I'm specifically thinking of handheld linear antennas; I'm pretty sure you can rotate the RX antenna pol for "maximum smoke" and then the TX antenna faster than the tumbling rate of the satellite just to get an idea of which path is being affected.
This is a moot point though, most of us use Arrow antennas anyway!
On Tue, Mar 27, 2018 at 8:54 PM, Stefan Wagener wageners@gmail.com wrote:
Hi Sterling,
That would assume you have the ability to switch between linear uplink polarization (vertical and horizontal) and circular polarisation for uplink (right and left) and keep you downlink polarization on the same optimized path all the time, meaning you know in advance which way the downlink signal is the best to compensate for any uplink discrepancies. Good luck :-)
But hanks, good thought!
Stefan, VE4NSA
On Tue, Mar 27, 2018 at 8:47 PM, Sterling Coffey kawfey@gmail.com wrote:
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. > > 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@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) > > > > > > _______________________________________________ > > Sent via AMSAT-BB@amsat.org. AMSAT-NA makes this open forum
available
> > to all interested persons worldwide without requiring membership. > Opinions expressed > > are solely those of the author, and do not reflect the official
views
of > AMSAT-NA. > > Not an AMSAT-NA member? Join now to support the amateur satellite > program! > > Subscription settings: http://www.amsat.org/mailman/l
istinfo/amsat-bb
> _______________________________________________ > Sent via AMSAT-BB@amsat.org. AMSAT-NA makes this open forum
available
> to all interested persons worldwide without requiring membership. Opinions > expressed > are solely those of the author, and do not reflect the official
views of
> AMSAT-NA. > Not an AMSAT-NA member? Join now to support the amateur satellite program! > Subscription settings: http://www.amsat.org/mailman/l
istinfo/amsat-bb
> _______________________________________________ Sent via AMSAT-BB@amsat.org. AMSAT-NA makes this open forum
available
to all interested persons worldwide without requiring membership.
Opinions
expressed are solely those of the author, and do not reflect the official
views of
AMSAT-NA. Not an AMSAT-NA member? Join now to support the amateur satellite
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Sent via AMSAT-BB@amsat.org. AMSAT-NA makes this open forum available to all interested persons worldwide without requiring membership. Opinions expressed are solely those of the author, and do not reflect the official views of AMSAT-NA. Not an AMSAT-NA member? Join now to support the amateur satellite program! Subscription settings: http://www.amsat.org/mailman/listinfo/amsat-bb