received signals delay between "analog"_RX vs KIWI_SDR vs SDR_IQ_RFSpace

HI, put 0\zero delay for receiving on  a normal analogic RX the delay on the RFSpace SDR_IQ is +-100ms and +-1 to 1.5 sec on the KIWI_SDR.
For the SWLs that is not much important, but in the HAM world it is very important, it is makes the difference to complete a qso or not.
The latency factor on digital receivers is important, well known digital TRXs are in the range of +-10ms or less.
Is there any possible speed improvement in the KIWI software for the audio conversion?

ps sdr_iq values are for a lan server\client use, via USB are somewhat shorter.


  • The audio delay (lag) is a consequence of delivering buffered web audio over the Internet. WebSDR is better in this regard due to the advanced techniques they use. It is possible we might match them sometime in the future but it would take a lot of work. Their current method is proprietary.

    The KiwiSDR is not designed to be a ham radio QSO receiver with associated performance. It is a "shortwave receiver" class device with limited specifications from use of a 14-bit ADC, relatively low ADC clock frequency, lack of a better RF front-end, no direct IQ output etc. But it is designed to be self-contained, Internet enabled, multi-user and relatively inexpensive given its capabilities. A lot of this is explained in our design document, which is now somewhat out-of-date:

  • Can KiwiSDR be used with the software different from OpenWebRX? I have recently made some lag measurements on OpenWebRX OH2EAT receiver that is not using KiwiSDR. The audio delay was 3 seconds plus. The similar experiments with Kherson  OpenWebRX receivers gave even higher numbers. 
  • The delay in the KiwiSDR can be used to advantage in Ham radio. For example when I was in San Diego I could listen on Frequency with the KiwiSDR while transmitting from San Diego and about 1.5 seconds later I would hear my echo from the KiwiSDR at home. I would clearly hear how my audio sounded 1600 Km away. Listening to the KiwiSDR with an earpiece in one ear and listening to the local receiver with an earpiece in the other ear, I found the delayed audio useful in hearing stations not present locally but at the KiwiSDR, and with appropriate volume adjustment I found the delayed diversity reception to be quite useful. It did not take long for me to adapt to the echo effect. If you were a net control station, you could use strategically located KiwiSDR receivers to hear stations reporting to the net that you might not otherwise hear and realize if they were hearing you even though you were not hearing them locally.
    Ron - KA7U
  • NET DXing is a wrong practice and we're not going to use it. Talking about KiwiSDR in terms of remote RX site, since noise level in the cities is too high for an efficient ham radio activity.

  • HI Ron, your idea of one RX per ear was in my mind already from many years.
    Same feature as on my FT1000mkV_FIELD with its two radios.
    I have to add it to my audio switcher.
    For now I have a manual switch with which I listen from TRX_radio or from SDR_PC_audio.
    That is useful for a sort of diversity reception as you mention when the SDR is in a remote location free of noise.
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