If linear polarized, if you can keep your RX/downlink antenna still and you can at least hear the satellite, and rotating your TX/uplink antenna results in correlated signal level changes on the RX/downlink, then you've isolated it to the uplink polarization variable.
On Tue, Mar 27, 2018 at 8:44 PM, Stefan Wagener wageners@gmail.com wrote:
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@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@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@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@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.
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@gmail.com wrote:
Dear All,
I have been experimenting with AO-92 as from its launch. Some
observations:
- 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.
- Seems that the fading is both on the U/V and L-mode, more seems
to
me
that the uplink is more affected.
- 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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