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  • Flatness of KiwiSDR response < 500 kHz?

    Do you overlap windows?

    Not at the lower zoom levels because the waterfall/spectrum sampling is not continuous (the decimation factor is low and the sampling period is only a fraction of the display line time). This of course changes radically above zoom level 10 and I have to overlap when the sampling period exceeds the time it takes to display a line (the decimation factor is huge at that point). It took me forever to understand this because I didn't know what I was doing (some would say that has not changed, lol) and don't really have sufficient mathematical/DSP background.


    Re Glenn's observations and experiments with CM and ground loops: I've been meaning to return to the topic and try and understand the issue in detail because Glenn is obviously a tremendous resource and understands a very important issue. But it needs a good chunk of time which I currently don't have.

    The whole situation is confusing to me because of some anecdotal evidence. I don't deny it. I believe in CM. But I don't understand why some Ethernet-based installations have dead quiet noise floors and others are worse than useless. A lot of these quiet installations have photos of their setups in the Kiwi splash screen and they seem to be the typical jumble of equipment in a box with an Ethernet switch, SMPS, cables and other stuff all thrown together. And yet they work great!

    What's the difference? Is there a minimization of the Ethernet/antenna cable loop by chance? Something subtle about the ground wiring/isolation? I don't get it. And I wish I did, because then I could make a recommendation to people.

  • Flatness of KiwiSDR response < 500 kHz?

    Are you using a window ahead of the FFT?

    It's using a Hanning window now. And the code has the usual suspects available (but commented out): Hamming, Blackman-Harris. I haven't look at the windowing specifically in years. Although we had the recent problems I induced when changing the FFT pixel downsampling and adding CIC filter compensation.

  • Waterfall issue [Android app issue fixed in v1.460]

    If you're talking about the KiwiSDR Android app, then yes, there was a problem that was just fixed. Kiwis that run the latest release (v1.460) or later should work with the app again. About 70% of public Kiwis have updated. The rest should follow in the next day or so.

    The issue was that the app uses an embedded web viewer that did not fully implement web standards that the Kiwi code depends on.

  • v1.456,458,459

    @HB9TMC I'll fix that today. Shouldn't be applying the CIC compensation when there is no CIC in use! 🙄

    As for the spectrograms, I don't know. All the Kiwi spectrums I looked at using the Kiwi spectrum display and high averaging gave the same peak values on a variety of settings. I guess the only thing to do is make a new waterfall API option so you can select either behavior and Marco can get his fix for SuperSDR.

  • v1.456,458,459

    v1.457,458 May 21, 2021

      Waterfall / spectrum:

        Fixed low-level post-FFT artifacts spotted by Marco's SuperSDR app. Thanks Marco!

        Added CIC filter compensation to better level spectrum at top end.


      FAX extension:

        Added GM-11F Sevastopol 7090.9 kHz per fabrys on Kiwi forum. Thanks fabrys!