A digitally controlled acoustic system for measurement of ocean depths by echo sounding is described. This automatic digital depth (ADD) system was developed at W. H. O. I. to provide depth information directly to a shipboard digital computer. Automatic range gating prevents false depth readings from echoes returned from shallow, midwater reflectors. Readout is both visual, on a lighted digital display and electrical in the form of a binary coded decimal (BCD) output. The depth is read directly in fathoms based on 4800 feet per second sound velocity. Other units of depth may be used with little change in circuitry.