Observed frequencies during auroras ?

Discussion in 'Radio Propagation Questions' started by G0FTD, Jul 29, 2017.

  1. G0FTD

    G0FTD New Member

    Greetings all.

    During an auroral event a couple of weeks ago several of us were radiating stable carriers on 28Mhz, and using Argo software
    to visually monitor the received audio frequency.

    Apart from the usual heavy doppler, over a 10 minute period we were able to observe a slowly decreasing frequency, almost
    like the transmitters were drifting slowly DOWNWARDS by about 2Hz.

    (Our transmitters / receivers are GPS locked and stable)

    I'm just wondering what the mechanism is for this ?

    73 de Andy G0FTD
  2. G3NYK

    G3NYK New Member

    Hi Andy I think you are displaying a "radar" trace of the movement of the auroral curtain. I think as the precipitation decreases the curtain drifts north. I think the frequecy shift you are seeing is due to the rate-of-change of phase as the total path lengthens. I have reports of similar (smaller) shifts at LF frquencies (136KHz) where North American stations have been using GPs locked transmitters and receivers for many years now to dig out very weak signals.
    Alan
    G3NYK

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