Use of a hydrophone on the ROV?

General Discussion
1

Hello all,

I have been wanting to install a hydrophone on my BR ROV and wonder if anyone else has experimented with one?
My purpose is to “listen” to the distinct sounds of the Vaquita porpoise that is the rarest of marine mammals (about 10-12 left on the planet) that are only found in the Upper Gulf of California (Sea of Cortez). They emit sound “clicks” between 120-150 kHz which is considered high frequency and above our hearing.
It would seem that I could use a hydrophone that has a pre-amplifier and filters that just detect the clicks in the above range, then analyze the collected data.
If anyone has experience with this, love to hear it. Thanks.

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2

Looks like I will try using a DAQ/HAT on a Raspberry Pi mounted inside a separate enclosure. This won’t give me real-time monitoring of the sound data, but a passive collection of data.

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3

Hi Mike -
I saw your email on this topic, but just to share publicly, ACbotics has many solutions that may be better for your application than the DIY approach!

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4

How about an approximate price?

5

I believe there are solutions available for less than $800, but I’d recommend reaching out to the vendor!

6

The University of Maryland has a program that uses fixed hydrophones in the Chesapeake for studying Dolphins. That may be a place to look further for more resources.

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But they are limited by the frequency range…up to 90 kHz. My project needs a hydrophone that can detect up to 150 kHz.

8

Maybe this option fits the application?

9

You do know how loud the BlueROV2 is, Right? You won’t be able to hear anything while the thrusters are armed. Even the stepper motor in the Ping360 sonar can be heard by my GoPro camera.

I own a Aquarian Audio H2a-XLR, but their hydrophones are only rated (tested?) up to 100 KHz.

Maybe you could e-mail them and see if their “scientific” version would work above 100 KHz even if it’s not officially rated for it. looks like there’s still some response above 100 KHz on the graphs.

Audio from mine of a dock splashing in the waves:

10

Great point @btrue !
We’ve seen customers doing research with the Blue ROV2 and hydrophones take a drive and drift technique. If the ROV is tuned to be very close to neutrally buoyant, you can drive some distance, disarm, and listen for a period of time. Tricky for sure!

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As I stated the sounds I am detecting are much higher frequency (120-150 kHz) that our hearing range. So I don’t worry about the thruster noise.

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Yes, very familiar with ST. They are passive only and are left in the water for days. Assuming it is still there (not stolen), need to take out the card and sift through lots of noise to find the signal of interest. Not going that route yet.

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Hi @bajaMike -
The thrusters likely emit pretty broad spectrum noise, I would not be surprised if some of it is in that range…
You may want to reach out to BlueIQ, their approach to machine learning with hydrophone data can make sifting through the recordings unnecessary…

14

Need to know what noise frequency those thrusters emit. Has no one from BR tested them?

Tried contacting the “woman owned company” (LOL) and got no response. They don’t seem legit to me.

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Sorry @bajaMike, we’ve not tested the thrusters for sound emissions - as you are finding doing so can be quite expensive and involved!

I can assure you BlueIQ is legitimate, they just may take more than 24 hours to respond, as they likely don’t have a dedicated support team as a start-up company.

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Well then, when I get my rig set up, will try and detect the thruster noise freqs.

17

This looks pretty cool…although maybe not quite to official product stage yet…

Aquatec Group Ltd - Aquatec’s Impactful Showcase at Ocean Sciences Meeting 2024

AQUATEC_-_First_Results_from_an_Innovative_Passive_Broadband_Marine_Mammal_Sound_and_Underwater_Soundscape_Recorder.pdf (aquatecgroup.com)