From: Bob Blick <bobblick@outlook.com>
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Date: Mon, 10 Aug 2020 12:44:07 -0700
Subject: [EE] averaging multiple samples to reject AC interference
Thread-Topic: [EE] averaging multiple samples to reject AC interference
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I have sensors that feed an instrumentation amplifier running a voltage gai=
n of 10 before going into the A/D converter of a microcontroller.

There is AC line interference. It is small, but if I can reduce the effect,=
 that would be good. I'm in the 60 Hertz part of the world, but ultimately =
this will be used in both 50Hz and 60Hz locations. Battery operated, this i=
s not conducted interference or power supply ripple. Shielding is not possi=
ble. I only need to process the signal about 4 or 5 times per second. The s=
ignal is changing, so long-term averaging is bad. Actually any averaging wi=
ll result in a tradeoff between response time and accuracy that I will need=
 to evaluate.

These sensors are multiplexed with others and I can't sample continuously.

If I average multiple samples taken at 1/300 second intervals over a 1/10 s=
econd period, that should give some improvement at 50Hz and 60Hz without ge=
tting too involved, correct? This would fit into my existing multiplexing c=
onstraints.

I seem to recall being in this situation before but forget what I did at th=
e time.

Thanks for any suggestions.
Bob
--=20
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