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Re: [CQ-Contest] Congrats to Russian DX Contest cracking downcheating

To: <cq-contest@contesting.com>
Subject: Re: [CQ-Contest] Congrats to Russian DX Contest cracking downcheating
From: "Ward Silver" <hwardsil@gmail.com>
Reply-to: Ward Silver <hwardsil@gmail.com>
Date: Sat, 12 Feb 2011 18:37:46 -0600
List-post: <cq-contest@contesting.com">mailto:cq-contest@contesting.com>
> For those of you who have never seen a skimmer operating, it
> does NOT give an absolute signal strength, it give an SNR value.

To translate SNR into absolute signal level it would be relatively 
straightforward and inexpensive to inject a signal into the receiver's front 
end from a calibrated signal source - say, -20 dBm - at or just outside a 
band edge.  The signal would not be radiated and so not subject to any rules 
pertaining to transmitted signals.  A crystal oscillator and an attenuator 
would suffice.  If the signal source was keyed to be recognized by the 
Skimmer ("CQ CQ CQ de CAL CAL CAL") it would become part of the spot 
database without any post-processing being required. There are other 
receiver linearity issues to deal with but this would be an easy first step 
that would enable widespread post-processing and open up the discussion.

73, Ward N0AX 

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