RE: Regarding Time Signals

From: Walter Ridgewell (
Date: Mon Feb 23 2009 - 23:19:47 UTC

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    Hi Peter,
    The delay you describe is rare, but could be possible occasionally. Radio
    signals propagate by bouncing and bending thru various mediums, like the
    Ionosphere, Troposphere, Magnetosphere and so on. Typically the propagation
    time delays are quite small for 'terrestrial' signals.
    The frequencies you mention are for CHU (3.333) the Canadian time station
    and WWV and possibly WWVH (in Hawaii) the US time stations. WWVH is
    distinguishable by it's female announcing voice. Most of the time the HF
    propagation delay from the transmitter to the listener is in microseconds
    (25 - 175), and as such ignorable. Even  a multi hop or long-path
    propagation effect of circumnavigating the globe is a mere 138 milliseconds.
    Longer delays of up to 300 milliseconds have been reported via Magnetosphere
    ducting of paths longer than 1 earth radius.
    What you describe could have been an LDE or Long-delayed echo, which have
    been reported during sunspot minimums. In these events multiple echoes have
    been heard lasting up to 7 seconds or more, but these events are very rare
    an still not well understood. Therefore the use of radio/HF time signals
    should not be considered an accurate method of timing derivation.
    Walter Ridgewell,   I.S.P 
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