Underwater Motion Sensing using Ultrasonic Sensors

Community General Discussion
1

Hello,
I am currently developing a project which involves detecting a human underwater. I am doing this using ultrasonic sensors and Arduino Uno as the board. But the sensor I am using is not giving me great results. Can anyone suggest and underwater ultrasonic sensors or any other approach by which i can detect underwater humans at a low cost.

Thank you.

2

The speed of sound is very different through water - have you allowed for that?

...R

3

Yes i had taken the speed of sound in water into account. But the sensor doesn't seem to work underwater. Can you suggest a good underwater ultrasonic sensor with wide detection range?

4

Yash16:
But the sensor doesn't seem to work underwater.

That is very very different from the statement in your Original Post "the sensor I am using is not giving me great results"

And, sorry, I have no knowledge of underwater sensors.

...R

5

Robin2:
The speed of sound is very different through water

...as is the density of the medium.

6

Yash16:
Hello,
I am currently developing a project which involves detecting a human underwater.

Look for bubbles.

7

Yash16:
Can anyone suggest and underwater ultrasonic sensors or any other approach by which i can detect underwater humans at a low cost.

Are the underwater humans trying to avoid detection? Are they even alive? Could they carry flashlights? What distance?

I bet a fish finder would work.

8

The standard ultrasonic senor has to be out of the water to work such as in a water proof case. The sound will reflect off of the case or possible surface of the water. Also, I have found the sound is attenuated of muffled clothing and the sensor reads 0. Assuming it travels through water this is something to think about.

I would suggest a laser beam/light senor. However, standard red lasers are reflected by water. Maybe you can be a little more specific on the purpose of this.

9

I'm not clear what you have done or want to do but you need to avoid any air-water interfaces or you will get zero signal back. This means your transducer needs to be either submerged in water or, possibly, in an electronics-safe gel of some sort to provide acoustic coupling. Maybe a conformal coating would work but I will leave that for you to play with.