Ultrasound Sound Transducer for underwater purpose

[NPB777]

Presently I am working on Underwater Acoustic Wireless Transmission. I desire to measure water parameters at the bottom of the surface of the water and then pass it to the water surface using Ultrasound. There will be a buoy at the surface which is half submerged and half floating. The floating part will have the receiver. Desired data rate is around several tens of kbps. What are various Transducers available for this purpose to make a prototype with Arduino? HC SR 04 is the only easily available Ultrasound Transducer available at my place. But will it work underwater? Also suggest me good open source simulators which can satisfy this need?

 

[c_mitra]

First you need to ensure that the transducer is in full contact with the water.

What do you mean by "water parameters at the bottom of the surface of the water"

What kind of depth (signal and reflection return), power and frequency you are planning to use?

These transducers are piezoelectric and they must be in contact with the water body for proper signal transduction.

 

[FvM]

"several tens of kbps" with transducers that have only a few kHz bandwidth? Would require sophisticated modulation methods and good signal-to-noise ratio (read about Shannon-Hartley Theorem https://en.wikipedia.org/wiki/Shannon–Hartley_theorem)

 

[Warpspeed]

I know that at least with medical ultrasound, attenuation through any medium rises quite sharply with frequency.
As pointed out above, your required bandwidth of several tens of Kb per second is pretty unrealistic if you also require significant range, and a narrow ultrasonic beam cannot be very accurately aimed and focused at both ends of the path.

 

[DNA Robotics]

Maybe look into the transducers used in fish finders and work with their frequency. The ones for deep water use a different frequency than those for shallow water.

 

[FvM]

Besides intended data rate you should talk about range. Ultrasound attenuation in water isn't high but increasing with frequency. Most echo sounders are operating in the 100 - 200 kHz range and achieve several 100 meters.

Air ultrasound transducers are designed for a completely different acoustic impedance than transducers working with liquids.