[CQ-Contest] On Echos and LDEs

[Heino Jukka]

There are at least four plus one explanations to the echoes:

1. Back Scattering. When you send a signal it may echo (bounce back). Echo
is about .1 secs or less. It is reasonable to expect that if you get an
echo, then conditions for getting a qso to that direction is possible (if
there are someone ready, HI). Some kind of "condition radar". Used much at
higher HF and VHF; needs fast transmit-to-receive switch, fast AGC,
reasonable power (and directional antennas).

2a. Around-the-world, qso with other station. Signal goes around the globe.
Delay about 1/7 secs. Very easy if you and your companion has at least
reasonable power and at least a small yagi. Back in 1970's I tried this with
ex-OH8OS, and almost every three or four day it succeeded (in summer at 14
MHz). OH8OS had a 1 kW to multi yagi pointing east, I used 100 W into 4 el.
pointing west.

2b. Around-the-world, own echo. Possibly needs both around-the-world and
back scattering (wave travels first around the world, goes "past you", then
back scatters). May also come direct from your antenna's back if the
front-to-back ratio is low enough. Anyway delay is about 1/7 secs. Quite
easy to catch. - Special case: Several times around the world. Wave is
trapped in ionosphere, goes several times around the world, then to the
antenna (docking). Delays then multiples of 1/7 secs.

3. Real LDE, delays in seconds, even 30 secs have been reported. Cannot be
explained easily; "slow waves", trapping in ionosphere or in van Allen belt
are ones among many others. These are the phenomena I'm interested in. UFOs?
Extraterrestrials? Some very old civilizations (at Amazonas or Tibet) and
their "time capsules"? Who says for sure?

4. Hoax. Always a threat. Remember that even Nobel Prize winners have
thumbeled their scientific results (our only winner, A. I. Virtanen, has
been reported to do that). May always be present!

Jim OH8OB

> ----------
> Jukka Heino
> www.oh8ob.net
> Any simple problem can be made insoluble if enough meetings are held to
> discuss it. (Mitchell's Law of Committees)
> 


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