Christoph's SDRA 2019 TDoA talk from Friedrichshafen is up on YouTube

edited July 2019 in TDoA topics


  • jksjks
    edited July 2019
    By the way, I disagree with the questioner at the end suggesting the Cyprus OTHR is located at Cape Greco and not DHFCS Akrotiri. I did some searching and found several convincing references that what's located at Cape Greco are two high-power (600 kW) MWBC transmitters for TRW and R. Sawa. The photos I found are certainly fixed towers in traditional MW directional configurations and not the broadband types (e.g. dipole arrays, curtains) needed for the observed frequency agility of HF OTHR. I did add Cape Greco to the TDoA reference station list. Maybe some good TDoA results can settle the matter.
    (switch map to "Bing satellite")

    TRW & R. Sawa listings at (look for first entry in list "CYP"):

    However, the comment that the OTHR receive site is relatively close to Cape Greco is correct I believe.
    I had spotted it here some time ago (three long receive arrays):,33.9017068,1455m/data=!3m1!1e3
  • Love it when someone makes a complicated process sounds like opening a can of beer.

    Other uses..
    I think the coastguard uses doppler shift direction detection on the emergency frequencies, would be interesting to have a few Kiwi's at set locations constantly buffering the IQ stream to (for example) Amazon storage so, on triggering, they could call a snapshot starting from say 15 minutes before the emergency call was recognised. Same for HF airband.
  • I too disagree with this comment. My response to it was unfortunate.
  • Alright, I got lucky with some TDoA results and have a new theory. What I thought was the receive site described above is actually the transmitter site (marked "OTHR/CYP2" on the TDoA map below). If you look at that Google map it shows three long element arrays each at roughly 30 degrees to each other (individual array elements are small white dots if you zoom in far enough). This structure is very similar to the JORN arrays seen at three locations in Australia.

    To me this makes some sense as this OTHR is very often heard transmitting on multiple frequencies simultaneously. If the beam steering of an individual array has limits then multiple arrays at different angles might be needed to cover the areas of interest.

    The Akrotiri site (marked as reference "OTHR/CYP1" on the TDoA map) is full of dozens of Yagis and other TX/RX capable antennas. Probably not the place you want a multi-megawatt ERP service co-located.


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