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Underwater communication using ultrasonic

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paulmdrdo

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https://people.ece.cornell.edu/land...p295_lf298/kp295_lf298/kp295_lf298/index.html

I found this link about acoustic modem. I'm wondering if this can be modified for use in simple underwater communications. My plan is that instead of using speakers and microphones I will use an underwater transducer and a hydrophones in transmitting data like a simple "HELLO WORLD" text. From the link above what are the parts of the design should I modify to be able to do an underwater data transmission?
 

It will work as it is. The design uses two tones and tone detectors, all you have to do is use one tone for '0' and another tone for '1'. Technically, you can use just one tone and key it on and off but it opens the possibility of stray sounds being misinterpreted. The data rate would be quite low though, probably 100 Bauds or less due to the time the tone detectors need to reliably confirm the presence of the appropriate frequency. For ideas, look up "RTTY" which uses the same principle but a slightly different coding system which you can ignore.

Brian.
 

Good day Sir! Actually what I want to do is to build an underwater data transmission system using ultrasonic. The set up would be: I have a simple "HELLO WORLD" text message that I will send acoustically to the receiver end that would then be displayed on an LCD. Can you tell me the hardware that I would need to do this? Or at least show me the block diagram for the set-up I mentioned above? This set-up will be inside a 2 meter long and 0.5m wide aquarium. THANKS!
 

Over such short distances and in an enclosed environment, all you need is your transmitting end to send a serial data stream (from it's UART) to key an oscillator on and off. You may be able to do this by generating the tone in software or MCU hardware to avoid using an oscillator. Feed it's output to a waterproof loudspeaker.

The receiving end should have a tone detector (suggest NE567 IC) which will produce an output telling whether a tone is present or not. When fed from a waterproof microphone it should recreate the serial data stream just as it was sent. Use that to feed a UART and from there to your LCD. It is fairly trivial task.

Brian.
 

Hi,

Why acoustic. Isn't IR much easier?
What's the benefit of acoutsic?

Klaus
 

KlausST said:
Hi,

Why acoustic. Isn't IR much easier?
What's the benefit of acoutsic?

Klaus
Click to expand...

Hello! This project would serve as a proof-of-concept of some sort for the AUV project of our school. Our group is focused more on the hardware part of the system. Do you know any references I can read about the hardware part of an acoustic comms? By Hardware, I mean the transmitter, receiver part not invlolving the digital platform. We want to show that we can transmit a signal underwater at some distance acoustically and that's basically it. The system that we plan to build should be tested independently from the remaining system. Thanks!
 

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