Frequency hopper - 10680 to 10780KHz

G8JNJG8JNJ
in Signals Received
Hi All,

Frequency hopper heard between 10680 to 10780KHz here in the UK mid afternoon.

Stations from Indonesia were also quite strong around the same frequencies so it could be from some distance away.

Any ideas ?

image

Regards,

Martin - G8JNJ

Comments

  • WA2ZKDWA2ZKD
    Is that all of it? What was the occupied B/W?

  • G8JNJG8JNJ
    edited December 2017
    Hi Jim,

    Yes that was all of it, it was fairly well confined to a 100KHz wide chunk of spectrum.

    There were at least two stations transmitting in turn (one was weaker than the other) with different length transmit periods, usually lasting from 2 to 20 seconds  So I think it could have been voice traffic. The screen grab was of one of the longest transmit periods.

    Notice how some hops are clustered together at fairly regular intervals, maybe it's just a coincidence, as would be the case with a true random sequence. But I did wonder if these could be sync periods or is it something else like an aliasing issue associated with the waterfall sample rate ?

    The horizontal red dots are not associated with the hopper, it's an ionosonde sweep which can be seen passing through that chunk of spectrum.

    Regards,

    Martin - G8JNJ 
  • WA2ZKDWA2ZKD
    You might be able to caclulate the hop rate from the dwell time (?)

  • G8JNJG8JNJ
    Hi Jim,

    Maybe, but I think the waterfall sample rate is aliasing with the actual hop rate so I don't know if what I'm seeing is a true representation of the time spent on each frequency.

    It's a bit like the hoppers I can see on UHF Satcom around 243.75MHz.

    Regards,

    Martin - G8JNJ
  • WA2ZKDWA2ZKD
    HAVE QUICK in VHF

  • G8JNJG8JNJ
    Hi Jim,

    OK thanks.

    Regards,

    Martin - G8JNJ
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