[Elecraft] LDEs (Long-Delayed Echos)

[Sverre Holm (LA3ZA)]

An 80m or 160m signal echo after about 1/7 second may seem like a
round-the-world echo. But it is more likely that it is a ducted signal in
the magnetosphere. The actual delay varies with geomagnetic latitude, and
the further south one is the closer the delay time is to 1/7 second.  

Such signals can be trapped in occasionally occurring, tubular
magnetospheric ducts, which stretch from the northern to the southern
hemispheres along the Earth's magnetic-field lines. 

I wrote about it in QST in 2009 -
http://folk.uio.no/sverre/papers/2009_MagnetoDucting-QST-LA3ZA.pdf.

There was also an excellent article about it in Radcom by P. Martinez
(G3PLX), "Long Delayed Echoes, A Study of Magnetospheric Duct Echoes
1997-2007," Radcom, Oct 2007, pp. 60-63 (not on the web to my knowledge).

I have an analysis of several such medium delayed echoes or
magnetospherically delayed echoes (MDE), including that of G3PLX, here:
http://la3za.blogspot.no/2010/03/magnetospherically-ducted-echo.html 

The echo time can be predicted from latitude, so if I get more data, I can
run my program to estimate the delay time for a given place at a certain
time (geomagnetic latitude rel to geographic latitude varies with time).








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Sverre, LA3ZA

K2 #2198, K3 #3391,
LA3ZA Blog: http://la3za.blogspot.com,
LA3ZA Unofficial Guide to K2 modifications: http://la3za.blogspot.com/p/la3za-unofficial-guide-to-elecraft-k2.html
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