[amsat-bb] FoxTelemetry on AO-91 and AO-92

Wed Oct 3 22:44:48 UTC 2018

Hmm.  Interesting.  My experience has been that the voice over data has no
effect, and that, in fact, I'm more likely to miss packets in a "beacon"
(i.e. with Veronica) because of not locking onto the right frequency right
away.  Your mileage obviously varies!

I guess one thing to consider is that Veronica was high-pass filtered (to
make a clear space for the telemetry) manually before being loaded onto the
satellite, while repeater activity is obviously filtered in real time with
a different filter.  But that does not explain why it changed over time.

On Wed, Oct 3, 2018 at 6:40 PM, Albert van Deursen <avdeur at home.nl> wrote:

> Hi, I reacted two days ago on the SDR-radio.groups.io (forum users
> Console SDR software by Simon Brown) to a post from Hasan N0AN saying :
> I have been following Simon's advice trying to decode Fox1A with a good
> pass this evening. Plse note that until let's say 8 months ago I was
> perfectly able to decode these DUV signals using the standard Fox Telem
> decoder ver 1.06r. Than for reasons unknown to me all of a sudden I no
> longer could decode any packets on any of these 3 birds. Tried several
> options like reinstalling old version and again new version, trying
> different option within the program but with zero result. Also note that I
> always use Console as my Rx. Anyway gave up as also heard stories that the
> signal conditions of these sats were decreasing. ( against this is that I
> see EU stations still uploading valid packets to the AMSAT server...) Still
> in my backhead there was always something like "isn't this just an audio
> issue ??   Anyway will try later this evening a pass from AO-92 ( 23:09
> local time 44 degrees EL using SDR# and the HF+.. Also note that I used to
> use the WFM 15k option ( not NFM) as this was advised ( I vaguely remember)
> Not 100% sure though 73 .Will let you know the outcome of course. Also hope
> to learn the experience of other ham satellite decoders using V3. 73 Albert
> PD0OXW
> =============
> Well now this evening / tonight 22.00 UTC I bumped into a Fox1A pass at 40
> degrees which was dead silent so only once (a very clear) "Veronica" kicked
> in there was DUV signal...Flabbergasted I noted that the "eye" was perfect
> and during two identifiers I could decode 4 packets ( confirmed on Amsat
> Server)...
>
> I wonder why after months of inability to decode these signals all of a
> sudden the old status (correct decoding as since the start of the Telem
> software) seems to be back (without any change in de SDR Console software).
> Can it be the "the regular" HAM voice activity degrades the DUV download ?
>  Of course will try to check on all 3 85/91/92 tomorrow and revert. (plse
> note I use WIMO 2/70 X-CUADS antenna's  steered by  G-5500)
> 73
> Albert PD0OXW
>
> -----Original Message-----
> From: Burns Fisher [mailto:burns at fisher.cc]
> Sent: 02 October 2018 22:26
> To: Stephen E. Belter
> Cc: amsat-bb at amsat.org
> Subject: Re: [amsat-bb] FoxTelemetry on AO-91 and AO-92
>
> Hasan sent me a screen shot of his attempt to collect data from one of the
> Fox satellites.  I also showed it to Chris, G0KLA, the author of FoxTelem.
> We both agree that the problem is likely to be filtering.  SOMEWHERE in
> there is a high pass filter that is not allowing enough of the low
> frequencies through.  Another possibility is not FM demodulating a wide
> enough bandwidth.  You could try wide FM rather than narrow, or if it is
> adjustable, set it to 5KHz.
>
> Chris also says that he expects to be able to decode if the signal is only
> a few dB above the noise, so chances are good that a weak signal is not the
> problem.
>
> Good luck and 73,
>
> Burns WB1FJ
>
> On Tue, Oct 2, 2018 at 10:57 AM, Burns Fisher <burns at fisher.cc> wrote:
>
> > Let me add just a bit more.  I have a homebrew Lindenblad (circular
> > polarity, omni) with an AMSAT wide band preamp out at the antenna, going
> to
> > a FunCube Dongle that is decoded directly by FoxTelem.  I get hundreds of
> > packets per day with it.  I have also used an Arrow dual-band J-pole
> > mounted at 45 degrees and an AirSpy wide-band preamp with nearly as good
> > results.
> >
> > My experience is that I CAN get decodes without having completely full
> > quieting, but it still has to be "pretty good".  I also completely agree
> > with Steve that the big trick is to be sure you have no high pass
> > filtering.  Best is to use a software defined radio (I've succeeded with
> > both HDSDR and SDR# ) with virtual audio cable if you don't have a
> FunCube
> > Dongle.
> >
> > Good luck!  Let us know how you are doing.  Maybe a screen shot of
> > FoxTelem when there is a signal coming would be helpful (although I think
> > pictures don't go through on this mailing list).
> >
> > 73,
> >
> > Burns WB1FJ
> > Fox Flight Software
> >
> > On Tue, Oct 2, 2018 at 10:46 AM, Stephen E. Belter <seb at wintek.com>
> wrote:
> >
> >> Hasan,
> >>
> >> The answer to your question about the difficulty is yes, and no.
> >>
> >> There are lots of things that can block the decoding of the DUV.  Get
> any
> >> *one* of them wrong, and it doesn't work.  Get them *all* right, it
> works
> >> great.
> >>
> >> I am not an expert, but here are a few suggestions.
> >>
> >> You need a solid, full-quieting signal to decode the packets.  Mark is
> >> right; this is much more difficult with an omnidirectional antenna like
> an
> >> eggbeater.  With 80-feet of coax, you probably need a low-noise preamp
> at
> >> the antenna (not in the shack).  When you make a voice QSO, is the
> signal
> >> really full-quieting?
> >>
> >> The DUV information is very, very low frequency.  You need to be
> >> receiving everything from DC to 300 hertz, and passing it to FoxTelem.
> >> Typical FM receivers (conventional analog and software defined) filter
> out
> >> the low frequencies so as to not include CTCSS tones which add an
> annoying
> >> rumble or hum to the audio.  So carefully check and adjust or remove any
> >> low-frequency filtering.
> >>
> >> Using a patch cord to connect the speaker output to a sound card input
> is
> >> unlikely to work.  You need to be using a virtual audio cable (software
> >> utility that simulates two sound cards connected by a patch cord).
> Paul is
> >> correct, check the sample rates on the SDRC output, the input and
> output of
> >> your VAC, and the input to FoxTelem.  They should all be identical.
> >>
> >> Check the levels to make sure nothing is clipping or overloaded:
> Windows
> >> levels between the HF+ and SDRC, SDRC output, and VAC input and output.
> >> I'm using a FUNcube Pro+ dongle and have the Windows level on the FCD
> set
> >> to 9 instead of the default 100.  The best level for your HF+ may be
> >> different.
> >>
> >> I'm sorry you're having trouble.  Maybe these hints and the suggestions
> >> of others will help.
> >>
> >> 73, Steve N9IP
> >> --
> >> Steve Belter, seb at wintek.com
> >>
> >>
> >>
> >> On 10/2/18, 7:56 AM, "AMSAT-BB on behalf of Hasan al-Basri" <
> >> amsat-bb-bounces at amsat.org on behalf of hbasri.schiers6 at gmail.com>
> wrote:
> >>
> >>     Several of us are having a heck of a time getting any telemetry from
> >> the
> >>     above birds. DUV just isn't producing anything.
> >>
> >>     We hear both well enough to make QSOs on the FM transponders, but we
> >> can't
> >>     seem to get any data thru the decoder.
> >>
> >>     Is it really that much more difficult to get the TLM via DUV  than
> to
> >>     listen to a voice on the 2m downlink?
> >>
> >>     Setup:
> >>     2m Eggbeater at 7', fed with 80' of 9913
> >>     AirSpy HF+ SDR
> >>     SDRC V3 Software
> >>     FMN 12 kHz (Highpass Filter not checked) and FMW both tried, neither
> >>     produce any decoded data.
> >>
> >>     I am getting telemetry just fine from AO-73, and am also getting
> >> perfect Wx
> >>     pix on 137.100 with SNR's of > 30 dB.
> >>
> >>     Am I doing something wrong, or is it just that hard to get FoxTelem
> >> to work
> >>     with DUV?
> >>
> >>     Thanks for any help. 73,
> >>     N0AN
> >>     Hasan
> >>     _______________________________________________
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> >>
> >> _______________________________________________
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