Sidescan sonar detection performance with PRN coded signals

A sonar transmission signal that has enhanced the operation of conventional 50 kHz depth sounders in noise-limited environments has been applied to a sidescan sonar application where the acoustic background is dominated by reverberation. By transmitting a pseudorandom noise (PRN) source pulse with a high bandwidth-time product, and detecting the returned signals by cross-correlation with the source waveform, the potential processing gain is greatly increased and high resolution in both time end frequency is achieved. In a sidescan application, the depth-sounder transducer was aimed horizontally and driven with a variety of PRN coded and uncoded source signals. An artificial target array was deployed on the bottom at a shallow water test site to simulate a cluttered background against which detection performance for pre-existing bottom targets could be evaluated. Detection performance of the PRN coded signals has been found superior to all uncoded signal types both for cluttered and uncluttered backgrounds