时变时/频差对长时相关积累的影响分析及补偿策略

Effect of Time-Varying TDOA/FDOA on Long-Time Coherent Integration and Compensating Strategy

针对同步双星定位系统中时/频差(TDOA)/(FDOA)时变引起长时相关积累增益损耗的问题,将上下行传播链路的相对运动均考虑在内,推导同步双星系统中时变时/频差条件下的信号模型;在此基础上,根据规则信号自相关函数与能谱密度之间的关系以及线性调频信号的频谱特性,分别定量分析时变时/频差对长时积累时/频差维相关峰值幅度损耗的影响;给出了时变时/频差补偿策略和实现步骤。实际数据处理结果表明,本文给出的补偿策略能够实现长时相关积累的能量聚焦,时变引起幅度损耗定量分析结论的有效性也得到验证。

In a dual-GEO-satellite passive location system, the time-varying time difference of arrival （TDOA）/ frequency difference of arrival （FDOA） may induce the gain loss of the long-time coherent integration. Aiming at this problem, the received signal model with time-varying TDOA/FDOA is derived including both uplink and downlink relative motion. Then, according to the relationship between the regular signal＇ s autocorrelation function and energy spectrum density, the correlation peak magnitude loss in TDOA dimension is analyzed quantitatively; according to the frequency spectrum characteristics of the linear frequency modulation signal, the loss in FDOA dimension is analyzed quantitatively. Also, the compensating strategy and implementation procedure are provided. The validity of the compensation strategy and quantitative analysis is verified by processing the actual signal.