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I am curious if anyone has had any experience building an acoustic recorder from a small, cheap computer like a Raspberry Pi. I have a detection algorithm I wrote in Python and I know can run on an rPi, but I am unsure about the practicalities of building an enclosure, adding appropriate memory, and a sound card.

I know that for bat work there are things like the Bat-pi that employ off the shelf parts, like these from Dodotronic. And of course the AudioMoth is the same kind of idea. But these are all for terrestrial work.

For a test, I'd like to deploy a raspberry pi set up at say 10 m for a week, recording detection events at 512 kHz. Does any one have experience with this?

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I have experience with custom designed autonomous underwater recorder that uses an ARM7 microprocessor and is programmed bare-metal (all SW is compiled from source). It is working fine, but due to the tight package, I have to solve still some digital-analog interference issues.

Over all, it is rather easy, but nowadays the electronic component market is empty.

problems I encountered:

  • digital interferences into analog part of recorder
  • failing of microSD cards ( brand-new 1 TB disks)

I'm confident that these problems are solved soon.

Edit: my actual configuration is 6-hydrophones at 96 kHz, but I could via SW configuration go up to 2 hydrophones at 768 kHz, but then saving data to disk needs some attention. Obviously, performance depends on ADC and implementation constraints (like disk space and battery availability)

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  • $\begingroup$ Great details. Thank you. What sample rate are you recording at? When I've built something like this in the past I was looking at whistles and only going up to 96 kHz. I'm worries about the quality of the recordings in the higher frequencies, or overloading the compressor. $\endgroup$
    – etgriffiths
    Commented Jul 8, 2022 at 17:24
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    $\begingroup$ It would be really cool to see a blog post or something on this system :) $\endgroup$
    – nedlrichards
    Commented Jul 8, 2022 at 18:32
  • $\begingroup$ Let me see what I can do $\endgroup$
    – WMXZ
    Commented Jul 8, 2022 at 18:50
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I've no personal experience, but the POSEIDON recorder described in this paper uses a Raspberry Pi based recorder for marine deployment:

https://dl.acm.org/doi/pdf/10.1145/3196709.3196752?casa_token=g7y0dUUmJpkAAAAA:_9rHM_zZDxABB9PEn8LBBRhSKt_t7v41XHPzJ6fwd7gm75x5XjMesfVnZLGYtc-7-yyXXaE5erSd

Would that be suitable?

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    $\begingroup$ Oh wow! That's not quite what I'm looking for as they are still connected to the boat and have the electronics at the surface (I've built that, but not nearly as well!). I'm looking for something that could be used and left longish term. $\endgroup$
    – etgriffiths
    Commented Jul 8, 2022 at 15:52
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I know of Gregoire Lauvin located in Aix-en-Provence, France who designs recorders from scratch and made hydrophone+live stream boxes using Rasberry pies. You can find a lot of info on his website such as how to build an hydrophone (https://locusonus.org/wiki/index.php?page=Hydrophone.en) and also how to work with the RasPi (http://locusonus.org/streambox/). Hope you can find some interesting info there.

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  • $\begingroup$ Great resource, thx! $\endgroup$
    – etgriffiths
    Commented Jul 16, 2022 at 17:39
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I have two short responses, hope these are ueful:

  1. Have you seen the Hydromoth (underwater version of Audiomoth in a waterproof housing)?

  2. I think the key thing is deployment of the sensor itself, rather than the processing unit. Can you mount your RasbPi above the water (i.e. on a buoy/raft), and just connect to a cabled hydrophone, which is submerged to 10m depth?

Thanks

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    $\begingroup$ Hey Carlos! I've done that before for smaller deployments. However, for safety, I'd like to have the whole thing under water, so it doesn't interfere with mariners. $\endgroup$
    – etgriffiths
    Commented Jul 11, 2022 at 23:06
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    $\begingroup$ @etgriffiths I'll second the Hydromoth...works fine on a mooring and kinda hard to beat for the price. There's a GroupGets going on right now: groupgets.com/campaigns/1048-hydromoth $\endgroup$
    – CosmicSpittle
    Commented Jul 12, 2022 at 22:34
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    $\begingroup$ My issue with the hydromoth is that I want to run my own script, not a predetermined broadband recording or detector. $\endgroup$
    – etgriffiths
    Commented Jul 16, 2022 at 17:38

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