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

Scott scott23192 at gmail.com
Sun Nov 13 16:55:46 UTC 2016


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.

>From watching numerous hams attempt to find their downlink signal or in
some cases make successful SSB or CW contacts, it became obvious that the
"data" stream that I was seeing was only present when someone was actively
transmitting through the transponder.  No carrier on the uplink/downlink -
no wideband signal.  But when there was an SSB or CW signal present, the
wideband stream would begin also.

Please note that the match is not EXACT... sometimes there was a slight
delay in the appearance of the wideband stream when the transponder was
activated.  But when you watch it "live", the relationship was obvious.

I am not even remotely familiar enough with how a liner transponder works
offer any technical explanation for this behavior, but just wanted to add
my observations to the conversation.

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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