A new sub-bottom profiling sonar using a non-linear sound source

This paper describes a sub-bottom profiling sonar based on a non-linear sound source. The primary frequencies are centred around 38 kHz giving a difference frequency in the range of 1¿7 kHz with beamwidth from 10°¿5°. Using the relative broad bandwidth of the system the transmitted signal can be phase-modulated and the received signal compressed by correlation technique. The design considerations, specifications and performance of the system are outlined and the first results from field experiments are included.