Generally all very true! Except for when it isn't. :-) One of the things you
can depend on about 6m -- probably the only thing, actually -- is that it will
fool you. I've experienced 6m sporadic-E openings when signals were very
strong and rock-solid for hours on end, and coming in from multiple azimuths.
All this means is that there are many sporadic-E clouds, they are very hot,
they are very large, and they aren't moving very fast. :-) All "unusual"
characteristics for sporadic-E, by the book, yet there are many such openings
every summer across North America and Europe.
In the doctor business, it's called differential diagnosis. It's basically a
process of elimination, and it's never 100% certain. Basically, though, if
you're hearing signals from well beyond ground wave distance, and you KNOW it
isn't F2 because the F2 MUF is way below 50 MHz (as it is now), and it's not
aurora (no flutter/distortion, and/or you live too far south to EVER hear
aurora), and it's not meteor scatter (signals are stable for more than a
second or two), and it's not troposcatter (signal is originating from more
than 350 or so miles away and are strong) or tropoducting (unusual on 6m, but
happens) or D-layer ionoscatter (don't even ask), and it's during a period of
the year where you would expect sporadic-E (May-August, November-January) --
then it's probably some flavor of sporadic-E: single-hop,
multi-hop/earthbounce, multi-hop/extended-path, or some combination.
Sporadic-E propagation even combines with other modes: sporadic-E plus
meteor-scatter, sporadic-E plus tropoducting, and sporadic-E plus F2 have all
been observed on multiple occasions. During solar maxima (wait three or four
years from now), it is not uncommon to have F2 and sporadic-E propagation
happening at the same time -- sometimes combining on a path, sometimes acting
separately.
And sometimes, you are just very hard-pressed to come up with ANY plausible
propagation model to explain what you just heard/worked. Yet, there it is.
You gotta love this band. :-)
Bill W5WVO
Simon Brown (HB9DRV) wrote:
Volatile signal levels - can be there for a few seconds to a few
minutes or even an hour. Signals you receive come more-or-less from
roughly a single direction (N, S, E, W).
A big advantage of the bandscope on the IC-7800 / IC-7700 - you
suddenly see the band coming to life.
Simon Brown, HB9DRV
--------------------------------------------------
From: "Richard Davis" <[EMAIL PROTECTED]>
What are the characteristics of signals on 6 meters that are
propagated by sporadic-E? How would I recognize that s-E is in
effect?
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