--- In [email protected], "Jim B." <[EMAIL PROTECTED]> wrote:
"... Another thing to think about-the 3 dB power change ISN'T what
you're hearing. To really compare apples to apples, you have to
measure the sound output (SPL) change that the 3 dB change creates>
Jim Barbour
WD8CHL
(yikes)"
___________________________________________________________________
Huh???? You must be stuck thinking SSB / AM
Those 3dB are carrier power. What you are listening to is the
quality of the demodulated signal at the target receiving unit.
It is generally accepted industry practice for path reliability
projection, e.g. Motorola Coverage Acceptance Standards, that 4dB
C/N is the point at which an FM communications receiver delivers 12
dB SINAD and that 7 dB C/N is the point at which such a receiver
delivers 20 dB quieting.
Hence, it follows that a 3dB change in transmitter power [or
increase in antenna gain OR reduction of path loss] which will
result in a corresponding 3 dB improvement of received C/N would be
sufficient to:
A] take a received signal from 1 dB C/N [unreadable] to 12 dB SINAD.
-OR-
B] Take a received signal from 12 dB SINAD to 20 dB quieting - a
very noticible audible improvement in DAQ [Delivered Audio Quality] -
a metric that has been used extensively in radio coverage
prediction and verification.
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