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

David G0MRF g0mrf at aol.com
Sun Nov 13 17:47:17 UTC 2016


Hi Scott.

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

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
comment......................



I have uploaded a screen shot of my waterfall showing how the wideband
stream comes & goes in response to activation of the transponder at:
https://dl.dropboxusercontent.com/u/31460496/ham/2016-11-13--EO-79.png

73,

-Scott,  K4KDR
Montpelier, VA  USA



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