How to get more telemetry frames ?

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How to get more telemetry frames ?

Postby PA1LH » Sat May 09, 2015 9:27 am

Hello all,

Since a few weeks i use the dashboard to get telemetry from the FUNCUBE-1.
The problem is that it is very hard to get the right signal to receive the telemetry.
I try to tune my receiver (Yaesu FT-817) by hand, by following the dopplershift.
But most of the time i don't receive anything .... wich can be very frustrating.
In the last 3 weeks, i have only got 4 frames wich were sent to the warehouse.

Is there something that i do wrong? I will explaine what i do, en what my setup here is:
To begin with the setup:
I use a Yaesu-FT-817, wich is connected to the soundcard of my computer with a stereo audiocable.
My antenna is a homebrew 2m/70cm socalled flowerpot antenne, wich is working quite well: i can receive the WX-sats with it as well. The antenne is about 6 metres from the ground, not very high though, but it works.

What i do to receive the FUNCUBE-1:
I use Orbitron to follow it. Once it is close enough, i start listening on 145.937, and as soon as i hear it, i start tuning with the dopplershift.
Problem is, i can tune what i want, but most of the time i do not reveive anything, or (like i allready explained) only e few frames.
*As i was writing this massage, i received the FUNCUBE within just 15 seconds !! A new record for me HI!! The dashboard sent 3 new frames to the warehouse.
What i want to know is: how can i increase the amount of frames ?? Is increasing the antenna hight good enough, or can i do something else to get more frames ?

I Always thought that it was right to go for the high pitch tone from the FUNCUBE, but today i found out that that is NOT the case.
Today i got the telemetry when i heard a low pitch in the FUNCUBE signal.
So, if there is anybody who can give me some ideas to get more frames, please let me know.

PA1LH.
PA1LH
 
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Re: How to get more telemetry frames ?

Postby wd9ewk » Mon May 11, 2015 5:35 pm

Hi!

When are you trying to receive the telemetry? If you are trying when the transponder is active (usually on weekends), the telemetry downlink is only at 30mW at those times. On weekdays when the transponder is normally off, the telemetry downlink is at 300mW. This makes a huge difference in terms of how many frames you successfully copy on each pass.

On weekends or when the transponder is on, I am lucky to get more than 3 or 4 frames per pass - even when the satellite is very high in the sky. I can copy 60 to 80 frames per pass with the 300mW telemetry using a log periodic antenna, and over 100 frames per pass when using the AMSAT-UK 2m crossed dipole. I use a FUNcube Dongle Pro+ as my receiver for the telemetry, and sometimes when working the transponder.

Good luck, and 73!
Patrick WD9EWK/VA7EWK
http://www.wd9ewk.net/ - Twitter: @WD9EWK
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Re: How to get more telemetry frames ?

Postby AL0I » Tue May 12, 2015 9:52 am

This thread may be helpful:

viewtopic.php?f=9&t=226

You can test your computer scheme and audio cable by using the sample audio files provided by the FUNcube project here:

http://funcube.org.uk/working-documents ... -examples/

You can feed Example 6 or Example 7 to your computer running the FUNcube client using an MP3 player or another computer or even feed the headphone/speaker output of your computer back into the microphone/line input as you play the sample.

This MP3 file (Example 6 available on the page above) should match what you hear with your non-SDR receiver fairly closely (without the Doppler shift):

http://pa3weg.nl/funcube/recordings/FUN ... signal.mp3
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Re: How to get more telemetry frames ?

Postby PA1LH » Wed May 13, 2015 9:50 pm

@Patrick and ALoI, thank you for your replies.
I think that i located the problem of not getting to many readings from the funcube: I tuned to high in search for the telemetry. But now i know were to look for it. When the cube is on 300mW, i can get 40 of more frames. This evening i got 72 frames !!
My score in de warehouse goes up now :)
I use two antennes now: a vertical flowerpot antenne for 2m/70cm, and since today also a homebrew QFH antenne.
Both antennas are working very well for a simple homebrew antenne.

Thanks again for your help.

73,
PA1LH, Leon.
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