卫星波束标校信号码型对比分析

针对GEO轨道通信卫星同步定点后会出现周期性漂移，导致波束指向不确定的问题，本文对波束标校系统中的信号捕获进行了研究。由于标校信号捕获依赖于标校信号之间的正交性及其自相关特性，因此文中提出了标校系统中信号码型选择需要考虑的关键问题。特别是在天线存在指向误差时，Ka频段标校站接收信号功率最大差异可达近30 dB，这给标校信号码型设计和标校信号的捕获带来了困难，因此文中从码型的抗干扰性能、实现复杂度、能量估计精度和捕获特性等几个方面，分析和对比了m序列信号、Walsh信号、单频信号和Chirp信号（扫频信号）这4种码型各自的优点和缺点，并用MATLAB进行了仿真。结果表明：在抗干扰性能上，伪随机序列信号和Walsh信号最好，Chirp信号次之，单频信号最差；在复杂度方面，Chirp最复杂，伪随机序列和Walsh序列次之，单频方式最简单；在估计精度方面，三者的估计精度相当；在捕获性能方面，Walsh信号的捕获性能明显优于m序列，而且当两个标校站的接收信号功率之间存在较大差异时，Walsh信号的捕获性能明显优于m序列。因此标校系统可优先选择Walsh码作为标校信号。

Comparative analysis of code types in satellite wave-beam calibrating system

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.