A Study On The Several Key Technologies For The Low-Cost SOTM System

Based on the developed actuality of the satellite communication on the movesystem (SOTM), this paper studies the key techniques in the vehicular mobile satellitecommunication system with the characteristics of small size and low cost. Somealgorithms of the system are improved and the validity of the improved algorithms isproved by the simulation. The circuit of the servo control modular is designed bySystem-On-Chip.To solve the problem of tracking speed in step tracking algorithm, a step trackingalgorithm based on the steepest descent method is proposed. This algorithm adjusts thetracking direction and step size by the steepest descent method. The simulation resultsshow that the numbers of tracking are reduced to17steps. To tackle the problem ofgeographic north need to be determined in initial alignment, when the antenna pointingis controlled to tracking the target satellite in the azimuth plane, a tracking algorithmbased on TOP method is proposed. This algorithm is used in the initial alignment, itdoes not need to determine geographic north in azimuth plane. The simulation resultsshow that the antenna pointing can aim at the target satellite quickly and this algorithmcan reduce complexity of the system. For filtering the noise in MEMS gyroscope whichwill cause antenna pointing angle exist the errors and then the errors make the antennapointing deviate from the target satellite, a method based on the morphology is proposed.The simulation demonstrates that the algorithm is effective in signal extracting andde-noising. In the study of servo control module, the morphology is used in error signalprocessing. The simulation results show that the method can depress the overshoot andimprove the response and steady state performance.