[amsat-bb] Re: AO-51 SIGNAL?
Alan P. Biddle
APBIDDLE at UNITED.NET
Mon Oct 13 08:04:16 PDT 2008
Speaking generally, satellites are not symmetric, often but not always
locked to the Earth's magnetic field lines, and everything from the gain to
the circularity depends on "how you look at it." The antenna may be
partially blocked, and far off axis a circularly polarized system becomes
elliptical, and may even reverse direction.
I have enough RX gain that it is never a problem hearing AO-51, but I do
notice there is some variation, particularly WRT polarization. Likewise, I
can always uplink on Mode-L, but there is a distinct difference in the power
required depending on the direction of the pass.
You mentioned both a beam and a vertical. More details would help to
determine whether you are "doing anything wrong," but it sounds as if your
gain is low enough that you are hearing the difference a few db makes. The
usual questions would be length and quality of coax, pointing accuracy for
the beams, use of a low noise preamp, etc.
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