Re: Log amps? for dB metering.

Thanks Mark,
This is for audio up to 200Khz


"Mark" <makolber@xxxxxxxxx> wrote in message
news:1162267195.944343.128840@xxxxxxxxxxxxxxxxxxxxxxxxxxxxxx

r.laury@xxxxxxxxxxx wrote:
I'm trying to come up with an LCD dBv meter. Not the bargraph type but a
numeric LCD type. It needs to have a range of +30 down to -70. 100 dB
total range.
the reference is .775V = "0" dBv. I want to use one of the PIC's for the
controller.
My question is should I use a Log amp to do the log calculations or think
about doing it
in software. The smaller pic's I've looked at don't offer much math
capability.
To do the calculations in hardware I think I'll need an RMS to DC
converter,
and a LOG amp. Then I would read the output of the LOG amp into the A/D
converter in the PIC.
Any Ideas?

Thanks

Is this for audio or RF signals?

For RF I would look a successive detection chips that convert AC to log
DC. They might be usable for audio too.

Mark



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