Abstract:Aiming at the problem of beam pointing uncertainty caused by periodic drift after GEO orbital communication satellite synchronization fixed point, the signal acquisition in beam calibration system is studied in this paper. Because the acquisition of calibration signal depends on the orthogonality and autocorrelation between calibration signals, the key problems to be considered in the selection of signal type in calibration system are proposed in this paper. Especially when the antenna has pointing error, the maximum difference of received signal power of Ka band calibration station can reach nearly 30 dB, which brings difficulties to the design of calibration signal pattern and the acquisition of calibration signal. Therefore, this paper analyzes and compares the advantages and disadvantages of m-sequence signal, Walsh signal, single frequency signal and chirp signal (sweep signal), and the simulation is made with MATLAB. The results show that in terms of anti-interference performance, pseudo-random sequence signal and Walsh signal are the best, Chirp signal is the second, and single frequency signal is the worst; in terms of complexity, Chirp is the most complex, followed by pseudo-random sequence and Walsh sequence, and single frequency mode is the simplest; in terms of estimation accuracy, the estimation accuracy of the three is the same; in terms of acquisition performance, the acquisition performance of Walsh signal is significantly better than m-sequence, and when there is a large difference between the received signal power of two calibration stations, the acquisition performance of Walsh signal is significantly better than m-sequence. Therefore, the calibration system can preferentially select Walsh code as the calibration signal.
