Clipped‐Digital Technique for the Sequential Processing of Sonar Signals

A signal‐processing technique for pulsed sonar systems is described in which the sound field is treated as a series of point targets or highlights. Only the phase information of the narrow band echo signals is utilized, the outputs of the individual transducers being infinitely clipped and encoded directly in digital form. Subsequent operations performed on these numbers have the effect of steering the system to point in the direction of the strongest signal which illuminates the array at that particular instant. A linear phase‐difference pattern is looked for, and numerical parameters are extracted that are a measure of how closely the received pattern matches the expected one. Signal detection is achieved by a hierarchy of thresholds operating sequentially on these parameters. Field trials of an experimental equipment in a shallow reservoir are described, and the results and measurements presented. The technique has also been analyzed and simulated on a digital computer, and a quantitative comparison between the efficiency of the proposed system as a signal processer, with that of conventional amplitude methods, is included.