAD or anything. On the audio tab move the squelch slider fully left to disable (default). Two squelch values are stored separately: one for NBFM and another for all other modes (except DRM which doesn't need it).

For the non-NBFM squelch the slider represents dB above the median of a number of past RSSI (S-meter) values. There is also a menu of "tail" times -- additional time the squelch is held open before being closed.

The speaker icon now has a third color, white, indicating the squelch is closed (hence no audio). This in addition to red (muted) and green (squelch open or disabled).


  • Really great option, thanks to you and Christoph.

    Would double upvote if I could.
  • Small correction: as far as I know the squelch feature in was implemented by its original author and not by me.
  • A big thank you for adding SSB Squelch. I feel that at a single stroke the value of the Kiwi network has increased dramatically. Being able to park a squelched rx on a net channel while tuning around on another slice is a real asset. Thanks again.
  • Great job with that lockout. I know there was already a thread asking for the ability to block IQ or Comp, but another nice option would be to have as default the Audio filters with std-wdsp-75us settings set by the administrator just like the default profile in waterfall.

  • The squelch is much appreciated here as well. Bonus on the selectable squelch tail, too! :)
  • jksjks
    edited November 2020
    @Christoph: Right you are. I see it now in Dmitry's original repo. I assumed it was your idea given its current class-object implementation.

    If you're looking for some strong periodic signals to test with: try the mil-com burst sigs around 4.03, 4.79 and 5.75 MHz (EU), HFDL air-com sigs, the ham band FT8 frequencies or SSB contest stations.
  • Squelch is a great addition, thanks for adding it! Testing it now on the CB band.
  • Nice feature, John. Thanks!
  • Just love the Squelch. Obviously you need a good S/N ratio for excellent results. Now a suggestion, is it possible to implement Squelch start/stop trigging of the sound recorder ?
  • That's one of the first things I thought of. The problem is I couldn't think of an obvious user interface solution. That is, should the built-in recorder always respect the squelch? If not, how would you indicate such an option? Where would it go? Nothing immediately came to mind that would fit in the existing UI and/or cause massive confusion.
  • The recorder could always respect the squelch. It is probably OK since the default is squelch wide-open. This would require someone to adjust the squelch (and thus know of its existence) for it to affect recording. A tooltip somewhere could be helpful as well.

    Just my 2 cents. Thanks for continuing to be active on development of this great product!

  • njcnjc
    edited November 2020
    For the non-NBFM squelch the slider represents dB above the median of a number of past RSSI (S-meter) values.

    Are the RSSI values used for the moving average from within the passband only? Couldn't this result in the threshold being too high when monitoring a strong, constant amplitude signal? It does not seem to behave this way. Indeed, it seems to work quite well!
  • Yes, I agree, the recorder always respecting the squelch is a reasonable solution. The squelch is working great on the CB band, it's very worthwhile addition, thanks again for adding it!
  • My 2 cents regarding UI. Could the speaker symbol to the right of the recorder button go red during Squelch recording and white/green as today on the other modes. In the "Audio" menu the "Scuelch" text could also go red with the recorder on ?. When i have the word. I have 4 KiwiSDR in use and what a wonderful experience this has been. My first KiwiSDR was indeed a very capable and interesting product, very early i became impressed and satisfied with the hardware and now many, many firmware updates later it still amazes me how dedicated John and his team always is. Many thank`s John for one of the most interesting and rewarding experiences in my 45 years as a Radio Amateur. And almost 40 years as a professional radio engineer. 73`s to you all.
  • jksjks
    edited November 2020

    Okay, v1.423 makes the record function respect the squelch. The record icon turns white and stops spinning when the squelch is open. It applies to all squelch modes including the original NBFM squelch.

  • That works, so well it seems like it has always been there.

    I'll use that for some elusive signals I've seen in the spectrum max hold.

    BTW Forum upgrade is welcome too,

  • edited November 2020

    It, of course, is good. But to users of an iOS with systems is higher, than the 14th version, is better to give old WebAudio API (old code for WebAudio API?). Now I experience some difficulties. For example, the «Comp» button has disappeared. Now I can't choose high quality audio. It started with version 1.419.

  • Not sure what you mean. The Kiwi uses Web Audio exclusively.

    The "comp" button is on the same line as the pan slider. But the pan slider is only shown if Web Audio says it has panning capability. This was necessary because some obscure browsers don't support panning (e.g. WebTV). It's a bug that the comp button disappears when the pan slider is absent. But the real question is why all of a sudden the pan capability is missing from iOS. This is true on my iPhone 5S and iPad 2. It's fine on Android. Another bug to chase..

  • Okay, v1.424 is out which fixes the issue. I had to go back in my notes, but it turns out iOS doesn't support audio panning either. So the only bug is that the comp button needs to be moved to the volume slider line when panning is not available. v1.424 does that.

  • Yes, everything is fine now. From version 14, audio panning works if you enable the Modern WebAudio API. For some reason it seemed to me that the problem was related to the iOS API.

  • jksjks
    edited November 2020

    The problem there is that my iDevices are so old I don't have that option. My iPad runs iOS 9 and Safari has none of the experimental options. My iPhone runs iOS 12 and has about half of them, but not "modern WebAudio API". 😐️

    But thank you for verify that is works with the latest iOS.

  • John, I also noticed that the "de-emp" function is not working correctly. 75us = 50us. There is no difference between them. I tested it on different receivers. Perhaps this problem is old. Because in version 1.402 this is also noticed. Checked in headphones. iOS system.

  • This is a very welcome addition. I'm spoiled by my Micom, Datron and other commercial HF radios with syllabic squelch. This function seemed to be in websdr(I run one of those as well) and now to me KiWi is in the same league. It may not be voice activated but it sure does work well. The settings I find work well are 8 dB and .2 seconds.

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