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[AMPS] True Or Not True #2

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Subject: [AMPS] True Or Not True #2
From: (Tom Rauch)
Date: Thu, 6 Sep 2001 21:50:38 -0400
> However, if the signal was at or near the noise level, then 2 db
> increase could make the signal more easily read.  A 2db increase is
> like Christmas to someone using a single yagi for moonbounce.

Even 1dB is a huge increase when copying a signal near noise. 
The error rate changes considerably here when working CW, when 
I pick antennas that offer even 1dB more S/N ratio.

Most S meters are in the area of a dB or two at the low end of the 
S scale, expanding as they get up around S-9 and they work fairly 
well from that point on. My ICOM's are that was, as is my Yaesu 
stuff. Almost no receivers are 6dB, most are 3 to 5 at the middle 
scale. Most receivers actually tried for 5 dB per S unit, not 6. But 
of course the calibration is often all over the place in different scale 
areas, being much fewer dB per S unit at the low end. 

Because we often see a 1 S unit change when it is only 2dB or so, 
we often don't realize how much a dB or two actually means on 
weak signals.

That's also why so many antennas have "supergain" or super F/B 
on the air. Because people just assume an S unit is 6dB.

73, Tom W8JI 

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