[AudioI] Opensource Shot Spotter project

[Matt Flax]

OK, sounds like a project in sound source direction detection.

You can start with two channel applications with the stereo soundcards. 
For more then two channels, you will need to migrate to the Octo 
soundcard. It can capture up to 6 channels of audio. What do you think 
if this idea ?

The Octo has the input differential lines broken out and 5v power lines 
as well. You can see a KiCad starting project for building your own 
multi microphone board here : 
https://github.com/Audio-Injector/AudioInjector.Octo.template/blob/master/AudioInjector.Octo.sch.pdf

There are other octo related projects there as well. For example the RCA 
preamp project shows you an example of interfacing single ended inputs, 
or you could use the electret microphones in some differential 
signalling setup with a suitable opamp or IC generating microhpone 
amplification.

In the past I have built an electret microphone supply using an adum5000 
IC (to give a clean low power reference) followed by a 2.5v 1117 LDO 
regulator, which will generate the required electret power supply.

For ensuring synchrony on the input channels, you will want to use one 
of the standard techniques people use to ensure synchrony. One example 
is to use this code to align input channels and avoid any channel 
swapping : 
https://github.com/flatmax/gtkiostream/blob/master/test/ALSAFullDuplexMinScan.C#L65-L77


Matt

On 6/3/22 15:17, mfreeman451 via People wrote:
> Myself and a few others are interested in building an Opensource "Shot
> Spotter" implementation. I ordered a few of the the zero soundcards to
> get started but I'm wondering how hard it might be someday to make
> some custom PCBs that have 4 mic inputs?
>
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