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

[Burns Fisher]

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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