The Design And Implementation Of Buoy-based Underwater Acoustic Signal Processing Platform

The design of buoy-based underwater acoustic signal processing platform, which is a part of the buoy subsystem in one underwater positioning system to track the underwater targets, is discussed in this dissertation. This platform possesses the ability of processing signals from four different channels at one time including three signals from the vector hydrophone and one signal from scalar hydrophone. It takes charge of conditioning the analog signal, transforming from analog signal to digital signal, transmitting and processing digital signal, storing and calling back the acoustic data, and so on.The analog veneer plays a roll in analog signal conditioning. The analog signal is firstly changed from the differential to single-ended, secondly passed through the band-pass filter, then changed to differential, finally arrived ADC via optocoupler, which is used to isolate the analog circuit and digital circuit. The digital veneer is composed of DSP and FPGA, three DSPs take charge of computing, while DSP0 answering for processing the seeking target signal of underwater target, DSP1 and DSP2 uniting to process the navigation noise and transient signal .The FPGA takes charge of logic managing, including controlling the AIC33 and ADS8326 to transmit analog signal to digital by some sampling frequency, and passing the digital signal to relevant DSP by McBSP, and storing the effective acoustic data in NAND Flash memory at proper time.The dissertation mainly discusses the design and achievement of the NAND Flash controller. The controller processes the ability of both managing usual function of NAND Flash and achieving the management of invalid blocks, including the creation of original bad block table, the update of bad block table, as well as the avoidance of bad blocks, etc.