Technical Topics > Propagation

Long delayed echo

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GC:

--- Quote from: TheRelayStation on July 28, 2018, 2129 UTC ---
--- 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.

--- End quote ---


bingo!  these two comments are right on the mark.


I made a post to the UDXF groups.io list and got some very interesting replies. One knowledgeable individual had all the details and our own Chris S made a comment which provided some additional collaborative evidence.


quote


Well, after some analysis by others on another list, it turns out that I mistaken in my observation that what I heard was a delayed echo.
 
 <quote - my reply on first and another post below>
 I checked the most recent Industry Canada frequency list and you are correct - Iqaluit and Cambridge Bay are still listed as remote TX sites on that frequency (listed as TX 11.2804 MHz which makes it a bit of challenge to search for). And Chris S estimation of "a delay of about 46,500 miles"  all fits as well.
 
So, what I heard was in fact more an interesting bit of propagation where I was clearing hearing both Gander and either their remote transmitter in Iqaluit or Cambridge Bay and the remote transmission had a delay due to relay through a geosat.
 
Not what I thought but still pretty interesting non the less.
cheers, Graham near Ottawa Canada
 
 
 
On 2018-07-28 16:45, wrote:
  <blockquote> At last check (when I retired from ATC electronics in Canada in mid-2016) Gander had the NAT-D family of frequencies at Cambridge Bay, Iqaluit and if memory serves at Gander NL. The two remote locations are fed via satellite links, and the satellites in geosynchronous orbit are about 22500 miles up so your round-trip calculation of 46000 miles is very accurate. A delay of half a second would not be unreasonable when multiple sites are selected for transmit at QX IFSS. Also, and this may have changed since, the feed to/from YQX actually went to North Bay Ontario then to Telesat for uplinking as Arctic Radio was always at YYB FIC until it was amalgamated into QX IFSS nearly 10 years ago, so additional delay can certainly exist in that process. As to why you heard the echo clearly then it faded may be more to do with changing conditions preventing you from hearing multiple sites continuously. Cheers<end quote></blockquote>And as I said - an interesting bit of propagation  but not what I at first thought it was.

cheers, Graham

Strange Beacons:
Interesting thread and thanks for posting the sound file.

Coincidentally, I have been doing some reading up on Long Delayed Echoes (LDE) lately. Here are links to a few interesting articles that I found:

Radio Ghosts Have Haunted the Airwaves for Nearly a Century

The Five Most Likely Explanations for Long Delayed Echoes

Was a broadcast by Houston's KLEE-TV picked up in England three years after the station had gone off the air?

Curt/W9SPY

Pigmeat:
The above all sound legit to me except for the TV station.

However the Granddaddy of them all, and the most persistent of these tales might be people claiming to have heard the distress signals of the "Titanic" decades after the fact. I first read about it in magazines like "Fate"when I was a kid and then in the supermarket tabloids well into the 90's, the tale occasionally making it into ham radio mags.

IMO, it's either an urban legend or a ladder hoax perpetrated by bored cw ops who read the original stories when they started in the 1920's. You read the story, think "Hmm..., that could be fun." and start sending. Every time the story was reprinted, including new reports of the "Titanic" being heard, some ornery op or three gives it a try and it starts again.

Any of you guys know CW? It could be time to raise the "Titanic".

Josh:
To do a Titanic call you first have to have a spark gap system up and running, the more powerful it is the better. No cw on Titanic, it was all spark gap. This is how it's done in the modern era;
https://www.youtube.com/watch?v=LbAcPl95PHU

Strange Beacons:

--- Quote from: Pigmeat on July 31, 2018, 1111 UTC ---The above all sound legit to me except for the TV station.

--- End quote ---

The link to the story that discusses the TV station is from Snopes.com. They debunked the story. Apparently, it was part of a fraud scheme that ended up becoming an urban legend.

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