[Skimmertalk] What causes audio images with QS1Rs?

[Pete Smith N4ZR]

During the ARRL CW contest, we had two Skimmers using the QS1R/Skimmer 
Server combination that each produced many false spots, with the 
"signature" commonly associated with Skimmers using simple SDRs, ones 
which rely on a computer sound card for A/D conversion. That is, the two 
spots are spaced equidistant from the receiver's center frequency, one 
is significantly stronger than the other, and they arrive at the server 
typically within the same second.

We're having no luck isolating what is different about those particular 
systems.  So far we've ruled out inadequate power supplies, and the idea 
of excessive gain before the receiver doesn't look promising.  Does 
anyone have any theories we can explore?  I'll be glad to provide the 
data in Excel format for anyone who wants it.

Thanks in advance!

-- 

73, Pete N4ZR
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