[EE] Looking for technique to record audio after level exceeds some value

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[EE] Looking for technique to record audio after level exceeds some value

Dwayne Reid
Good day to all.

I have a peculiar problem and I am hoping there is an off-the-shelf solution.

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

--
Dwayne Reid   <[hidden email]>
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

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Re: [EE] Looking for technique to record audio after level exceeds some value

Richard Prosser
There's an app called "SnoreLab" that does that sort of thing for snoring -
not sure if it would work in your application as it seems to filter non
snore noises. Or try one of the webcam apps (ipwebcam ?) , some of them
will trigger on noise or movement & play back a few seconds before & after
the event. With an old cellphone, you may be able to capture the flash.

RP


On Wed, 7 Oct 2020 at 08:18, Dwayne Reid <[hidden email]> wrote:

> Good day to all.
>
> I have a peculiar problem and I am hoping there is an off-the-shelf
> solution.
>
> 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
>
> --
> Dwayne Reid   <[hidden email]>
> 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
>
> --
> http://www.piclist.com/techref/piclist PIC/SX FAQ & list archive
> View/change your membership options at
> http://mailman.mit.edu/mailman/listinfo/piclist
>
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Re: [EE] Looking for technique to record audio after level exceeds some value

Adam Field
In reply to this post by Dwayne Reid
On Tue, Oct 6, 2020 at 3:19 PM Dwayne Reid <[hidden email]> wrote:

>
> 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.
>
>
> I would record for as long as it takes to capture the event, then load the
audio in an editor like Audacity, one with a time spectrogram and go look
for the event visually.

https://www.audacityteam.org/about/screenshots/

However, this is dependent on not capturing ambient noises.
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Re: [EE] Looking for technique to record audio after level exceeds some value

Paul & Lynn Tyrer-2
In reply to this post by Dwayne Reid
I would use a Sd card based security camera, Records prior to sound and during.


> On Oct 6, 2020, at 3:18 PM, Dwayne Reid <[hidden email]> wrote:
>
> Good day to all.
>
> I have a peculiar problem and I am hoping there is an off-the-shelf solution.
>
> 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
>
> --
> Dwayne Reid   <[hidden email]>
> 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
>
> --
> http://www.piclist.com/techref/piclist PIC/SX FAQ & list archive
> View/change your membership options at
> http://mailman.mit.edu/mailman/listinfo/piclist


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Re: [EE] Looking for technique to record audio after level exceedssome value

Allen Mulvey
In reply to this post by Richard Prosser
Check your available audio equipment. If any of it is digital it may have a pre-record mode. I have two digital mixers both can make digital recordings. The small Tascam 60D that I use with my camera can buffer three seconds ahead. I didn’t look at the other one. Maybe you’ll get lucky.

Allen

From: Richard Prosser
Sent: Tuesday, October 6, 2020 3:27 PM
To: Microcontroller discussion list - Public.
Subject: [CAUTION: Failed DKIM Test]Re: [EE] Looking for technique to record audio after level exceedssome value

T

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Re: [EE] Looking for technique to record audio after level exceeds some value

madscientistatlarge
In reply to this post by Dwayne Reid
You want to do it the same way bank and some other security cameras work.  Specifically, set up a circular buffer large enough for the maximum period you want to record.  The sound is continuously recorded but written over IF there is no sound.  If a loud sound is detected you transfer the contents of the buffer and a few more seconds of recording (as needed) to storage.  This way the buffer keeps being overwritten when there is no "Loud sound" (or whatever trigger you want).

I'd guess there's a problem with some part of the ignition system.  We had a NEW gas fired boiler and it stopped working after a couple of weeks, turns out it used a hot electric heating element to do the ignition and it was cracked (I troubleshot it with the manual and confirmed with meter, HVAC guy was clueless).  Sadly, in multiple times I've seen that most HVAC guys really don't understand how the systems work, it's a bit like how most auto mechanics can't diagnose electrical problems, even some who are otherwise excellent mechanics.  Other systems use a HV spark.  All high voltage gear has a high failure rate due to the voltage stress and the electrodes wear.  A mediocre HVAC guy might not realize that they can become intermittent, electric lighters have the same issue as the electrodes wear down.  Intermittent faults are hard for anyone to diagnose and it's tempting to blame the customer if you can't see it happening.

Had detonation issues at an apartment where I lived, another tenant ignorant of how it worked had increased the gas to the burner (ancient coal fired burner converted to natural gas, had valves to adjust the pilot and the burner) and the unburned fuel/cabon monoxide was going off in the chimney.  What was sad was that on their' way to the boiler they walked right by the thermostat for the whole house and didn't see it.  I've wound up doing maintenance on the heating systems several places I lived, including flushing out water that had gone black and mucky (it gets more corrosive as the chemistry becomes more unbalanced).  I mention the "turn up the burner" issue as it's another explanation, though it would imply the wrong "jets" in the hvac box which shouldn't happen.


Sent with ProtonMail Secure Email.

‐‐‐‐‐‐‐ Original Message ‐‐‐‐‐‐‐
On Tuesday, October 6, 2020 1:18 PM, Dwayne Reid <[hidden email]> wrote:

> Good day to all.
>
> I have a peculiar problem and I am hoping there is an off-the-shelf solution.
>
> 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
>
> ------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
>
> Dwayne Reid [hidden email]
>
> 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
>
> ----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
>
> http://www.piclist.com/techref/piclist PIC/SX FAQ & list archive
> View/change your membership options at
> http://mailman.mit.edu/mailman/listinfo/piclist



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Re: [EE] Looking for technique to record audio after level exceeds some value

Chris Smolinski
In reply to this post by Dwayne Reid

> On Oct 6, 2020, at 3:18 PM, Dwayne Reid <[hidden email]> wrote:
>
>
> 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 have a program that can do just this, but... it's Mac only: https://www.blackcatsystems.com/software/macintosh-audio-recording-software.html

It's not very resource hungry, if you have an old Mac in the basement it would probably work :)

Chris Smolinski
Black Cat Systems
Westminster, MD USA
https://www.blackcatsystems.com


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Re: [EE] Looking for technique to record audio after level exceeds some value

madscientistatlarge
I'd say you should probably find another HVAC company, they aren't all pathetic.  This is a safety issue both in terms of gas explosions and damage to the heat exchanger.  It takes very little damage to cause it to leak carbon monoxide, especially since it's already under thermal stress.  At the very, very least lots of CO detectors are called for in the meantime.


Sent with ProtonMail Secure Email.

‐‐‐‐‐‐‐ Original Message ‐‐‐‐‐‐‐
On Tuesday, October 6, 2020 4:28 PM, Chris Smolinski <[hidden email]> wrote:

> > On Oct 6, 2020, at 3:18 PM, Dwayne Reid [hidden email] wrote:
> > 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 have a program that can do just this, but... it's Mac only:https://www.blackcatsystems.com/software/macintosh-audio-recording-software.html
>
> It's not very resource hungry, if you have an old Mac in the basement it would probably work :)
>
> Chris Smolinski
> Black Cat Systems
> Westminster, MD USA
> https://www.blackcatsystems.com
>
>
> -----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
>
> http://www.piclist.com/techref/piclist PIC/SX FAQ & list archive
> View/change your membership options at
> http://mailman.mit.edu/mailman/listinfo/piclist



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Re: [EE] Looking for technique to record audio after level exceeds some value

Clint Jay
In reply to this post by Dwayne Reid
Many of the cheap dashcams have sound and record on a loop so you could
have video and audio?

On Tue, 6 Oct 2020, 20:19 Dwayne Reid, <[hidden email]> wrote:

> Good day to all.
>
> I have a peculiar problem and I am hoping there is an off-the-shelf
> solution.
>
> 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
>
> --
> Dwayne Reid   <[hidden email]>
> 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
>
> --
> http://www.piclist.com/techref/piclist PIC/SX FAQ & list archive
> View/change your membership options at
> http://mailman.mit.edu/mailman/listinfo/piclist
>
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Re: [EE] Looking for technique to record audio after level exceeds some value

Bob Blick-5
In reply to this post by Dwayne Reid
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 clip each time an event happens, sound and video. You can use audio level as an event. The recordings appear to be centered somewhere on the event, so you should get the full thing. If you put an SD card in the camera it also will 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 without an SD card it is quite useful, although it only stores 14 days of clips, maximum 1 per minute. "in the cloud".

$19.99 US plus shipping, comes with magnetic mount.

Friendly regards, Bob

________________________________________
From: [hidden email] <[hidden email]> on behalf of Dwayne Reid
Sent: Tuesday, October 6, 2020 12:18 PM
To: pic microcontroller discussion list
Subject: [EE] Looking for technique to record audio after level exceeds some value

Good day to all.

I have a peculiar problem and I am hoping there is an off-the-shelf solution.

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


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[EE] Looking for technique to record audio after level exceeds some value

Jason White-20
In reply to this post by Paul & Lynn Tyrer-2
I'd be tempted to use the phone as an internet connected webcam/microphone.
Steam audio/video from the phone and record it on the PC.

On Tue, Oct 6, 2020 at 3:43 PM The Tyrers <[hidden email]> wrote:
>
> I would use a Sd card based security camera, Records prior to sound and
during.
>
>
> > On Oct 6, 2020, at 3:18 PM, Dwayne Reid <[hidden email]> wrote:
> >
> > Good day to all.
> >
> > I have a peculiar problem and I am hoping there is an off-the-shelf
solution.

> >
> > 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
> >
> > --
> > Dwayne Reid   <[hidden email]>
> > 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
> >
> > --
> > http://www.piclist.com/techref/piclist PIC/SX FAQ & list archive
> > View/change your membership options at
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>
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Re: [EE] Looking for technique to record audio after level exceeds some value

James Cameron-2
In reply to this post by Bob Blick-5
I once used an OLPC laptop to record every minute to a separate file
and encode as MP3.  It was a quick hack using Linux shell scripting.

Then, to find the real-life event that I was looking for, I discarded
the smallest files.  The MP3 encoding meant that the real-life event
audio consumed way more disk space than ambient silence audio.

Lately I'm interested in bioacoustics recorders, to find the bird
species on my property.  It is a similar use case.

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Re: [EE] Looking for technique to record audio after level exceeds some value

Alan Pearce
In reply to this post by Clint Jay
> Many of the cheap dashcams have sound and record on a loop
> so you could have video and audio?

That was my thought too. If it could be mounted so the thump of the
'explosion' triggered the crash detector then the clip would not get
overwritten if left recording.

Would make an interesting court exhibit if there was a major 'bang'
resulting in emergency services callout, especially after multiple
complaints to the HVAC engineers :)

On Tue, 6 Oct 2020 at 23:50, Clint Jay <[hidden email]> wrote:

>
> Many of the cheap dashcams have sound and record on a loop so you could
> have video and audio?
>
> On Tue, 6 Oct 2020, 20:19 Dwayne Reid, <[hidden email]> wrote:
>
> > Good day to all.
> >
> > I have a peculiar problem and I am hoping there is an off-the-shelf
> > solution.
> >
> > 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
> >
> > --
> > Dwayne Reid   <[hidden email]>
> > 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
> >
> > --
> > http://www.piclist.com/techref/piclist PIC/SX FAQ & list archive
> > View/change your membership options at
> > http://mailman.mit.edu/mailman/listinfo/piclist
> >
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Re: [EE] Looking for technique to record audio after level exceeds some value

madscientistatlarge
It would also be good to save in case Damage showed up months after they "fix" it.  Nice to have proof it was abused due to whatever is going on.  I.e. if it the heat exchanger etc. fails just out of warranty.  Having seen how large some of those units are they clearly are not cheap.

I actually got to see one helicoptered onto a building in down town Denver around 6 AM and another later in the day on a stadium box in Boulder.  Considering they used a helicopter and it's high risk enough that they have an ambulance standing by and police to keep crowds far enough away (I was standing by the ambulance).  It was really something to see, tremendous level of caution including an emergency release on the cable in case the the pilot had to let it drop, presumably if there's too big a wind gust or some unforeseen issue (Bolder can have incredible winds, i.e. so windy it's hard to take a step forward against the wind!  Literally standing on one foot and nearly unable to fall forward for several seconds, I got back inside quickly!).


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‐‐‐‐‐‐‐ Original Message ‐‐‐‐‐‐‐
On Wednesday, October 7, 2020 5:42 AM, Alan Pearce <[hidden email]> wrote:

> > Many of the cheap dashcams have sound and record on a loop
> > so you could have video and audio?
>
> That was my thought too. If it could be mounted so the thump of the
> 'explosion' triggered the crash detector then the clip would not get
> overwritten if left recording.
>
> Would make an interesting court exhibit if there was a major 'bang'
> resulting in emergency services callout, especially after multiple
> complaints to the HVAC engineers :)
>
> On Tue, 6 Oct 2020 at 23:50, Clint Jay [hidden email] wrote:
>
> > Many of the cheap dashcams have sound and record on a loop so you could
> > have video and audio?
> > On Tue, 6 Oct 2020, 20:19 Dwayne Reid, [hidden email] wrote:
> >
> > > Good day to all.
> > > I have a peculiar problem and I am hoping there is an off-the-shelf
> > > solution.
> > > 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
> > > --
> > > Dwayne Reid [hidden email]
> > > 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
> > > --
> > > http://www.piclist.com/techref/piclist PIC/SX FAQ & list archive
> > > View/change your membership options at
> > > http://mailman.mit.edu/mailman/listinfo/piclist
> >
> > --
> > http://www.piclist.com/techref/piclist PIC/SX FAQ & list archive
> > View/change your membership options at
> > http://mailman.mit.edu/mailman/listinfo/piclist
>
> --
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> View/change your membership options at
> http://mailman.mit.edu/mailman/listinfo/piclist



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Re: [EE] Looking for technique to record audio after level exceeds some value

Nicola Perotto
In reply to this post by Dwayne Reid
Hi Dwayne & all,

On 06/10/2020 21:18, Dwayne Reid wrote:
> Good day to all.
>
> I have a peculiar problem and I am hoping there is an off-the-shelf solution.
>
...
> IBM compatible Shareware or paid Android app is just fine.
I would use a Raspberry PI Zero W with an USB microphone, recording connected to
the WIFI LAN.
Oh, it's a Linux but the duty is so simple...
After this you can analize the file audio like others suggested.
      Nicola

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Re: [EE] Looking for technique to record audio after level exceeds some value

James Cameron-2
On Wed, Oct 07, 2020 at 02:28:51PM +0200, Nicola Perotto wrote:
> I would use a Raspberry PI Zero W with an USB microphone, recording
> connected to the WIFI LAN.  Oh, it's a Linux but the duty is so
> simple...  After this you can analize the file audio like others
> suggested.
>       Nicola

I agree.  Bioacoustic studies use this combination often.  There are
also USB microphones integrated with a USB connector, about 22 x 18 x
7mm.  Power the Pi from a USB battery.  Reach out to it with SSH over
WiFi at about the time the event is due, or was just heard.

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Re: [EE] Looking for technique to record audio after level exceeds some value

madscientistatlarge
It would likely help if you can point the camera towards the ignition area so that the specific problem is more obvious and documented, as well as establishing that the noise didn't come from somewhere else nearby.  Besides helping prove to HVAC people that there is a problem, it should get you an HVAC guy who has a couple more clues.  It is really hard to diagnose cross specialty issues.  Some people are much better at trouble shooting than others in any case.


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‐‐‐‐‐‐‐ Original Message ‐‐‐‐‐‐‐
On Wednesday, October 7, 2020 2:57 PM, James Cameron <[hidden email]> wrote:

> On Wed, Oct 07, 2020 at 02:28:51PM +0200, Nicola Perotto wrote:
>
> > I would use a Raspberry PI Zero W with an USB microphone, recording
> > connected to the WIFI LAN. Oh, it's a Linux but the duty is so
> > simple... After this you can analize the file audio like others
> > suggested.
> >      Nicola
>
> I agree. Bioacoustic studies use this combination often. There are
> also USB microphones integrated with a USB connector, about 22 x 18 x
> 7mm. Power the Pi from a USB battery. Reach out to it with SSH over
> WiFi at about the time the event is due, or was just heard.
>
> ---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
>
> James Cameron
> http://quozl.netrek.org/
>
> ---------------------------------------
>
> http://www.piclist.com/techref/piclist PIC/SX FAQ & list archive
> View/change your membership options at
> http://mailman.mit.edu/mailman/listinfo/piclist



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Re: [EE] Looking for technique to record audio after level exceeds some value

Justin Richards
In reply to this post by Dwayne Reid
How far apart are the ignition events,

VLC has worked well to quickly and cheaply get audio from one place to
another via a network where it can be saved to file and/or monitored as
required.

I used VLC to stream UHF radio whenever it was keyed so it could be
monitored locally and 100kms away at a remote site.

VLC is handy as it works on many platforms and is somewhat uniform to
configure.

It is currently being used to reliably stream 4 radio stations
(received via satellite) to VLC running on RPi's, Windows and Linux based
PC's.



On Wed, Oct 7, 2020 at 3:19 AM Dwayne Reid <[hidden email]> wrote:

> Good day to all.
>
> I have a peculiar problem and I am hoping there is an off-the-shelf
> solution.
>
> 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
>
> --
> Dwayne Reid   <[hidden email]>
> 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
>
> --
> http://www.piclist.com/techref/piclist PIC/SX FAQ & list archive
> View/change your membership options at
> http://mailman.mit.edu/mailman/listinfo/piclist
>
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