24 Hour waterfall capture

Hi All,

Yesterday I caught the tail end of a massive solar burst, which raised the noise floor on one of my KiWi's by 20 to 30dB over the spectrum from 5MHz to greater than 30MHz, for a period of 10 seconds or so.


Space Weather Message Code: ALTTP4

Serial Number: 609

Issue Time: 2023 Jul 16 1531 UTC

ALERT: Type IV Radio Emission

Begin Time: 2023 Jul 16 1509 UTC

NOAA Space Weather Scale descriptions can be found at


Description: Type IV emissions occur in association with major eruptions on the sun and are typically associated with strong coronal mass ejections and solar radiation storms.


It made quite a spectacular pattern on the waterfall as it shifted in frequency, but in my haste I managed to overwrite the screen grab I took :-(

I also looked on the University of Twente web sdr, which has a series of 24 hour captures.


But it didn't seem to have sufficient resolution or sensitivity to have caught the event.

PD4P's recent initiative to snapshot every KiWi got me wondering.

Does anyone have a method of obtaining very long duration waterfalls from a KiWi, similar to the Twente web sdr ?

I found this previous discussion,


But ideally I'd like to capture 24 hours at a time

I had thought about taking periodic screen grabs and stitching them together, but I'm sure there must be a better way.

I think we may have covered this before, but my memory has let me down and I can't seem to find anything else using the forum search function.




  • There is a function export_waterfall(). It records the waterfall in a jpg file. This function can be called periodically after a certain time. This way the waterfall will be saved automatically. For example

    setInterval(export_waterfall, 60000);

    will save the waterfall every minute.

    Just open your kiwi and paste it into the browser console.

  • Hi,

    I just tried this but I get an error message ReferenceError: export_waterfall is not defined

    However using the method as defined in the previous thread, I did manage to grab this solar burst event earlier today.



  • edited July 2023

    Martin, I tested it on the original KiwiSDR and on the non-original. Everything works and I don't get any errors.

    I realized your mistake. Use the browser console (F12 or ctrl+shif+j) and not the ssh console.

  • It was the Firefox browser console I used.

    However it worked in Chrome.



  • I check in Firefox. It works )))

  • Hmm, that's strange.

    Any ideas why it says export waterfall is not defined as the error message ?



  • edited July 2023

    Maybe the FireFox console has some additional security settings that don't allow functions to run or something like that?

    Try to type just:


    And it seems to me that you have some other console))

    Press F12 and chose "Console" in the top bar, like on my screeshot.

  • OK I originally used ctrl+shift+j , but that does bring up a different console in Firefox.

    F12 works just fine.

    Note that you do have to permit automatic and multiple downloads in the browser config for it to work correctly.



  • I was glad to help!

  • One slight problem, and this one is for John.

    I've been using the waterfall time stamp function. Which has generally been OK.

    However if I use the very slow waterfall speed of 1Hz, the time stamps are very erratic. Sometimes they are present, sometimes not, or they will show up for a while in clusters, and then disappear again.

    But if I speed up the waterfall they reappear again.

    I'm wondering if this is related to the waterfall speed, the point at which the waterfall is written, and the point in time when the time stamp is applied are somehow not quite being in sync with each other ?



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