The Research Of Navigation Parameter Telemetry Technique Of Underwater Object

Navigation parameter telemetry technique of underwater object is a kernel technique for transmitting message between systems like underwater vehicles and cable-free underwater robots. This thesis is engaged in navigation parameter telemetry technique used for testing high speed object in shallow water with multi-path condition by analyzing the characteristic of underwater sound path. It concerns in Doppler compensation and underwater telemetry signal mod-demod technique researches by theory analyze and simulation. Then the signal processing prototype was formed and had been tested on lake.In this thesis, we concentrated on the transmit model of signal path in shallow water. The model was established based on sound line theory by analyzing the multipath character of the underwater acoustic signal path. We simulated the transmit character by Matlab, studied the frequency select character and the variation in SMR with the distance, and analyzed the transmit track of sound in four seasons.The Doppler compensation technique for high speed object is researched and an effective compensation scheme was proposed. That is to match filtering the linear modulate sync signal, realize the Doppler frequency shift estimation based on frame length measurement, and then the linear interpolation is used for the Doppler compensation. It had been demonstrated by simulation and test on lake that the frequency shift compensation precision is in 20 Hz. The affection of Doppler frequency shift is lowered effectively.The modulation methods such as OFDM, frequency jumping, MFSK, time delay shift coding had been studied and simulated for comparing their shortage and advantage. According to the application to prefer the underwater telemetry signal system suitable for using to anti multipath and meet the need of telemetry.Aimed at the general design requirements of the system, the signal processing platform was constructed by using High speed float point DSP chip ADSP-TS201 as the main processor of signal processing hardware, and the serial Cyclone II FPGA as the main controller. The processing algorithms of underwater acoustic telemetry signal were programmed by using both combining the C language and assemble language.After all these works, the underwater acoustic telemetry test was conducted on lake. The test results were analyzed to validate the performances of the underwater acoustic telemetry signal and the digital signal processing system. No matters in static, dynamic or attitude sensor real time test, the error code rates both are lower than 10-3. The test results had shown that time delay shift coding + FSK in signal system can improve the performance of underwater telemetry effectively. At the same time, the effectiveness of signal processing algorithms and software designing methods are proved also.