From: Bob Blick <bobblick@outlook.com>
To: Microcontroller discussion list - Public. <piclist@mit.edu>
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Date: Tue, 6 Oct 2020 16:42:05 -0700
Subject: Re: [EE] Looking for technique to record audio after level exceeds
	some value
Thread-Topic: [EE] Looking for technique to record audio after level exceeds
	some value
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Hi Dwayne,

I don't know about an Android app, but if I was trying to do the task, I'd =
use a Wyze Cam, which I already have several of. It records a 12 second cli=
p each time an event happens, sound and video. You can use audio level as a=
n event. The recordings appear to be centered somewhere on the event, so yo=
u should get the full thing. If you put an SD card in the camera it also wi=
ll record 24 hours a day, and the little clips you get have a time stamp so=
 you can find the needle in the SD card haystack, should you desire. Even w=
ithout an SD card it is quite useful, although it only stores 14 days of cl=
ips, maximum 1 per minute. "in the cloud".

$19.99 US plus shipping, comes with magnetic mount.

Friendly regards, Bob

________________________________________
From: piclist-bounces@mit.edu <piclist-bounces@mit.edu> on behalf of Dwayne=
 Reid=20
Sent: Tuesday, October 6, 2020 12:18 PM
To: pic microcontroller discussion list
Subject: [EE] Looking for technique to record audio after level exceeds som=
e value

Good day to all.

I have a peculiar problem and I am hoping there is an off-the-shelf solutio=
n.

It is approaching winter in Canada, which means that heating season
is about to be on us.  One of the roof-top HVAC boxes on our building
appears to have a gas ignition problem.  I hear explosions both quiet
and loud when the heater turns on.

This is obviously a gas ignition problem and we have called the
service people a couple of times to get this fixed before the heat
exchanger becomes damaged.  Specifically, what I think is that the
fuel gas (Natural Gas) is accumulating in some area away from the
ignitor, reaching some level higher than the Lower Explosive Level,
then some traces of the fuel reaching the ignitor.

But the service people can't see any problem and they are questioning
whether I am just imagining the problem.

What I would like to do is to set up one of my spare Android devices
with the microphone in the heating duct.  But I need some way to have
the device record just of few seconds BEFORE the explosion occurs as
well as a few seconds AFTER the explosion occurs.

Kind of like how pre-trigger works with a DSO.

I've been looking but have not yet found an app that does this.  I'm
hoping that someone here might have a suggestion.

Note that I'm not married to the idea of using an Android device -
just that's what I have handy.  I could also set up a laptop or
netbook running Windows or DOS if I can find an appropriate application.

I do have a fair amount of audio equipment here - mixers, preamps of
various types, microphones ranging from really inexpensive to stupid
expensive, audio recorders of various types.

Problem is that none of the audio recorders that I have (DAT, SD-card
based, Compact Flash based, etc) have the capability to continuously
record a buffer, then capture several seconds before and after the
loud sound occurs.

Individual files with time stamps would also be desirable.

IBM compatible Shareware or paid Android app is just fine.

Suggestions gratefully accepted.

dwayne


--=20
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