Signal Processing System Design And Implementation Of Multi-beam Terrain Detection

As an essential data of marine exploitation, the seafloor terrain and relief have an important role in ensuring the safety of shipping industry, marine construction project, which are emphasized around the world. The multi-beam sounding system is a wide coverage, high efficiency and precision underwater terrain survey equipment, and has become a mainstream instrument of seafloor terrain detection. So studying the key technology of multi-beam sounding system has a very important social economy significance.There are various errors and environmental interference in the process of sounding data collection, and these disturbances will affect the quality of the depth data, so a reasonable method is needed to eliminate various errors, which was carried out by optimizing them through hardware and software to get accurate measurement results. Study the method of the seafloor sounding data trend surface filtering on software, and the system can detect and eliminate gross errors more objective, compared with the median filtering technology. We preprocess the sound velocity profile by refraction correction method, calculate the seafloor terrain sampling data again, and improve the accuracy of sounding system coordinated by judging and fitting the error of location data. We interpolate and smooth the data after eliminating the gross error, merge and process the data, and then get the information of(x, y, z) on geodetic coordinates. Design the function of automatic gain control on hardware in the data receiving module to ensure the output signal of receiving module can maintain steady levels. The data processing module uses MC74LCX16245 buffer chip to control the process of analog to digital conversion data, and the chip reduces the size of the circuit board, improves the speed of data processing effectively. The digital beam forming module uses TMS320C6713 DSP chip to achieve high efficiency and meets the requirement of system performance.DSP software development verifies the correctness of beam-forming algorithm. The system performance testing and data acquisition experiments validate the feasibility of the hardware circuit and the correctness of the algorithm. The software,which is designed to eliminate, interpolate and smooth the outlier of raw data, is suitable for the preparation of multi-beam bathymetric data processing, so it can eliminate the gross error and random error, and compensate the system error caused by location and attitude data. Eventually we merge location and depth data, and converse them to geodetic coordinates, to generate highly accurate three-dimensional seafloor sampling data, which makes establishment for the digital geographic foundation in the future.