KiwiSDR TDoA Direction Finding now freely available

Discussion in 'Amateur Radio News' started by G4TUT, Jul 12, 2018.

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  1. G4TUT

    G4TUT Ham Member QRZ Page

    KiwiSDR TDoA Direction Finding now freely available

    An online network of KiwiSDR radios enables you to pinpoint the location of stations using Time Difference of Arrival (TDoA) direction finding techniques

    The RTL-SDR site has published an article about the online radios:

    The KiwiSDR is a US$299 HF SDR that can monitor the entire 0 - 30 MHz band at once. It is designed to be web-based and shared, meaning that the KiwiSDR owner, or anyone that they've given access, can tune and listen to it via a web browser over the internet.

    Many public KiwiSDRs can be found and browsed from the list at or by signal strength and location on this website

    Read the article at

    K9FV, K3LTC, K9EZ and 2 others like this.
  2. K4FMH

    K4FMH Premium Subscriber QRZ Page

    This is the approach that the ARRL should’ve taken with OO respin to reduce intentional HF QRMing. But they wouldn’t even respond to emails to make this suggestion.
    K0WJ, N7GPP, KK6QMS and 1 other person like this.
  3. WB8LBZ

    WB8LBZ XML Subscriber QRZ Page

    Flex Radio had the provision with it's 6700 to have a remote receiver. Now this idea has been improved with the KiwiSDR and the world wide distribution of receivers. Add to that TDOA and this is super. I have used this system for Texas state-wide networks on 40 and 75 and it really helps. Many thanks for those that put up a system.

    73, Larry WB8LBZ
    El Paso, TX
  4. K4FMH

    K4FMH Premium Subscriber QRZ Page


    Gerald Youngblood and I worked out a distributed system using special Flex SDR receivers to monitor all US HF bands 24x7 to cloud severs with direction finding. Appropriately appointed OOs could review those files for QRMers and other violations with reasonable determination of lat-lon location. This initial evidence can then be used to "watch" for the offending ham, record forensic evidence of the violations, and turn over the FCC enforcement. I'm told by Senate staffers who communicate in oversight capacity with the FCC that this is the labor shortage versus other priorities that the FCC Enforcement Bureau staff faces. It would greatly help them and help us through the ARRL's supposed new OO team strategy. But the League's committee chair never responded to my emails....President Roderick was briefed on this at the MFJ 45th Anniversary when I met with him. He never followed up either.
    KC0TA and K9FV like this.
  5. VK4GAP

    VK4GAP Ham Member QRZ Page

    Reading this is a coincidence , just the other night i was looking at one kiwi_sdr and web_sdr at a time around my area checking signal strengths to see if i could figure out where that noise is coming from .

    That noise = Wide Band 80M buzz /Machine at night here (VK4) , the other night it went for hours around 3635 +/- , i assume it's some type of Over The Horizon Radar , it's been around for years , every one blames Russia out here (vk) or China , the quick look around i took inferred somewhere else .

    The only trouble is some of those antennas are only whips and the likes and would be a bit deaf on 80M compared to some of the other antennas used on them .

    So , i'll check this posting topic out to see what is available now looking for the place/area of Origin of the wide-band 80M Buzz Saw sound .

    Attached is the 1st basic look about using kiwi-sdr and web-sdrs the other night .

    Tnx Paul .

    Attached Files:

    K4FMH, KB4QAA, K9FV and 2 others like this.
  6. K1MGY

    K1MGY Ham Member QRZ Page

    Another example of just how useless the ARRL has become.
    N7GPP, K4FMH and K9FV like this.
  7. VK4GAP

    VK4GAP Ham Member QRZ Page

    A update from above post >

    What a tease it all is , i can just barely here the Buzz on 3640KHz , so took a look about , the result was that the sdr on the North Island of New Zealand (ZL) was the only other one that could just barely hear it too , nowhere to be heard in Russia/China/ Indonesia , mid Pacific or India or anywhere else including VK6 , only 2 spots and in the noise .

    I'm aware that those Government Paid CB'rs can switch antenna directions as i have seen it happen and heard it in real time (believe it or not i can sit there listening to it for hours , i find it a soothing sound :) )

    I recollect 1 time someone must have accidentally switched over to mic audio? as i heard a few sounds (i don't recall the words but a cough is in the memory with another sound) , also i have seen signals immediately drop from S9+ to S1 with what sounded like a relay change-over (Antenna Direction?) .

    No where else but Here and ZL ? , is there a OTHR down there in Antarctic? , and low power tonight ? with a narrow beam .

    Anyway , i tried to get the OP's DF to work but could not figure it out so far (back on to he OP's topic) , i'll wait for some S9 sigs to turn up , i even tried to DF my SSTV sigs on 80M , the map just wont turn up after the 30 second or so calculation .

    tnx , Paul ..
  8. VK4GAP

    VK4GAP Ham Member QRZ Page

    Last update otherwise i'd fill the whole forum up .

    After watching MOTOGP came back to the radio and there it was again S9 , this time only all around here and ZL , weak in south china , non at Indonesia , weak in Japan and eastern Russia .

    Then tried the DF again and actually half red the help file this time , saw that the receivers had to be close together (which is a bit limited in vk) , did the thing and it came back with a graphic which suggests the origin is from antarctic from over? Tasmania yellow lines or is it the red line there? , the lines marked on the attached pic are not very clear but there is a wide reception direction there from south i think it says .

    Looked around via sdr's way up north to see if anything was heard up there but nothing (to see if it being propagated from over the other side over the top (unlikely though as it would be daylight) , so non the wiser at all not that anything could or would be done about it so really a moot point of interest .
    That is all , i'll be looking , Paul .
  9. AB8CL

    AB8CL Premium Subscriber QRZ Page

    Just gave it a try. Located WWV on 10.000. out of ft collins.
    KK6QMS likes this.
  10. VK4GAP

    VK4GAP Ham Member QRZ Page

    How do you read the result map ? Hi BTW , is the direction from yellow or red ?

    Have a listen here if it's not busy or pick another over this way to hear the buzz/saw machine 3635KHz (look on the map page) , if you could be bothered .

    Paul .
    Last edited: Jul 15, 2018

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