Continuous Tone Underwater Reverberation

Abstract

Continuous tone underwater reverberation is the signal observed when the transmitting and receiving transducers are in linear motion, the transmitter is operating at a single frequency, and no major reflecting bodies are in the beam paths. This reverberation has been measured as a function of frequency for ocean depths of 9.5 to 85.7 meters, at transducer speeds up to 7.5 meters per second, and for various sea states. The techniques for measurements are described, and some typical reverberation spectra are shown. The spectra are shown having maxima at approximately the frequency corresponding to the Doppler shift caused by the transducer motion. The spectra are asymmetrical about the maximum, with the general reverberation level decreasing with increasing depth and decreasing sea state.