Earlier quoted context omitted.
It prevents the fire from quickly moving through the building...
Also, people.
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Fire alarm audio detection, using FFTs and Go
41–50 of 51 posts
Re: Fire alarm audio detection, using FFTs and Go
#42Earlier quoted context omitted.
This is the kind of discovery that settles all debate in my mind that I could have ever been an electrical engineer, or any kind of mathematician.
This is pretty much how I feel every time delving into FFTs. Like, I get the concept, but something in my brain just shuts off when it comes to actually trying to grok it. I do however very much appreciate those that have created software where I just provide --input and they handle the rest.
I also have trouble wrapping my head around all of this, and complex numbers, for that matter. Never mind that I'm employing this stuff all the time in GNU Radio.
Re: Fire alarm audio detection, using FFTs and Go
#43Re: Fire alarm audio detection, using FFTs and Go
#44Funny, I was just thinking about building something like this since I bought a z-wave smoke alarm listener and it does not work with my first alert system and it really annoys me. It can't be that hard, right? Even something that just detects extremely loud sounds would be useful despite false positives
The First Alert RM4 is an officially supported first-party product and costs $25. It really ought to work reliably.
Re: Fire alarm audio detection, using FFTs and Go
#45you dont need a FFT you can use a Goertzel band pass filter
100% great suggestion. I found this solution the hard way, by hand, on paper, a few weeks before learning this algorithm already existed. Reminded me that a large percentage of efficient engineering is just knowing what tools you have available off the shelf.
The algorithm I figured out was mostly equivalent, though about 3x slower than implementing Goertzel. In my use case, it was already a win hitting the product requirements, but implementing Goertzel allowed background functionality to operate better while capturing data.
Re: Fire alarm audio detection, using FFTs and Go
#46It is also quite useful to know exactly which alarm triggered. It would seem it is not feasible to have a DIY system to implement this
Regular interlinked alarms don't really allow this, since if one triggers they all alert.
You could potentially do this with "smart" alarms, or a traditional alarm system like DSC with each detector on its own zone (the main alarm siren sounds rather than all the individual units). I'm not sure how or if this complies with current building codes though, which I believe require an audible alarm in every bedroom (which normally means an interlinked unit in every room).
Re: Fire alarm audio detection, using FFTs and Go
#47Re: Fire alarm audio detection, using FFTs and Go
#48Just solder a wire in there somewhere. Even if you knew absolutely nothing about electronics, 50 trial and error solder points sounds like less work.
It'd be even simpler to set up a piezoelectric sensor or a mic right on the device. If the device is vibrating, there's a 99.9% chance its going off.
Re: Fire alarm audio detection, using FFTs and Go
#49Just solder a wire in there somewhere. Even if you knew absolutely nothing about electronics, 50 trial and error solder points sounds like less work.
Then what? Run 50-200 feet of wire back to an Arduino? Or buy an Arduino and provision it for every smoke detector in the house? How do you power them? Another wall wart? If audio fingerprinting can identify Miley Cyrus in background noise in a crowded bar, certainly it can identify the symmetrical piercing monotone of an alarm.
An arduino BLE, 18650 battery will probably run you about 50 bucks (retail, one-off). From experience, that will run for at least 4+ years in low-power mode -- maybe even decades. Announce a BLE service with the alarm status.
Re: Fire alarm audio detection, using FFTs and Go
#50There's a physical product that implements the same idea [1]. I'm not sure how it actually works (presumably there's a patent somewhere, is there an alternative solution?) but it's quite a magic feeling to hear the fire alarm go off and the doors independently close by themselves. If you're in a building that uses these, you can test yourself by playing a recorded fire alarm sound - they work on quite a few different…
> it's quite a magic feeling to hear the fire alarm go off and the doors independently close by themselves Closing doors on a fire alarm seems hilariously cruel.
These are installed on doors that have an auto-closer anyway. They deter people from propping them open permanently with a wedge or a chair.