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Thursday, September 11, 2014

Shortwave Echo Mystery on Yet Another SW Station. What is this?

A few weeks ago I noticed a strange echo on Radio China International's signal.  If you scroll down a bit you can see my YouTube recording of the problem.  On one of the SWL lists, there was speculation that this problem was the result of a flaw in the RCI digital studio gear.  But then a few days ago I heard it again on RCI -- surely the tech-savvy Chinese would not have let this kind of problem persist for weeks.  

Today I heard the same effect on a very different SW station -- this one an the 24/7 fire and brimstone broadcast that appears at many points on the dial.  The effect is very similar to what I heard on RCI.  

So OK all your shortwave gurus:  What is going on here?

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  1. Multipath propagation?


    73, Jan OM2ATC

  2. May be as simple as a studio technician listening to the air monitor with a mic open. Broadcasts today get significant delay as they are sent over the internet from studio to transmitter. Yesterday WLRN-FM was 7-1/2 seconds behind.

    Chip Veres
    WLRN FM & TV

  3. Maybe they just wound their cassette tape too tightly?

  4. To use a descriptive adjective from the late '60s and early '70s: trippy.

    You are right about long path not being logical, as the delay is about half a second. Such a long delay would imply several trips around the Earth (about 40000 kms in circumference).


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