| a sonar instrument that uses echolocation to measure depths under water. |
| echo sounder n. A device for measuring depth of water by sending pressure waves down from the surface and recording the time until the echo returns from the bottom. |
echo sounder
device used on ships to determine the depth of water by measuring the time it takes a sound (sonic pulse) produced just below the water surface to return, or echo, from the bottom of the body of water. Sonic depth finders are in operation on practically every important class of ship, naval and merchant, and are also used on small craft.
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