[amsat-bb] AO-92 fading

[Stefan Wagener]

Thanks,

Again, even in full duplex how do you distinguish between a non-matching
uplink vs non-matching downlink? You only "hear" the downlink!

73, Stefan VE4NSA

On Tue, Mar 27, 2018 at 8:38 PM, Sterling Coffey <kawfey at gmail.com> wrote:

> You can hear your own signal if you have a full duplex (two radio) setup.
> However, it's still pretty hard to tell if you use a single antenna (arrow,
> elk, etc) since you're changing the RX polarity while you're changing the
> TX polarity too.
>
> On Tue, Mar 27, 2018 at 7:22 PM, Stefan Wagener <wageners at gmail.com>
> wrote:
>
>> One of the questions I have is why one would think that the uplink
>> (polarization) is a problem since you only have the downlink to assess and
>> how would you differentiate between uplink "weakness" from downlink since
>> that is the only thing you hear. In addition, at least for uplink, you
>> could "in principle" very quickly adjust with higher power... and no, I am
>> NOT promoting crocodile behavior (big mouth little ears)
>>
>> Stefan, VE4NSA
>>
>> On Tue, Mar 27, 2018 at 2:26 PM, Burns Fisher <burns at fisher.cc> wrote:
>>
>> > 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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>> _______________________________________________
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>> Opinions expressed
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