From: Bob Blick <bobblick@outlook.com>
To: Microcontroller discussion list - Public. <piclist@mit.edu>
Sender: "piclist-bounces@mit.edu" <piclist-bounces@mit.edu>
Date: Mon, 10 Aug 2020 14:27:33 -0700
Subject: Re: [EE] averaging multiple samples to reject AC interference
Thread-Topic: [EE] averaging multiple samples to reject AC interference
Thread-Index: AQHWb0qAtaM9BhVbvUOM7lgsOkiRlqkxyeN7gAARaEE=
Message-ID:
 <BYAPR02MB4055A2959D640B1B09140440DC440@BYAPR02MB4055.namprd02.prod.outlook.com>
References:
 <BYAPR02MB40553CD9F4B18FEF130B4F36DC440@BYAPR02MB4055.namprd02.prod.outlook.com>,
	<87ebbde6f2952158e80cf62518bc8745@mtlp000083>
In-Reply-To: <87ebbde6f2952158e80cf62518bc8745@mtlp000083>
Reply-To: Microcontroller discussion list - Public. <piclist@mit.edu>
Accept-Language: en-US
Content-Language: en-US
X-MS-Exchange-Organization-SenderIdResult: Pass
X-MS-Exchange-Organization-PRD: mit.edu
X-MS-TNEF-Correlator:
acceptlanguage: en-US
received-spf: Pass (protection.outlook.com: domain of outlook.com designates
	40.92.23.44 as permitted sender) receiver=protection.outlook.com;
	client-ip=40.92.23.44;	helo=NAM12-MW2-obe.outbound.protection.outlook.com; 
dkim-signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=outlook.com;
	s=selector1;
	h=From:Date:Subject:Message-ID:Content-Type:MIME-Version:X-MS-Exchange-SenderADCheck;
	bh=a6I2qx5EFxR769Un6c1mRnlo8yd2wshZVtGmVkiQ1fo=;
	b=eMr7BjHnz98I79/NjWoX/rJF+nRVeJwFO3JCQlZRS8fi0rQpBUy4uj/Syenn7bqk/BBH/7q/hoCh0JA0mnWfzNjeOZ9y+Fnn1m+q4Vnc/9wlIdhqZzj8cqHsvIYrTptOBhnWCkaVt9QySFG0FIRIj7VdVZvy5nyLbBw8bvNGCYcb6P3ezY2Aupxnq89/KQeaB8/9rWvE8V5XfMPE12NoA2eXIv+CuXPKBcJjo1J3u1t683hiRI08fgx8q8slEKImuyrw82U+APfBhQZrzslpxdqQ1SXsufha6U0QuT9D5iUox0+5Nf9CwQ5yfX/83nwPXihcqhvOKXOAQg26ihl3Fg==
authentication-results: spf=pass (sender IP is 40.92.23.44)
	smtp.mailfrom=outlook.com; mit.edu; dkim=pass (signature was verified)
	header.d=outlook.com; mit.edu;	dmarc=pass action=none
 header.from=outlook.com; 
errors-to: piclist-bounces@mit.edu
list-id: "Microcontroller discussion list - Public." <piclist.mit.edu>
list-post: <mailto:piclist@mit.edu>
x-beenthere: piclist@mit.edu
x-mailman-version: 2.1.6
x-topics: [EE]
x-mime-autoconverted: from quoted-printable to 8bit by PCH.mit.edu id
	07ALS1ee007742
Content-Type: text/plain; charset="us-ascii"
Content-Transfer-Encoding: quoted-printable
MIME-Version: 1.0

Hi Dwayne,
That's exactly what I wanted to hear. Thanks!
Bob

________________________________________
From: piclist-bounces@mit.edu <piclist-bounces@mit.edu> on behalf of Dwayne=
 Reid
Sent: Monday, August 10, 2020 1:14 PM
To: Microcontroller discussion list - Public.
Subject: Re: [EE] averaging multiple samples to reject AC interference

Hi there, Bob.

Old-time Dual-Slope digital meter systems did exactly what you
describe, with great effectiveness.

dwayne


At 01:44 PM 8/10/2020, Bob Blick wrote:
>I have sensors that feed an instrumentation amplifier running a
>voltage gain of 10 before going into the A/D converter of a microcontrolle=
r.
>
>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 is not conducted interference or power supply
>ripple. Shielding is not possible. I only need to process the signal
>about 4 or 5 times per second. The signal is changing, so long-term
>averaging is bad. Actually any averaging will 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 second period, that should give some improvement at 50Hz and
>60Hz without getting too involved, correct? This would fit into my
>existing multiplexing constraints.
>
>I seem to recall being in this situation before but forget what I
>did at the time.
>
>Thanks for any suggestions.
>Bob

--=20
http://www.piclist.com/techref/piclist PIC/SX FAQ & list archive
View/change your membership options at
http://mailman.mit.edu/mailman/listinfo/piclist
.