Currently, I am working on a project that would help blind people swim in swimming pools. To do this I thought of incorporating an ultrasound sensor on top of a swimming cap or something like that, to notice them they are near a wall and need to turn. The problem is I cannot find ultrasonic sensors that would work properly under water. Can you recommend me one? Also, is the ultrasonic sensor the right choice, or should I be looking at another sensor?
google sonar and fish finder,
remember to preface your search with arduino
arduino fish finder
arduino sonar
alas, you will have to sort out the junk because people do not understand the meaning of words.
the vast majority of the results will be for air based units.
you need to find a sensor taht can be used underwater.
waterproof does not man for use underwater.
If it's on top of the swimming cap, it'll most of the time be out of the water.
wvmarle:
If it's on top of the swimming cap, it'll most of the time be out of the water.
If it is on top of a swimming cap, it'll be underwater at least 80% of the time for any competent swimmer, regardless of stroke.
The way the Dutch learn to swim (which is based on being confident in the water and self rescue, rather than going as fast as possible) the head is kept out of the water most of the time.
What do you see in the water while swimmers are swimming in the pool? TURBULENCE! This will give erroneous echo every time. Can you program to filter these echos out of the wanted echo returns? Probably not.
Paul
The problem is I cannot find ultrasonic sensors that would work properly under water.
You can certainly buy them (e.g. fishfinders), but they don't work out of the water, and there don't seem to be any available that are Arduino compatible.
The transducers typically require a 200-400V AC signal at 100-300 kHz to send a "ping".
Thank you all for all your answers. As it seems this project is unfeasible with my current budget, so I guess I have to think of another project not on water this time.