From: Dwayne Reid <dwayner@planet.eon.net>
To: pic microcontroller discussion list <piclist@mit.edu>
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Date: Tue, 6 Oct 2020 12:18:14 -0700
Subject: [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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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=20
is about to be on us.  One of the roof-top HVAC boxes on our building=20
appears to have a gas ignition problem.  I hear explosions both quiet=20
and loud when the heater turns on.

This is obviously a gas ignition problem and we have called the=20
service people a couple of times to get this fixed before the heat=20
exchanger becomes damaged.  Specifically, what I think is that the=20
fuel gas (Natural Gas) is accumulating in some area away from the=20
ignitor, reaching some level higher than the Lower Explosive Level,=20
then some traces of the fuel reaching the ignitor.

But the service people can't see any problem and they are questioning=20
whether I am just imagining the problem.

What I would like to do is to set up one of my spare Android devices=20
with the microphone in the heating duct.  But I need some way to have=20
the device record just of few seconds BEFORE the explosion occurs as=20
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=20
hoping that someone here might have a suggestion.

Note that I'm not married to the idea of using an Android device -=20
just that's what I have handy.  I could also set up a laptop or=20
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=20
various types, microphones ranging from really inexpensive to stupid=20
expensive, audio recorders of various types.

Problem is that none of the audio recorders that I have (DAT, SD-card=20
based, Compact Flash based, etc) have the capability to continuously=20
record a buffer, then capture several seconds before and after the=20
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
Dwayne Reid   <dwayner@planet.eon.net>
Trinity Electronics Systems Ltd    Edmonton, AB, CANADA
780-489-3199 voice   780-487-6397 fax   888-489-3199 Toll Free
www.trinity-electronics.com
Custom Electronics Design and Manufacturing

--=20
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