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[AMPS] True Or Not True #2

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Subject: [AMPS] True Or Not True #2
From: (Jim Barber)
Date: Fri, 07 Sep 2001 02:47:37 -0700

>Knowing that's not easy to deal with an AGC voltage in the way to 
>produce a constant S-meter movement, in the digital era it's easy to 
>correct the readings associating the correct offset to different AGC 
>voltages and also taking in account for attenuators or preamplifiers.
>It seems design engineers still do not consider this opportunity that's 
>instead widely used in other equipments.
>Mauri I4JMY

Another related problem is keeping the receiver gain flat
from 1.8 to 30mhz.  You could keep a separate correction
table for each band, but that takes a lot of memory space.
It would also have to be reset any time the receiver was
serviced, and subject to calibration error over time.

The above isn't impossible, (especially if the processor runs
from a EEPROM) but with all the other variables in the system,
I don't see any major advantage to an "absolute" s-meter
calibration.  On the other hand, correcting the meter response
so that it reflects relative level changes more accurately would
be worthwhile, I think.  For example, regardless of the
absolute level for S-5, having it reflect that S-6 truly
is 6db higher would be useful.

My .02, 
Jim, N7CXI

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