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Re: Contacts on AO-10

on 2/13/00 11:33 AM, MarkG at markg@pptnet.com wrote:

> Around 5:30 UTC (early) this morning I worked W7DU, he in Washington and me
> in Pennsylvania. His signal was good, around a 579, when the bird wasn't in
> a deep fade.  The fading is a bit of a pain, but QSO's are still very doable
> if you talk fast and have a little patience to wait for the fade to subside
> which takes severals seconds to perhaps a minute. I believe the bird came
> into range around 5:00 UTC here, which is FN10. There's also a pass at
> around 16:00 UTC which works pretty well, having worked LU4EBC today with a
> 56 SSB signal, but that's a daylight pass, of course. The fading was still
> very evident. I guess the bird is tumbling so that the top or bottom of the
> bird faces the sun now and then, killing power for the duration. You don't
> get a lot of notice as within a couple seconds, a signal will FM, drop in
> frequency and then disappear. Stay put and it'll return in a few seconds to
> where it was, give or take a bit for the usual doppler effect.

AO-10's fading is not necessarily predictable and the reason you don't hear
a signal might not be because it is in eclipse.

We haven't done it in a while, but Mike, KF4FDJ and I have had regular QSOs
during early morning passes of AO-10 and these have been quite good.
Additionally, during the right passes, Europe and Asia can easily be worked.

Here are some things I have learned and that others have taught me as well:

1.) The polarization of the signal sometimes changes quite rapidly.  This
applies to both uplink and downlink.  According to Mike, KF4FDJ, as the
satellite wobbles, it ends up messing with the polarization of the signals
or what the antenna sees.  So as the bird tumbles, the polarization switches
due to the position of the antennas.  If you have antennas that can be
switched, this is good.  If not, you may be assuming the bird is not
workable because either your downlink or uplink signal or both are in
completely opposite polarizations from what you need.  I have seen this many
times myself.

2.) The fades are not necessarily due to lack of sunlight but also position
of the antennas due to the wobbles.  There was a pass into Europe about a
month ago that I remember well.  When I could hear myself well on the bird,
I was very weak into Europe.  Then it would switch and the bird would fade
for me and be open towards Europe.  As the bird tumbles, it seems the
antennas are pointing in different directions so you might not be in the
maximum portion of the antenna's beamwidth at any given time.

3.) Just cause it is dark where you are doesn't mean it is dark where AO-10
is.  I assumed this was the case for a while and missed many a good contact.
Even if AO-10 is traveling over portions of the earth that are in shadow, it
may still be in bright sunlight.  Most of the Europeans I have worked have
been about 11 at night here in Chicago when the bird is out over the
Atlantic.  It was dark on the ocean under the bird but the bird was in

Fades on AO-10 are like QSB on HF except more severe.  With a little
patience you can work through them.  I would also like to put one more guess
as to how you can tell the fade is due to an eclipse or due to some of the
phenomena I mentioned above.  Right before an eclipse as the bird begins to
move into shadow, you will hear the frequency change.  Then the bird dies.
When it comes back on again when it gets light, you will hear the same
effect.  If the fade is NOT due to a sunlight eclipse, you won't hear the
FMing of the frequency.

Just my thoughts.  AO-10 is a blast!



Jon Ogden



"A life lived in fear is a life half lived."

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