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). ----- 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 -- View this message in context: http://elecraft.365791.n2.nabble.com/LDEs-Long-Delayed-Echos-tp7610884p7610886.html Sent from the Elecraft mailing list archive at Nabble.com. ______________________________________________________________ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:[email protected] This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html Message delivered to [email protected]
