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20M JT65 possible pirate

Discussion in 'General Announcements' started by N4AY, Aug 1, 2013.

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  1. N6YG

    N6YG Ham Member QRZ Page

    Bill thank you for your input and explanation.. I actually pulled up the documentation for the JT65 protocol to help refresh my memory a bit... As I recall there was a controversy regarding the legitimacy of qso's decoded via the deep decode algorithm..

    For those of you interested in further reading on the subject heres a start
    http://physics.princeton.edu/pulsar/K1JT/K1JT_eme2006_2.pdf

    I agree I worked about 700 JT65 contacts last month which means I probably decoded several 1000 JT65 transmissions and only saw 2 decodes that I confirmed were false. Both times the pass band was filled wall to wall with signals with quite a few of them being high power over modulated highly distorted signals. I'm sure this creates harmonics with phantom tones that intermingle with other tones creating false decodes..

    Anyhow once again thanks for clarifying the deep search decoder for us..
     
  2. N9DSJ

    N9DSJ Ham Member QRZ Page

    My pleasure.

    "controversy regarding the legitimacy of qso's decoded via the deep decode algorithm" is an understatement :)

    Mostly I was trying to convey the difference between "phantom" decodes due to the deep search algorithm and the jumbled/corrupt decodes that, on occasion, happen with JT65x modes using WSJT, Multipsk or JT65-HF. Some of this can be discerned by looking at binning information using raw decoder data when using software that supports such viewing. But, as you suggest, this is an anomaly and one gets used to discarding such abnormal decodes.

    73,

    Bill N9DSJ
     
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