Receiving Telemetry

For the early roll-out of the Dashboard

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Receiving Telemetry

Postby W0RK » Mon Jan 19, 2015 5:34 pm

My reception of Funcube telemetry is very hit or miss. My station setup is a homebrew turnstile antenna (with radials) at about 25' with no obstructions, about 40' of high quality RG-8 coax, an Icom IC-746, and a PC running Windows 7, SatPC32 for doppler, and the dashboard software. After watching several passes, it looks like I can receive a good part of a south to north pass, but hardly any of a north to south pass (there was just such a pass at 60+ degrees and I didn't decode a single packet). I'm new at this, is this something to do with the orientation of my antenna? Is a turnstile not enough antenna for this application?

Secondly, I use the AF out on the accessory jack of my IC-746 to feed the sound card in my laptop. When a pass goes by I can open the normal audio gain (it doesn't affect the AF out jack) and hear the satellite, almost as soon as SatPC32 says I should. Even though my ear can hear data, the dashboard doesn't seem to decode it. Even when it gets very loud to my ear.If I click the monitor audio box, I can hear the satellite on my laptop speakers as well, still I don't see any packets decoded.

I know it's a lot more complicated than just hearing the packets. Are there some settings I can adjust in the dashboard software and/or my laptop sound card to help improve reception and decoding? Do I need a pretty good sound card to get the best out of the dashboard software?

Thanks in advance for any insight...

Kelley
W0RK
 
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Joined: Sat Jan 17, 2015 3:12 am

Re: Receiving Telemetry

Postby g4dpz » Mon Jan 19, 2015 5:39 pm

Hi
At what time were you trying to receive packets?

Between 09:30 utc Friday and 22:00 utc Sunday the beacon is in
low power 30mW mode. It is also in that mode during elipse.

73

Dave G4DPZ
FUNcube Team Member
g4dpz
 
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Re: Receiving Telemetry

Postby W0RK » Mon Jan 19, 2015 5:51 pm

Hi Dave,

I've been trying to receive almost everyday during the last two weeks or so. The pass where I didn't decode any packets was just this morning, a little less than an hour ago (I'm in the north central US). Yesterday on the 23:00 pass I received many packets (I believe a south to north pass).

Kelley
W0RK
 
Posts: 6
Joined: Sat Jan 17, 2015 3:12 am

Re: Receiving Telemetry

Postby g4dpz » Mon Jan 19, 2015 6:02 pm

Hi

If you are using satpc32 to correct for doppler you may be suffering
because the transmit frequency is subject to frequency shift
due to temperature.

Did you successfully upload data to the warehouse. If so, I can correllate the
temps when you got good copy and when not.

Dave
g4dpz
 
Posts: 143
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Re: Receiving Telemetry

Postby W0RK » Mon Jan 19, 2015 6:09 pm

I am setup to upload to the data warehouse. I see my callsign on the upload ranking list with a count of 420 at this point.
W0RK
 
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Re: Receiving Telemetry

Postby g4dpz » Mon Jan 19, 2015 6:10 pm

Hi

I'll take a look when I get home.

73

Dave
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Posts: 143
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Re: Receiving Telemetry

Postby W0RK » Mon Jan 19, 2015 6:33 pm

Thanks Dave.
W0RK
 
Posts: 6
Joined: Sat Jan 17, 2015 3:12 am

Re: Receiving Telemetry

Postby g4dpz » Mon Jan 19, 2015 11:05 pm

Hi

Just checked the database and I can see the 420 frames.

They were collected when the internal temp was between
-1 and +9. The internal temp can go as high as +18, so I think
it might be affecting the doppler calcs.

I don't know satpc32 but can you add a small offset during a
pass.

Dave
g4dpz
 
Posts: 143
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Re: Receiving Telemetry

Postby W0RK » Mon Jan 19, 2015 11:53 pm

Hi Dave,

I just started using SatPC32 myself, but I think I can add an offset. How big should it be?

Thanks for all your help!

Kelley
W0RK
 
Posts: 6
Joined: Sat Jan 17, 2015 3:12 am


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