ANTENTOP- 02- 2010, # 014

Some Notes about LDE from G- QRP-C Forum

Date: 2 December 2010 17:44

Subject: [GQRP] Re: Long

delay echos

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<GQRP.yahoogroups.com>

I have always had a fascination

with the subject of LDE's and

also just

heard about this event.

I have heard very short echos before. However, this

past weekend during the contest on Saturday

evening I heard what I thought was a LDE in the

range of 2 to 4 seconds. It was on 40 meters and I

had just tuned in a station and it sounded like

whatever that station was sending was being

repeater that 2 to 4 seconds later. The echo

interfered with the original but was slightly off

frequency but even at that I didn't manage

to get the call sign. It was a German call sign but

not DK6NP that I recall.

I was otherwise distracted by the contest at the

time and didn't give it much more thought til today

when I stumbled some of the reports of Peter

Brogl's experience. Makes me wish I had paid more

attention.

Cheers, Graham ve3gtc

China Power Automobile Relay.

Inside View

Date: 3 December 2010 06:51

Subject: Re: [GQRP] Re: Long delay echos

Mailing list: <GQRP.yahoogroups.com>

I remember hearing echoes as a not

unusual occurrence back in my days as a

broadcast band SWL in the early 60s.

These were on AM commercial broadcast

stations, if I recall correctly, on the 49mtr

and 41mtr bands.

I was using an old EKCO valve domestic

receiver and I remember talking to my

'tame' local radio amateur who pooh-

poohed the whole idea based on "I haven't

heard them on my equipment so they

can't exist".

He was convinced I was wrong but I knew

what I had heard was real.

The echoes weren't terribly delayed,

maybe no more than 1 or 2 seconds

but the effect was reminiscent of the old

early tape loop echo chambers used in the

music business.

I seem to recall, though through the

distorting fog of age, reading about

this effect some years later suggesting

that it was similar to total internal

reflection in light travelling through a

refractive medium.

Now I suppose that if (and bear with my

somewhat hairbrain hypothesis here) a

radio wave got injected into the

atmosphere and then, due to some

abnormal atmospheric condition was

repeatedly bounced up and down

between two similar levels of refraction as

it travelled around the earth until it

emerged at a point of lower refractive

index, then that possibly might create the

effect observed.

Something similar is, as I understand, the

manner by which light is fed down fibre

optic cables without it emerging from the

sides.

Far fetched possibly but I just wonder......

Slim Haines G4IPZ

More about LDE and Strange phenomenon of the Propagation read at AntenTop Magazine:

http://www.antentop.org/book/c_LDE.htm

http://www.antentop.org/book/c_propagation.htm

www.antentop.org

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