[amsat-bb] AO-85

Patrick STODDARD (WD9EWK/VA7EWK) amsat-bb at wd9ewk.net
Wed Jul 13 16:00:11 UTC 2016


I don't think there is just one common reason why the FoxTelem
program won't decode. I have seen a few instances where different
solutions fixed the problem. I don't normally use an RTL-SDR
dongle for copying telemetry from AO-85 (or AO-73), but I have a
few questions...

1. What is the output bandwidth in HDSDR - 48000, 96000, ...? It
should match the bandwidth you have in FoxTelem, although there is
one circumstance I have come across where that is definitely not
the case. I know you mentioned using 48000 all around, but there have
been times I have seen the output bandwidth changed in HDSDR when
I go to use it. I now check it every time I start the program,
whether for

2. Are you using a virtual audio cable to connect HDSDR to FoxTelem?
If so, which one? Or, for older Windows PCs, are you using the
"Stereo Mix" device that came with many PCs running Windows XP
or Windows 7?

3. In FoxTelem, did you select the RTL-SDR dongle in the dropdown
listing on the main screen? AF or IQ? Bandwidth there set to 48000?

4. You mentioned you manually track the Doppler. Have you tried the
AFC function in HDSDR, to let that program do the tracking for you?

5. Using the latest version of FoxTelem? Have you tried uninstalling
FoxTelem, then reinstalling it (or installing the latest version)?

I use HDSDR, Virtual Audio Cable, and the FoxTelem program with either
the FUNcube Dongle Pro+ or an SDRplay receiver. With this combination,
I have to set my Output Bandwidth from HDSDR to 96000, the bandwidth
in the virtual audio cable to 96000, but set FoxTelem's bandwidth
to 48000 in order to properly decode telemetry. This was not an
issue if I used a FUNcube Dongle Pro+ directly with FoxTelem,
cutting out HDSDR and a virtual audio cable, nor was it an issue if
I had HDSDR and FoxTelem both using the FUNcube Dongle Pro+
directly and bypassing a virtual audio cable. The FUNcube Dongle
Pro+ presents itself to Windows as an audio device, and as long as
I use the same center/LO frequency in both programs I don't need
to use a virtual audio cable to tie HDSDR to FoxTelem (or the
FUNcube Dashboard, when receiving telemetry from either AO-73 or


Twitter: @WD9EWK

On Tue, Jul 12, 2016 at 11:51 PM, <skristof at etczone.com> wrote:

> So, what's the most common reason that the FoxTelem program won't
> decode?
> I'm running HDSDR software with an RTL-SDR dongle. It has worked in the
> past, but hasn't been decoding for about two weeks now. I can see the
> peak of the AO-85 on the HDSDR screen and manually track the doppler
> shift. Everybody is set to 48000 sample rate. I get perfect "eyes" on
> the FoxTelem screen. But zero decoding.
> Anybody got any hints or tips?
> Steve AI9IN
> ______________________________

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