DS/FH扩频测控信号同步方案的捕获性能

Acquisition Performance of a Synchronization Scheme of DS/FH Spread Spectrum TTC Signals

针对航天测控信号的高动态以及由载频跳变引起的多普勒频率周期跳变的特点,提出了一种基于快速频率识别和辅助机制的直扩/跳频(DS/FH)混合扩频测控信号的一种同步方案。建立了跳频图案,伪码相位及多普勒频率的三维同步捕获状态转移过程的数学模型,推导出三维捕获的平均捕获时间表达式,及在伪码相位误差、多普勒频移和高斯白噪声条件下的检测概率和虚警概率表达式。仿真分析了在采用时域匹配滤波、频域多通道的直扩捕获方式下,信号和捕获系统参数对三维捕获性能的影响。理论推导与数值仿真结果表明了同步方案的有效性,并为信号设计及捕获系统参数选择提供了理论依据和实际参考。

For the high dynamic characteristics of TTC signals and doppler shift periodic hopping caused by carrier frequency hopping,a synchronization scheme of DS/FH spread spectrum signals based on a fast frequency identification method and aiding mechanism is proposed.The state transition mode of three-dimensional synchronization process in frequency hopping pattern,PN code phase and Doppler shift is given,and the expressions of the mean acquisition time and both detection probabilty and false alarming probability of an acquisition system are derived in the presence of PN code phase error,Doppler shift and Gaussian white noises.The impact of the signal and the acquisition system parameters on the acquisition performance is analyzed by numerical simulation in the case of the acquisition mode of matched filter in time domain and multiple channels in frequency domain.Results of theoretical derivation and simulation provide theoretical basis and practical reference for signal design and parameters selection of the acquisition system.