[amsat-bb] Re Update on FunCube-3 / EO-79 Interference

Scott scott23192 at gmail.com
Sun Nov 13 18:11:39 UTC 2016

Many thanks to you both, David & Dani, for the great explanations.  I 
certainly learn something every day.

I was just concerned that there was a noise (or data) source somewhere since 
the operators on SSB were reporting interference and that the sat was 
"difficult to work", etc.

And since I had not seen anything similar on, say, FO-29, it was a different 
looking waveform on the waterfall to me.  But of course every satellite is 




-----Original Message----- 
From: David G0MRF via AMSAT-BB
Sent: Sunday, November 13, 2016 12:47 PM
To: amsat-bb at amsat.org
Subject: [amsat-bb] Re Update on FunCube-3 / EO-79 Interference

Hi Scott.

Thanks for the dropbox image.- A picture is worth a thousand words as they 

What you can see in the image is the output of the transponder across its 
25kHz passband.

If the signal was a little stronger you would see the level in the waterfall 
rise across the entire 25kHz
As it is, you can see two distinct peaks, and some narrow band signals from 
people transmitting up to the satellite.

The lower part of the picture shows how the signal received from the 
satellite is changing with time.
This is probably the signal increasing and decreasing at your receiver as 
the satellite slowly spins in its orbit
.- This is quite normal if you have a 'linear' antenna, say horizontal, 
while the satellites antenna is moving from horizontal (giving a strong 
signal to you)
to vertical - which will produce a much weaker output from your receiver.

Hope that helps.

David G0MRF


Yesterday I reported on my observation of a possible 25k-wide data stream
interfering with amateur CW & SSB on FunCube-3 / EO-79 (QB50P1).  I was not
able to decode the data nor did I see any obvious match for a source
(terrestrial nor another satellite).

On today's 16:14 UTC pass over the USA East Coast, I saw the same wideband
stream resembling telemetry data but would like to add to yesterday's

I have uploaded a screen shot of my waterfall showing how the wideband
stream comes & goes in response to activation of the transponder at:


-Scott,  K4KDR
Montpelier, VA  USA 

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