[Elecraft] [K3] dB Changes, Loudness, and Signal to Noise Ratio

[Bill W4ZV]

Guy, K2AV wrote:
> 
> I'm sorry, but didn't you just prove that it took over 3 dB to make
> the signal generally copyable from possibly copyable?  Potentially
> copiable at 27 uW (because one did), generally copyable at 80 uW, a
> difference of 4.7 dB.
> 

No Guy, I proved -1.3 dB (20 uW versus 27 uW) was the difference in one
station and operator (i.e. yours truly) just detecting the signal versus
having verified copy.

End of thread per Eric's request.

73,  Bill

On Tue, Dec 15, 2009 at 4:33 PM, Bill W4ZV <btippett at alum.mit.edu> wrote:

> There was an interesting series of low power beacon receiving tests
> conducted in December 2004 through January 2005 by N2XE.  John sent a
> beacon
> ID message including a unique code word at various power levels on 80m
> over
> a several day period.  You had to correctly copy each code word correctly
> to
> verify reception.  There's a lot of documentation on the Topband and QRP-L
> lists over that period, but here's a brief summary of the results:
>
> 80 uW - 8 stations correctly copied.
> 40 uW - 1 station
> 27 uW - 1 station
> 20 uW - 0 stations.
>
> The power difference in dB at each succeeding lower level was (top to
> bottom):
>
> -3 dB (i.e. the 80 uW to 40 uW test)
> -1.7 dB
> -1.3 dB
>
> I copied the beacon at both the 40 uW and 27 uW levels but could not
> decipher the code word at 20 uW even though I could detect presence of the
> signal.  
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