hello, I want to know if it exist a depth sensor module that can works with arduino. I'm interested in reading the distance from the surface. The arduino will be used underwater.
There are many pressure sensors that will work with an Arduino. You can measure the water pressure and calculate the height of the water column.
But the question is... the lecture will be accurate? because each water is different, I mean, some waters contain more salts than other and I don't know if this parameter will affect to the final lecture.
What degree of accuracy do you require?
+/- 30 centimeters or 50 centimeters at least
Wikipedia says seawater ranges from 1020 to 1029 kg/m^3 so the variation in density is less than 1%. If going from fresh water (1000 kg/m^3) to seawater the variation would be 2-3%.
1 Bar = about 10 meters of water. Slightly higher for fresh, slightly lower for sea.
If you measure absolute pressure in milliBar you get depth in 1/100 m (1 cm). That should be plenty accurate. Even centiBar accuracy is three to five times what you need.
How deep do you need to measure?
It's pretty accurate. The maximum depth I've to measure is about 10 meters, no more.