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Author Topic: Long delayed echo  (Read 615 times)

Offline GrahamC

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Long delayed echo
« on: July 28, 2018, 1443 UTC »
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




« Last Edit: July 28, 2018, 1451 UTC by GrahamC »

Offline ChrisSmolinski

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Re: Long delayed echo
« Reply #1 on: July 28, 2018, 1635 UTC »
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  :)
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Online TheRelayStation

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Re: Long delayed echo
« Reply #2 on: July 28, 2018, 1948 UTC »
that sounds to be about 500mS delay in my experience.
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Offline Josh

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Re: Long delayed echo
« Reply #3 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.
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Re: Long delayed echo
« Reply #4 on: July 28, 2018, 2129 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.
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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Offline GrahamC

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Re: Long delayed echo
« Reply #5 on: July 28, 2018, 2236 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.
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.


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



Offline Strange Beacons

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Re: Long delayed echo
« Reply #6 on: July 29, 2018, 1743 UTC »
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

Offline Pigmeat

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Re: Long delayed echo
« Reply #7 on: July 31, 2018, 1111 UTC »
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".

Offline Josh

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Re: Long delayed echo
« Reply #8 on: July 31, 2018, 1726 UTC »
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
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Offline Strange Beacons

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Re: Long delayed echo
« Reply #9 on: July 31, 2018, 2200 UTC »
The above all sound legit to me except for the TV station.

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.

Offline Pigmeat

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Re: Long delayed echo
« Reply #10 on: August 01, 2018, 1010 UTC »
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

I had buddy with a penchant for cheap used cars and knockoff Rolex's. One night he couldn't get his '74 Datsun to turn over, the thing was pushing 20 years of hard use. He lifts the hood and is tinkering around. I'm holding the flashlight for him and the guy next door is cranking it every time he shouts for him to. He's tinkering around with the ignition system & before I can warn him, the metal band on that ten buck Rolex comes too close to the metal distributor cap in mid-crank. A thin blue arc shoots up, his head flies into the hood, and the hood falls on top of him knocking him senseless. It was a true Kodak moment.

I saw him a couple of days later, he was still a little wobbly. He still has no memory of what had happened. A little Japanese car DIY shock treatment.

Offline MDK2

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Re: Long delayed echo
« Reply #11 on: August 02, 2018, 0154 UTC »
I had buddy with a penchant for cheap used cars and knockoff Rolex's. One night he couldn't get his '74 Datsun to turn over, the thing was pushing 20 years of hard use. He lifts the hood and is tinkering around. I'm holding the flashlight for him and the guy next door is cranking it every time he shouts for him to. He's tinkering around with the ignition system & before I can warn him, the metal band on that ten buck Rolex comes too close to the metal distributor cap in mid-crank. A thin blue arc shoots up, his head flies into the hood, and the hood falls on top of him knocking him senseless. It was a true Kodak moment.

I saw him a couple of days later, he was still a little wobbly. He still has no memory of what had happened. A little Japanese car DIY shock treatment.

Imagine the views you'd get if that happened in the smart phone / youtube era.
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Offline Pigmeat

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Re: Long delayed echo
« Reply #12 on: August 02, 2018, 1538 UTC »
I've actually thought about that over the years, MDK. That guy was a walking accident waiting to happen.