[amsat-bb] FoxTelem changed?

[Burns Fisher]

So first, to answer your question, afaik, there has been no change in the
satellite downlink.

My "catch" also varies, but it usually depends on the orbit and the timing
(lots fewer people on in the middle of the night, and thus less time that
the transmitter is on).

However, you said that your eye does not seem to "lock up" despite a strong
signal.  Does that mean that you see a big "bump" on the frequency (FFT)
display, but you do not see an eye?  Or you see an eye but no new frames?

If you don't see an eye, I might suspect that the frequency is off.  Either
your SDR's local oscillator has changed a bit or if you are using "FoxTelem
Calculates Doppler" your keps are getting way out of date.  They should be
updated regularly, but you never know.  It should also not be all that
fussy with FM satellites, but again...YNNK.

If you do see a good eye, watch at the bottom.  You will see light numbers
that say "errors" and "erasures".  At least you will see them on the frames
that you get.  It would be interesting to know how high those are.  For a
good strong signal, it should be in the single digits.  If it is a bigger
number, that is probably one level of explanation.

Also, how high is the noise floor and the peak signal on your FFT display?
Too high can be as bad as too low.  You might play with your preamp (if
any) and the LNA and Mixer Gain within the FunCubeDongle (check boxes on
the "input' page of FoxTelem)

Good luck and 73,

Burns WB1FJ

On Thu, Jun 11, 2020 at 2:25 PM Mark L. Hammond via AMSAT-BB <
amsat-bb at amsat.org> wrote:

> Hi Mark,
>
> Glad you're collecting frames!  I haven't really seen a drop lately-at
> least I haven't noticed.   There is variability, usually due to changes in
> times of the pass (e.g., is the transmitter even on at very odd hours in
> the night?), and sometimes they can share a footprint, so you typically get
> frames from one but not the other.  So frames can vary.
>
> I have from time to time seen that a restart of Foxtelem is necessary;  I
> don't do it daily, but close...not sure if the decoder just needs a restart
> from time to time, or what.  It's pretty stable and consistent, for sure.
> I just do it more often than necessary so I can keep a watch on daily frame
> rates (basically resetting the counter...)
>
> You can watch what others are getting framewise here (thanks to spiffy
> coding by Chris AC2CZ!)    A bit of clicking and you get an idea of
> daily/weekly/monthly frames captured.
>
> http://www.amsat.org/tlm/leaderboard.php?id=0&db=FOXDB
>
> Hope it clears up for you.  Not sure this was any help, but I tried ;)
>
> 73,
>
> Mark L. Hammond [N8MH]
> AMSAT Director and Command Station
>
> On Thu, Jun 11, 2020 at 1:27 PM Mark Johns, K0JM via AMSAT-BB <
> amsat-bb at amsat.org> wrote:
>
> > For weeks I have been successfully capturing 30-60 telemetry frames per
> > pass on AO-91 and AO-92 with FoxTelem v.1.08z5.
> >
> > But suddenly, over the past week or two, I'm lucky to capture 10-20
> frames
> > in a pass -- sometimes as few as 1 or 2 frames for a 25 degree elevation
> > pass! The eye just doesn't seem to want to lock up, even when the
> downlink
> > signal is very strong.
> >
> > Nothing has changed in my station. Is something different with the DUV
> > signals of the satellites, or with the program, or some screwy Windows
> > update, or something else that I'm missing? Anyone else seeing the same?
> > --
> > Mark D. Johns, KØJM
> > AMSAT Ambassador & News Service Editor
> > Brooklyn Park, MN USA   EN35hd
> > -----------------------------------------------
> > "Heaven goes by favor; if it went by merit,
> >    you would stay out and your dog would go in."
> >     ---Mark Twain
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>
> --
> _______________________________________________
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