Design And Realization Of Signal Processing Software And Hardware For Dual Frequency Echo Sounder

Dual Frequency Echo Sounder(DFES) is a kind of single beam device used for measuring landform of seabed. Though its function is simplex, its performance is moderate, price is low, and it is convenient to use. So it is salable and welcome by vast moderate customers.The main task of the thesis is to design signal processing system of Dual Frequency Echo Sounder(DFES), including hardware and software. Specific circuit of the signal processing system was designed based on the analysis of working principle of Echo Sounder. Hardware was realized, based on which the DSP software was compiled. Finally systematic assembly and experiment were carried out and result of the experiment was analyzed.Circuit of the signal processing board was designed and specific solution of DSP software was decided. Signal processing software and CPLD software were compiled. Several signal forms can be selected, including CW pulse of different width, Linear Frequency Modulated signal and Frequency Hopped signal and so on. Two algorithms, front edge method and energy center convergence method can be selected to achieve the goal of depth measurement. Based on the discussion of several signal processing method, correlation and FIR filtering were selected to complete process of echo wave. Concerning the communication between DSP and computer, the idea of ping-pang operation was applied, which increased efficiency. In order to make the change of depth range more stable and dependable, variable protecting depth was added when the depth range was to change. With reference to CW pulse of different pulses, corresponding band pass FIR filters were designed. Concerning different depth range, corresponding blind range and transmitting power were decided.Signal processing software was compiled by C and assembly language. Result of the experiment indicated that hardware system was stable and software ran normally. The function of depth measuring was achieved. The task of the thesis has laid a foundation for further improvement.