I have an HC-SR04 ultrasonic sensor that seems to work pretty well sensing solid objects, but also does a good job detecting the surface of a tank of water so not sure how I would work this underwater (besides keeping it dry).The commercial units just press the US transceiver down on the surface of the ice. If you did it from the surface, you'd have less to worry about waterproofing it.I also thought about a magnet at the bottom with a Hall effect sensor above the ice but I have no experience with these so don't know if you could get a field strong enough to measure.The neodymium magnets you can get now are VERY powerful.
I also thought about a magnet at the bottom with a Hall effect sensor above the ice but I have no experience with these so don't know if you could get a field strong enough to measure.
I was thinking that the interface would only be detectable if you were going from water to ice...of course now it occurs to me that ice is actually less dense than water. So analagous (sort of) to going from air to a solid object like a wall.Would US reflect from and interface (change in density) or just going from lower to higher density?
Wow, those 5 Mhz transducers probably cost more than the skating rink. One thingabout using sonar is, you'd no doubt have to build the electronics yourself, and do measurements along the lines of regular submarine-type measurements - ie, analyzesignals on an oscilloscope and look for transition blips at ice-water and ice-air boundaries. Not nearly as easy as simply reading a Ping sonar.My latest idea involves using a clear plexiglass cylinder, place vertically in the pool, so you can look inside and see the ice boundaries. Or for more "elegance", read theboundaries using some electronics means.
Can you think of a way to read the boundary electronically?