The Design And Implementation Of FPGA-based Underwater Acoustic Ranging System

Hydroacoustic ranging technology is very important part in sonar systems.Both acoustic positioning, tracking, navigation, and some water acoustic measurement mapping experiments, are inseparable from high precision underwater distance measurement. According to different ranging application environments, the measurement condition, measurement accuracy and measurement range and other requirements vary. This paper mainly designed a hydroacoustic ranging system for ship radiated noise measurement experiments,which requires a high ranging accuracy,and less impact on their ship radiated noise.Papers design and implement a synchronous clock underwater acoustic ranging system based on FPGA according to application requirements, including synchronization beacon transmitter and correlation receiver,with a high range accuracy, good anti-jamming performance, high emission efficiency, and small impact to the sound field. System synchronization is implemented through a of high stability OCXO. The beacon transmits wideband pulse using PWM modulation. The receiver detects ranging pulses through digital matched filter implemented by FPGA, and then sent the time delay data to the computer through SOPC for the distance conversion and interface display. FPGA processor is a low power Cyclone III series. The program mainly by the VHDL hardware description language, and using FPGA for DSP algorithm is one of the difficulties. The design of SOPC greatly improves the integration of the system.Finally, the ranging system was tested in the pond experiments. The wideband pulse emitted by the beacon, and the performance of matched filter in the receiver are desirable. Ranging experiment data were recorded at close range and the results of error analysis show that the design of synchronous clock underwater acoustic ranging system basically meets the requirements.