Re: circuit design to measure signal level variation ?


"Karl Uppiano" <karl.uppiano@xxxxxxxxxxx> wrote in message
news:EqtSf.14707$%e1.6434@xxxxxxxxxxx

S-meters are often tied to the AGC, since the AGC amp and related
detection circuitry is already there, and because once you have gotten the
AGC into the active region, output signal level is relatively constant (by
definition), and not useful as a signal strength indicator. It will be
somewhat difficult to measure signal level below the AGC threshold, since
the AGC will not respond to changes in signal level below the threshold.

I'm pretty sure that I am going to need to measure the signal below the
point at which the AGC kicks in.

Will you have a computer anywhere in your application? If so, you could
use a linear A/D converter to feed the computer, and then program any
function (logarithmic or otherwise*) into a lookup table in the computer.

I will be looking at the output from this signal level detection circuit
with the ADC of a microcontroller.

*I suspect your logarithmic function is only a first approximation anyway,

I wasn't thinking that way . . . why is it that you suspect that?

Thanks,
Scott


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