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How to decode FSK signals using FSK Extension/Decoder - Not found on Forum search

Once the tone-bars are set on a FSK signals commonly found on 20-meters and going thru all the possible ITAC/ASCII/CIRC476 and 5Nv1--->end-of-selections
plus all BAUD selections, nothing ever decodes.

How is this done by others ? Please reply on this forum AND to in case I miss it on this forum

73 Dick/w7wkr


  • you might mention a freq./signal you tried
  • jksjks
    edited March 2019
    Yes, the FSK extension is frustrating to use. But that's partly because decoding FSK signals is frustrating unless you know most of the many transmission parameters involved. Otherwise the search space is too large. That's why the FSK extension has a number of example signals that you can tune (using a Kiwi in an appropriate location, mostly Europe). See the "Weather, Maritime, Military, Utility" menus.

    I don't know that much about ham use but I believe the old-time RTTY stuff is more likely to be 5N1 or 5N1.5 and ITA2 as the encoding. With some skill you can use the "scope" and "framing" functions from the mode menu, instead of "decode", to help narrow down the correct baud and framing values (just like the "baud error" indicator helps select the correct baud rate). Although these functions are not currently documented.

    [A bit later] Sure enough, I was able to tune some contest RTTY on 40m using a Kiwi in The Netherlands. As seen in the screenshot below I used shift=170, baud=45.45, framing=5N1.5, encoding=ITA2, not inverted. I found I couldn't get away with any other framing as you can sometimes do with real modem hardware, i.e. 5N1 and 5N2 didn't work. UZ2I calling CQ test:


  • v1.275 renamed the FSK extension Utility menu to "Ham / Utility" and now includes the 80m - 10m RTTY calling frequencies with 170/45.45/5N1.5/ITA2/no-invert presets.
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