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Long delayed echo

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GC:
Early Saturday morning is one of those times I find that I have a bit of quite time that I can spend "spinning the knobs" of my radio.

Around 11:00 UTC (7:00 EDT) I was scanning through 11MHz and came upon a signal that at first I thought was HFGCS on 11175kHz but was not on that frequency.

I thought of HFGCS (i.e. MAINSAIL) due to the "echo" noted on the audio.

However the frequency was 11279kHz and was Gander Radio with an echo of about one quarter of a second (wild guess). At first only Gander Radio was effected and the aircraft transmissions were not. After a short while the echo on Gander Radio's transmissions diminished only to return again for a while and I could hear this same echo on at least one of the transmissions from one of the aircraft but missed which one. This effect did not last that long was effectively gone by about 11:30 UTC.

I attempted to listen to Gander on a couple of the online Kiwi SDR's but was not quick enough - I didn't hear Gander at all on some or only weakly on others.

I managed to make a short recording - about 1:15 in length (14mb in size), I have posted it here:

https://www.dropbox.com/sh/ix7wo4xgai7xvze/AAAmvMfvBes-Ylk1N2p5gWk1a?dl=0

for anyone who might like to have a listen.

The first part of the recording shows a very clear and distinct echo. About a half minute later it is almost completely gone. Unfortunately I did not get a recording of the aircraft's transmission having the same sort of echo.

I have heard echo's and delays before but this one is the clearest and most distinct that I can recall.

Some consider long delayed echoes to be those of greater than a couple of seconds while others have a much looser definition. A quick search using Google or your preferred search engine will find much food for thought.


cheers, G near Ottawa Canada

ChrisSmolinski:
Very interesting! It's difficult to tell exactly how long the echo is. A quarter second implies a delay of about 46,500 miles. I am not sure what could cause that, I have read of speculations of ionized clouds of gas some distance from the Earth. If the delay is really much less, say half that or an eighth of a second, then the delay is about that of the circumference of the Earth - and what you would expect from hearing long path along with the direct shorter path (I think you are very close to Gander?)

I recall hearing a delay of a few seconds many many years ago when listening to Radio Canada International. From memory, it was several seconds long. Not sure I have heard it any other times. It seems to be one of those things you cannot directly search for, you just have to get lucky  :)

TheRelayStation:
that sounds to be about 500mS delay in my experience.

Josh:
When you hear hfgcs echo, it's more likely due to several tx sites simulkeying around the world than an actual long delayed echo. Not that it can't happen tho.

TheRelayStation:

--- Quote from: Josh on July 28, 2018, 1954 UTC ---When you hear hfgcs echo, it's more likely due to several tx sites simulkeying around the world than an actual long delayed echo. Not that it can't happen tho.

--- End quote ---
that was my first thought also, that Gander may use a second TX located in another area for coverage reasons, there are many HF communication stations that do this.

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