Loran C : More info

zachliangzachliang
edited June 2019 in Problems and Issues
OK i made a decoding with Loran C and seen he pictures
What can then i get from that ?

Comments

  • jksjks
    The image below shows valid Loran-C signals. The Kiwi is in Japan and the two chains in China and South Korea. The master stations consist of 8 pulses, a pause and then a ninth pulse. On the scale click to the left of the master station to manually align it with the "M" slot on the display left. Then the stations will be in their proper positions. Unfortunately many LC chains have been shutdown in the last decade including ones still in the extension menu.

    There isn't anything you can really do with the signals except verify that you are still hearing them. The timing resolution of the pulses present in the audio stream isn't sufficient to generate any navigation solutions. That would have to be done at a higher bandwidth in the Kiwi FPGA.

    image

    Attachments:
    https://forum.kiwisdr.com/uploads/Uploader/df/e495999e09190200d9e3964e0ec3d0.png
  • zachliangzachliang
    Thank you!
  • jksjks
    edited June 2019
    To see what chains are still active click on the link in the extension control panel "See also LoranView by DF6NM". Markus' site has run for years and hears every active LC chain worldwide from his location in Germany using specialized software he developed.
  • bensonbenson
    Hi Zachliang,

    A couple of years ago PA3FWM wrote a short article about Loran C operation (see ref 1). If you are still in reception range of an operating Loran-C chain either directly or via a remote Kiwi it shows you how to estimate your receiver's position. No doubt you will recognise the process for finding the position is similar to what is run during use of the Kiwi TDoA extension and takes place with just the push of a button.

    Since WW2 a lot of development effort has gone in creating a long series of hyperbolic navigation systems for maritime and aviation use.
    Systems such as Decca and Loran A used initially maps with hyperbolic grid overlays and left it to the navigator to periodically find the position from the indicated time delays. Later direct lat lon readings became possible and opened the way for waypoint navigation, coupling track guidance to autopilots and presenting progress on moving map displays.

    The advent of GNSS / GPS has made them largely obsolete or so it seems. Doubts remain whether in a global crisis situation these satellite systems will remain available and accurate as we take for granted nowadays. Perhaps one reason the Alpha VLF transmitters were kept alive so long after Omega shutdown.

    ref 1 : http://www.pa3fwm.nl/signals/loran-2015/

    Best regards, Ben.
  • zachliangzachliang
    Many thanks!
  • G8JNJG8JNJ
    Hi,

    It's difficult to tell exactly from your screen grab, but I suspect you are actually seeing and 'decoding' interference from a Switched Mode Power Supply instead of a genuine Loran transmission.

    Regards,

    Martin - G8JNJ
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