 Sonar

Sonar uses sound propagation and reflected signals to detect objects or measure distances. Upward-looking sonar can record sea-ice draft along a moving platform's track; beam width, return selection and processing affect the inferred profile.

"Sonar" refers to a technology used for detecting and locating objects underwater by using sound waves. The term is an acronym for "Sound Navigation and Ranging." Sonar systems work by emitting sound pulses (or pings) into the water and then measuring the time it takes for the echoes to return after bouncing off objects, such as the sea floor, submarines, or schools of fish.