A GENERAL-PURPOSE AUTONOMOUS TRANSMITTER AND RECEIVER SYSTEM FOR UNDERWATER ACOUSTIC EXPERIMENTS

A versatile multifrequency, multi-purpose acoustic transmitter and rec eiver system has been developed and used to measure low frequency acou stic backscatter from the ocean surface, The instrumentation is genera l purpose in that all signal and sample parameters are selected by sof tware and a variety of transmission, scattering and reverberation expe riments are possible without hardware modification, The system is batt ery-powered and self-contained for remote and unattended operation for periods of months, depending upon the experimental parameters that af fect power and tape consumption, The main features of the system are: a high-powered broadband set of acoustic sources-with center frequenci es of 100, 200, 400, and 800 Hz, programmable output signal types, a 6 4-element vertical hydrophone array, fifty gigabytes of data storage c apacity, dynamically-tuneable band pass filters and variable sampling rates, high power microprocessors for in situ signal processing and in dependent subsystems for recording mooring depth and inclination, The system has been used in surface backscattering experiments at sea and results that demonstrate the capability of the system are presented an d discussed.