The Key Technology Research Of Forward Looking Sonar Transmitter Array

With the development of marine resources exploitation and deepening of seaborne trade, the technologies associated with marine cause more and more attention. Our country has vast coastline and many ports, it is a developing maritime power, the development of marine exploration technology has a huge role in promoting the marine economy of our country. Forward-looking sonar is a high efficiency and precision measuring underwater environment measurement equipment, is widely used to protect water traffic safety and underwater environmental resources exploration, construction of port terminals, inland water resources survey, river dredging and other fields. The main research contents of this thesis are as follows:Investigation of the current development status of forward looking sonar and its working principle. Started with the principle of beamforming, this thesis analyzed the key technologies of sonar array. Aimed at arrays sidelobe problems, it analyzed the traditional amplitude weighting method, and presented a new sidelobe suppression method based on density weighted which is suitable for small size sonar array.Aimed at the specific requirements of forward-looking sonar system, analyzed the characteristics of power amplifiers, and finally chose the transmitter design scheme based on class D power amplifier. According to the defects such as structure complexity, amplitude and phase controlling that exposed in this scheme, this thesis presented a modified form of PWM controlling signal. Using MATLAB Simulation, the calculation formula of the relationship between the amplitude of ultrasonic signal and PWM pulse widths have been given.Designed the hardware circuit using FPGA as the control core, ultrasonic driver chip HV7350 as power amplifier core, write the FPGA program and the system function is verified through experiment. Provided theoretical reference for the development and research for the forward-looking sonar.