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在无源相干脉冲雷达系统中,由于直达波信号的起伏,难以实现对其脉冲重复频率实时且精确地估计,导致脉冲重复频率与采样时钟之间总是存在时间同步误差,很难满足脉冲间相参采样的条件.文中首先通过对无源相干脉冲雷达系统的中频采样过程进行建模,推导了脉冲间相对采样时刻的变化周期与时间同步误差的关系,然后定义了归一化干扰功率来分析时间同步误差对无源相干脉冲雷达系统相参处理输出的影响.在此基础上,推导了脉冲间相对采样时刻的差服从均匀分布和Gauss分布时的归一化干扰功率,并给出了相应的仿真结果.同时,推导了存在时间同步误差时Doppler频率估计的理论误差,并给出了相对采样时刻变化周期不同时Doppler频率估计的仿真实例,验证了理论分析的正确性.
In the passive coherent pulse radar system, it is difficult to estimate the pulse repetition frequency in real time and accurately because of the fluctuation of the direct wave signal. As a result, the time synchronization error always exists between the pulse repetition frequency and the sampling clock, Firstly, by modeling the IF sampling process of a passive coherent pulse radar system, the relationship between the variation period of the relative sampling time and the time synchronization error is derived, and then the normalized interference power is defined The influence of time synchronization error on the output of coherent processing in passive coherent pulse radar system is analyzed. On the basis of this, the normalized interference power when the difference of relative sampling time between pulses is derived from uniform distribution and Gauss distribution is derived. And the corresponding simulation results are obtained.At the same time, the theoretical error of Doppler frequency estimation in the presence of time synchronization error is deduced, and the simulation example of Doppler frequency estimation with different sampling period is given, which verifies the correctness of the theoretical analysis.