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Friday, September 19, 2014

Long Delayed Echo on Radio China International

Several people have e-mailed me suggesting that the weird echo I have been hearing on shortwave broadcast stations is in fact one of the fabled "Long Delayed Echoes" that radio amateurs have been hearing intermittently since about 1927.   I was skeptical at first, but -- at least in the case of the Radio China signal -- I think LDE caused by the signal going around the globe several times does explain what I've heard.  Each trip would add a delay of about .133 seconds, and that seems to match what we hear in my recording: 

Compare that with what K9FIK recorded on 10 meter SSB (thanks Stephen!):
(you can listen to the audio on this one). 

It sounds very similar. 

If this is in fact LDE, I'm lucky -- this is pretty rare.   And it is a eerie that I first heard it on on Regen receiver from the 1920s!  Above is a picture of the regen used to study the FIRST LDEs. See:

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  1. Well, you always USED to say in jest that "regens are possessed." Perhaps this is not a LDE, but more a phenomenon worthy of Art Bell's show of yore, that is to say, for wont of a better expression: an actual case of Regen Possession.

    The audio files and pix you put up are fascinating, nonetheless.

    OT: you may know about and enjoy BBC 4 radio's "In Our Time", hosted by Melvyn Bragg. Quite lightweight, but pleasant bus/train listening. The podcasts on RElativity 06-vi-13 and The Invention of Radio 04-vii-13 are worth listening to, however light.

    Going to listen to thE K9FIK 10m SSB file again. It's...trippy 73 desde Guadalajara, JAL

  2. Thanks, Bill. I found a link to some articles on LDE at

    David WA1LBP


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