[amsat-bb] AO-92 fading

[Burns Fisher]

If you have seen a model or picture of the Fox satellites, you may have
noticed that some of the solar panels seem to be mounted off-center.  This
is intentional so that photons that reflect off the shiny side give it a
tiny off-center push that spins the bird to distribute the heat more
evenly.  Thus it spins faster the more time it spends in the sun.  In
addition, when it crosses the equator, it should flip over (-Z and +Z
reverse sides).  This is because of the passive magnetic stabilization.
But I'm guessing that since it is spinning, that causes it to wobble.

Why 92 seems worse I don't know--I can only assume it has something to do
with the orbit.  That graph that Paul posted looks very different from
AO-85, for example.

Some RF person can correct me, but I believe that the 70cm antenna only
uses the antenna that sticks out one side, while the 2m antenna actually
uses the antennas on both sides.  Could that explain why the uplink has
more fading than the downlink?  I don't know.  Something to think about.

73,

Burns WB1FJ
Fox-1 Flight Software

On Tue, Mar 27, 2018 at 2:12 PM, Paul Stoetzer <n8hm at arrl.net> wrote:

> All of the Fox-1 satellites seem to spin faster or slower depending on
> orbit illumination or other factors.
>
> For example, this is the +Z panel rotation on AO-92 since launch.
>
> https://imgur.com/a/uS8TB
>
> Someone more well-versed in these matters can comment further on what
> causes this, but it is definitely not an indication of the health
> status of the satellite.
>
> 73,
>
> Paul, N8HM
>
> On Tue, Mar 27, 2018 at 1:59 PM, Jean Marc Momple
> <jean.marc.momple at gmail.com> wrote:
> > Dear All,
> >
> > I have been experimenting with AO-92 as from its launch. Some
> observations:
> >
> > 1) The fading on this bird seems to be high and quite unpredictable,
> requires a lot of changes of polarization  to keep the Rx signal to an
> adequate level.
> >
> > 2) Seems that the fading is both on the U/V and L-mode, more seems to me
> that the uplink is more affected.
> >
> > 3) Telemetry seems to be quite reliable with FoxTelem in all modes.
> >
> > Today, it was even worse losing the bird many times during the pass, it
> seems that it is degrading quite quickly, hope that this is not the case.
> >
> > Just to share my observation.
> >
> > 73
> >
> >
> > Jean Marc (3B8du)
> >
> >
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