locked Re: Being called when just monitoring and not transmitting


Bill Somerville
 

On 16/12/2020 15:51, David Gould wrote:
I run WSJT-X (2.2.2) and JTAlert (2.16.15).  Recently I have spent quite a lot of time just monitoring 15m, and never transmitting.  I have noticed several times that I get called by a "station" with the right format  eg      "G3UEG  IO6YIP BG06           a2"

How can this happen?  IO6YIP is not on QRZ.COM so is suspect.  How is my callsign known, I have NOT transmitted at all , not even tuned up.

This has happened probably 6/8 times over the last couple of months.  Sometimes the message format is obviously gibberish, but sometimes nearly right as above.

I am perplexed!

73,
Dave  G3UEG
Hi Dave,

this happens because of AP decoding techniques, it is a false decode. In this case a priori decoding postulates that you might be being called as a result of calling CQ and, by assuming messages might be to you, it can increase sensitivity to messages where that information may be erased (missing) due to QSB or interference. Because the reduced number of bits being decoded, the false decode probability is slightly raised due to the smaller set of possible decodes. Check the WSJT-X User Guide for information on what the "a2" indicates:

https://physics.princeton.edu/pulsar/K1JT/wsjtx-doc/wsjtx-main-2.2.2.html#AP_Decoding

73
Bill
G4WJS.

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