ACOUSTIC DYNAMIC RANGE

A SINGLE ACOUSTIC SENSOR CHANNEL OF A HIGH DYNAMIC RANGE SONAR PROCESSING SYSTEM IS PROPOSED FOR DESIGN CONSTRUCTION AND TEST. THE HIGH ACOUSTIC DYNAMIC RANGE IS PROVIDED BY AN ACOUSITIC SENSOR (HYDROPHONE), A LOW GAIN (20DB) AMPLIFIER AND AN OVERSAMPLED SIGMA DELTA MODULATOR OF 18 (108DB) BITS OR 20 BITS (120DB). TWO DIFFERENT MODULATORS ARE PROPOSED FOR TEST, A MONOLITHIC 18 BIT ENCODER WOULD BE TAKEN TO AN APPROVED NAVY ACOUSTIC TEST FACILITY WHERE HIGH AND LOW LEVEAL ACOUSTIC PRESSURES WOULD BE APPLIED TO THE SENSOR IN WATER. THE OVERSAMPLED OUTPUT OF THE ENCODER WOULD BE FILTERED AND DECIMATED AND ANALYZED BY AN FFT/PC ANALYER AND THE SENSOR CHANNEL TESTED FOR LINEARITY AND TOTAL HARMONIC DISTORTION. A REPORT WILL BE WRITTEN.