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利用卫星导航系统对高轨航天器进行自主导航与高精度定轨,对接收机的捕获灵敏度要求极高,双块补零(DBZP)算法是无辅助下卫星导航弱信号捕获的理想方案,然而受限于数据处理量大,DBZP实际应用难度大。在深入分析双块补零机理的基础上,结合矩阵重构的思想,提出了一种改进双块补零北斗导航接收机弱信号捕获方法。该方法对参与块内相关运算的基带信号和本地测距码分别进行重构,解决了块内点数与快速傅里叶变换输入点数之间的矛盾,提高了北斗导航接收机弱信号捕获性能。仿真实验结果分析表明,改进双块补零算法对信噪比没有损失,可以保证对低至15dB·Hz的弱信号进行有效捕获,能够满足高轨航天器定轨、室内外无缝导航等对接收机高灵敏度的需求。本方法是在块内运算层面对DBZP进行优化,具备良好的通用性和可移植性,与优化相干积分策略的各种改进DBZP算法可以无缝对接,进一步提高北斗导航接收机信号处理的效能。同时,重构的思想也适用于其他采用码分多址信号的卫星导航系统的弱信号检测和捕获,对提升多星座卫星导航系统的基带信号处理性能具有参考意义。
Autonomous navigation and high-precision orbit determination of high-altitude orbit spacecraft using satellite navigation systems require extremely high acquisition sensitivity of the receiver. The double-block zero-padding (DBZP) algorithm is an ideal solution for acquiring weak signals of satellite navigation without assistance. However, Limited by the large amount of data processing, DBZP practical difficult. On the basis of deeply analyzing the double-patch zero-padding mechanism and combining the idea of matrix reconfiguration, a weak signal acquisition method is proposed to improve the double-patch pad-zero Beidou navigation receiver. The method reconstructs the baseband signal and the local ranging code which are involved in the correlation operation in the block respectively, resolves the contradiction between the points in the block and the input points of the fast Fourier transform, and improves the acquisition performance of the weak signal of Beidou navigation receiver. The simulation results show that the improved two-piece zero-padding algorithm has no loss of signal-to-noise ratio and can effectively capture the weak signals down to 15dB · Hz, which can meet the requirements of orbit and indoor and outdoor seamless navigation Receiver high sensitivity needs. The method optimizes the DBZP in the intra-block computing layer and has good versatility and portability. The improved DBZP algorithm can be seamlessly connected with the optimized coherent integration strategy to further improve the signal processing performance of Beidou navigation receiver. At the same time, the idea of reconstruction is also applicable to the detection and acquisition of weak signals in other satellite navigation systems using code division multiple access signals, which is of reference significance to improve the baseband signal processing performance of the multi-constellation satellite navigation system.