On 11th November, Milt wrote...
"...The sets of mirrors are not the same ones in the two directions. The
difference in the arrival angles at the two terminals are different and vary
from minute to minute. The arrival angles are not identical at the two ends
most of the time indicating to me that the propagation between the two
terminals is not the same..."
*************************************
Hi Milt,
But doesn't what you've just said here simply harken back to what was
mentioned earlier about QSB (slow, or otherwise), and the reciprocal effect
it has upon the "quality" of copied signals...?
To whit: going back to Tom's mirror "experiment", as you raise one of the
top reflective mirrors up higher off the floor (or, as the active portion of
the ionosphere changes height above ground), the amount of reflected energy
from station "A" to station "B" will most likely have been severely degraded
(or, there will have been considerable QSB experienced by station "B")...
But...!
When station "B" commences its transmission to station "A", that same
elevated mirror / higher ionospheric surface will still be in an as high ---
and less-than-opportune position --- as it was when "A" transmitted to "B"
the first time...
Result: the amount of reflected energy being received by station "A" will
have been severely degraded, too (or, there will have been considerable QSB
experienced by station "A").
The solution --- if it might be called one! --- would be for EACH of the
lasers to simultaneously re-focus upon the re-adjusted / higher mirrors,
with the hope that the reflected energy might in turn reach the opposite
station with ample energy (or, if the received signal is coming in at, say,
a high angle, then a high-angle transmitting antenna should be utilized, in
turn)...
A hardly practical solution in the "real" world.
The old truism remains robust for 160: "...One can never have enough
antennas for Top Band"! The best any of us can do, I guess, is to erect
either the tallest of towers from which to hang our dipoles from, or to
design some multi-element vertical / inverted "L" array with a motherlode of
copper below...or preferably, both!
Then, when we pull out our hair for want of being unable to raise a peep out
of a stong station that we just KNOW we should be able to work, we can
simply blame it all on bad luck --- or, "...one-way propagation." :>)
~73~ Eddy VE3CUI - VE3XZ
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