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edited August 2017 in Signals Received
Does anyone else look at Ionosondes and Digisondes?


  • jksjks
    edited August 2017
    Very nice article from PA3FWM, creator of WebSDR:

  • seems like an extension for tracking one chirp TX could be possible (?)

  • Hi, I am looking at ionosondes, look interesting, but I can not if it should be possible to make the KiwiSDR do a GPS-time controlled sweep.

  • Hi,

    Some more information relating to previously used amateur methods for receiving Ionosondes here


    Martin - G8JNJ 
  • Indeed those slanted lines so well visible on the 30 Mhz wide Kiwi display are intriguing. The sweep rates, period and UTC offset of these chirp sounders can easily be determined visually.

    In addition to the IBP scan and WSPR extensions the ability to get live ionograms from the growing worldwide Kiwi network would be great to monitor propagation conditions.

    Seems the basic ingredients for a  chirp sounder receiver are already there in the KIiwi : UTC time reference,  GPS pps signal, ability to tune at fixed rates of 50, 100,125 or 500 Khz/sec either continuously or in steps starting at pre-determined offsets from 00:00 UTC.
    From the receiver audio signal the delay time and signal strength could then be derived and presented as an ionogram. Probably easier said then done though...

    Additional references:

  • edited April 2019
    WA2ZKD wrote: seems like an extension for tracking one chirp TX could be possible (?)

    I recently used some auxiliary programs to tune KiwiSDR (via Catsync) and tracking certain chirp sounders to see if propagation is open in parts of the HF spectrum. Even without using Chirpview these programs allow synchronising the Kiwi with the sounder visually by trial and error and although not giving precise propagation delays and signal strength still give a good impression which part of the spectrum is open towards a particular sounder. A short video recording is attached*.

    Identifying those sounders remains a challenge like in the Chirpview days since the period & chirp time tables that can be found are all quite dated. I tried to use TDoA during stepper operation but usually only few usable points on the dt chart show up. The internet time delays probably wreak havoc not giving enough settling time for the remote Kiwis to be tuned to the stepped frequency. For the GPS locked sounders however the distance (path length) can be easily found using Chirpview.

    Likewise using the audio chirps or beeps to create an ionogram from the sweeps would require a known time delay. For the TDoA project this was already determined. Generating ionograms might be possible on the Kiwi internally but internet connections show unpredictable and continuously changing delays. Using a PPS signal I measured 1.4 to 2.2 sec delays between Kiwi rx in and audio out using a PPS signal on a local network. As mentioned in the forum ionograms are already available from the large GIRO network showing the more modern DPS4D pulse sounders.

    Three different programs were used that can step tune a receiver to follow chirp sounders. One (ref 1) tunes via a COM port output but is limited to 100 kHz/sec sweep rates and a 300 sec periods only.

    The others I found (ref 2) are more flexible however tune either via a localhost or DDE interface via HRD (Ham Radio Deluxe). Still trying to figure out how to bypass HRD altogether and send the data directly to Catsync via a virtual COM port.

    These steppers are not ideal and would need some modification in terms of interfacing, currently used sweep rates and sounder periods. Alternatively a frequency stepper could be built from scratch.

    So who knows at some point if there is sufficient interest and after enough of the remaining chirp sounders are identified this could lead to a Kiwi extension where a particular sounder is identified via a drop down list.

    ref 1 :
    ref 2:

    Best regards, Ben

  • Christoph has been working with chirp sounders recently:
  • With the waterfall timestamping added in 1.462, it seems like some visual correlation could be made between time and when a sweep crosses a frequency. However, finding a list of active sounders and their start time is needed and I have not had good luck finding that info.

  • Unfortunately the bulk of ionospheric sounders these days seem to be digital.

    A list of stations can be found at

    The two linear CWsweeps that can be observed in Europe most days, I believe originate from the UK Military site in Cyprus.

    A GNU radio project is about the only Chirp related project I've seen in recent times.

    I was a member of the Chirps email list until the recent decision to close it due to lack of activity.

    If you wish, I can send an email to Peter Martinez, to enquire about the current status of active swept CW sounders.



  • Hi Martin,

    In SE Asia I still see quite a few traditional chirp sounders active. Although I can find the range to the GPS disciplined stations using Chirpview determining the location would require a Chirpview set-up at another location in the region. So if you can get hold of a recent list of these sounders that would be quite helpful.

    Best regards,


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