Echo?

[boater sam]

Has anyone experienced a station in the middle of the medium wave that has an echo with the broadcast about a quarter of a second behind? 
I have a Blue Peter which is fine on all stations but this particular one, sounds really weird. Is it an image?

[Mike Watterson]

An IF image would be in sync on an Analogue receiver. A delay in the signal path or signal processing of the transmitter is possible.

Also a ground wave vs sky wave reception will have a delay on the sky wave.

[Kalee20]

It would have to be a huge distance though, 1/4 second is 46,500 miles difference in path length, nearly twice around the world!

[Mike Watterson]

Ionosphere is high up.

Also a satellite link adds about that much delay for a one way link. Not unusual for satellite to backup a terrestrial link or be the only feed to some sites.

[boater sam]

I was alerted long ago the the time delays between AM, FM, and DAB transmissions. This was somewhat similar but more akin to an echo as the repeat was lower in volume. Its not there today!

[Pye Man]

Another transmitter of the same programme out of sync that good conditions meant you could hear? A lot of the commercials who have taken over old ILRs for pseudo-national programming have not been that bothered as MW/AM is dying and has few listeners. Often they are or were only hanging on to the frequencies to keep some sort of foothold in an area due to Ofcom rules. (With FM and DAB now ubiquitous, never mind streaming, some (like Bauer) are handing their licences in early and taking the Ofcom fine as no doubt this is cheaper than running the Txs.)

[boater sam]

Two transmitters is the obvious thought but would I notice the time difference in the transmissions?
What causes the time difference between DAB and analogue transmissions?
They would have to be very far apart at the speed of light.
They were both terrestrial signals! The Martians don't have Medium wave!

Perhaps it was just a bizarre freak, or tape print through on a recorded  station output?  It was both music and speech.

Sam.

[Refugee]

The time difference between DAB and FM is due to the audio having to pass through a rack full of digital stuff before transmission and again more digital stuff in the receiver.
The FM signal is transmitted direct and has no delay.

[DrStrangelove]

This has reminded me of the 1930s long delayed echoes phenomenon.

http://www.arp75.org/wp-content/uploads/...090318.pdf

As far as I'm aware, it's never really been explained.

Though I'm quite sure that the Ancient Aliens Researchers so beloved of the Blaze channel could come up with a theory or two.

[radioman]

I heard a station on short wave three years ago with a long echo - you can hear it on my Youtube video here :- https://www.youtube.com/watch?v=ex23MV_vPNQ
I can't remember what the station was but I checked it at the time and they only had one transmitter on that frequency.
There was some solar activity at the time and I just assumed it was going multiple times around the earth before I picked it up.

Andy