Whale listening NRF24L01 project questions

I find myself needing some advice. I’m working on a whale listening project. Humpbacks and Orcas occasionally travel by our cottage. I thought I’d like to make a wireless hydrometer that I could suspend underneath a buoy about 150 meters (line of sight) from our cottage. I’m using a piezo pickup for a mike, and it appears it will work quite well. I’m using a sound sensor which I’ve roughly tuned to the whale song frequency. I’ll also hook up a preamp.
What I’d like to do is connect the piezo mike (after preamp) to an Arduino (analogue?) and convert the signal to digital. Transmit it to the cabin using an NRF24L01, then receive it on an NRF24L01 ( I have lot of them from other projects) and feed it to the sound sensor which will sound an alert (AND) turn on audio (again I have lots of audio amps) so people can hear the sound (and go out and look for whales).
What my biggest problem is digitizing the audio from microphone. I don’t want to try and send it analogue. I’ve looked into the walkie talkie NRF24L01 projects and the audio quality if poor. I’ll need good quality data to trigger the sensor.
Any idea, or does anyone know of audio/digital projects I might be able to adopt?
Jeff

You need a fast Arduino with a lot of memory to digitize sound with decent quality. The Teensy series works well. I doubt that the NRF24L01 could transmit high quality audio data in real time, though.

Any circuitry exposed to a salt water environment has to be completely encapsulated in potting compound, or in an absolutely water and air tight enclosure, or it will corrode to green slime in just a few days.

thanks for that. I've already built an underwater camera for recroding, so I'm pretty good at salt water proofing electronics. It's dealing with digitizing the whale songs on the fly I need help with.

Interesting project. I'll second the vote for faster hardware: Teensy is good as mentioned, some of the Adafruit stuff is good too. It might actually be a good project for a Pi.

Since the sea is a noisy place, the trick is going to be isolating whale song sounds so that you can give the alarm.

An Arduino can digitise at no more than ~9800 sps, 10 bits, for a total data rate of 20 kB/s. That should be within the ability of a NRF24 to transmit even at lowest data rate (and longest distance), but it's not going to give you a particularly good sound quality.

If you want to do anything more analyses on the sound before transmission, I'd suggest you go for a Pi.

Thanks for the reply. If I get a decent digital signal I can set the frequency. The "whistle" switch is fairly close in frequency. The problem is getting a clean signal. I've debated about moving to a short range FM transmitter. But don't know too much about what's out there. If I have to switch to a raspberry pi that means new hardware and learning. Might look for something off the shelf to transmit/receive audio... any ideas?

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