LONG DELAY ECHO REPORTS

Wish I had a recording, but we're talking about the fall of 1974. I remember, because I was still in high school. I've never forgotten the details, because it was so weird. Our 75 meter group was talking on 3915 KC about 7 PM. There were stations in ( west to east) Dallas, Paris and Longview Texas-Shreveport, Ruston and Monroe, Louisiana Vicksburg, Mississippi and one in Alabama (don't remember town). The effect started on the station furthest west, which was about 200 miles west of me.After transmitting, he'd let go of the PTT and you'd hear the last word or so repeated, like an "echo." The effect moved like a "front" from west to east, though there was no unusual weather at the time, and the delay got longer as it "moved" over my location in north Louisiana.

A strange aspect: the guy in Paris never heard it. The guy in Longview heard it weakly, but only for a short time. All of us in north Louisiana heard it, but it was strongest and longest over Shreveport.  It was as though it "echoed" only those signals coming from the east, back to the east. When the "front" passed over my location, I could key my mike, say a couple of short words, unkey and hear it repeated back to me with good signal strength.


Once the "front" passed over me, I couldn't hear it anymore, but the guys east of me did.  The effect continued east, fading in intensity and delay length until it finally stopped. The guy near Vicksburg was last to hear it.  He said it was weak and only repeated the last syllable, suddenly stopping entirely. Another oddity:  the guy in Alabama never heard it. The whole thing took about an hour, so whatever it was moved about 400 miles in an hour; no weather front could do that.

Never had a satisfactory explanation, nor have I heard it since. The delay was far too long for it to be troppo or some other weather related deal, nor could it be a "modulated magnetic flux line" ala the whistlers on longwave, because there is was no doppler shift. Easily the strangest thing I've ever heard on a radio.

73 Dave S.

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I once heard a similar thing.   But it was on 6 meter SSB. A station in 0 land was cqing contest.  Then for about 3 minutes I heard a 'echo' of his transmission....but it was higher in frequency.  Doppler?  I reported it...but was told it must have been a mechanical problem with his cq tape. Hard to believe since the signal was a good half strength of the original.

Dan/W4NTI

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From Nick G4FAL

What is really spooky is when you hear your own signal several seconds later.  That
is still unexplained so far as I know.  It happened to me once in the 60s late
at night on 20 meters and I have heard others describe the same.

This is correct.  I have also experienced this effect ... only once in
over 40 years on the air.  It happened at about 0915 UTC one winter
morning in 1966 on 21 MHz SSB, when I was operating the London Science
Museum station GB2SM.  The beam heading was just east of north (I
guess about 15 degrees) and the output power was 400 watts PEP.  The
band was open to VK and ZL via the short (polar) path.  I began to
observe echoes of my own signal at the end of each transmission,
delayed by just over a second and audible at good strength.  The delay
was long enough to say "Hello", allow the VOX to drop, the hear the
complete word "Hello" come back.  I tried sending single characters on
CW, with the same result.  There was no significant doppler shift of
frequency.  The effect persisted for about 3 or 4 minutes, then the
echoes quickly faded and disappeared.

A very strange effect.  The delay on the echoes was far too long to be
explained by a single round-the-world path.  (At about 1.25 seconds,
it was almost half the delay typical of earth-moon-earth echoes over a
480,000 mile round-trip path!)  I have always believed the signal
somehow got trapped between two ionospheric layers at high altitude
and experienced multiple reflections between the layers until
eventually being released after more than a second's delay.  However,
that theory remains unproven.  It seems to be a very rare phenomenon,
but has been witnessed and documented by several observers over the
years.