Research And Realization Of High Frequency Doppler Measurement System To Current Relatively

Doppler Velocity Log is a precise instrument to supply navigation information fop ship. It can measure ship's velocity to navigate for ship. It's difficult to obtain the information about precise velocity relatively to the seabed in the real environment. In fact, we can make use of acoustic Doppler to measure velocity relatively to the current layer in order to overcome the difficult problem.The thesis researches about narrow-band high frequency signal to measure velocity relatively to the current layer. Research and design of digital signal processing system is completed mainly in the thesis. The contents of the thesis include the theory of current measuring, the result of arithmetic simulating about band-pass filter, integer-coefficient filter compared with the result of DSP processing to the real signal, design of hardware system, program of software and analysis of experiment result.In the hardware aspect, TI's low-power fixed-point DSP is the signal processing center of Hardware system. Three chips DSP have different functions. One controls the transmitter and communicates with others through Mcbsp, calculates the velocity, stores data and communicates with host computer by universal asynchronous receiver/transmitter. Two DSPs are to collect data from four routes signal, detect signal and compute frequency. ALTERA's CPLD takes charge of system logic, including producing synchronization signal, relay controlling signal and band testing signal. Two chips of serial interface Analog-to-Digital converter are responsible for signal conversion. It can improve work efficiency of system hardware through reducing the single processor pressure.Software is programmed to develop DSP basing on platform of hardware which makes arithmetic and controlling come true. Module design is used in programming. The system can work in the different modes. DSP can change CPLD's work state to correspond with system. That can not only strengthen logicality, but also make program more efficient and flexible.The system of measurement is validated through experiment on the songhua lake, including design scheme feasibility, hardware stability and arithmetic rationality, and the results as we expected well.