An underwater sound velocity measurement device is used to determine the locations and measure the depths of objects underwater.
These sensors work by measuring the speed of sound waves underwater. It has a single piezo sensor on its front side. It sends an initial pulse, which is the start pulse. After the start pulse hits the opposite surface, it bounces back, and the piezo is affected by the pulse and generates a voltage. This is the stop signal. By measuring the time between the start and stop signals, the real-time sound velocity of the water is measured.