无源双基地脉冲雷达频率同步误差影响分析

Impact of Frequency Synchronization Error on Passive Bistatic Pulse Radar

在无源双基地脉冲雷达系统中,由于直达波信号的起伏,非合作接收系统难以对雷达辐射源的频率进行精确估计,因而导致接收与发射平台间总是存在频率同步误差。针对中频正交处理器的幅相不平衡度是频率的函数,文章首先给出了存在一定频率同步误差时接收系统输出的频谱和功率损耗,定性指出了频率同步误差对无源双基地雷达动目标检测的影响,然后为定量分析系统相参处理后输出的多个干扰频率分量的影响,定义了归一化干扰功率并推导了其与幅相不平衡度间的解析表达式,同时给出了多种信杂比条件下的量化分析结果。研究结果表明,无源双基地脉冲雷达相参处理输出的多个干扰频率分量将导致目标通道输出的信杂比急剧减小,严重影响目标信号的检测和参数估计。

In passive bistatic coherent radar system,the receiver needs to independently solve the problem of frequency synchronizations via the fluctuating direct-path signal.Under the circumstances,however,it is difficult to achieve highly accurate frequency synchronization since the instantaneous frequency measurement accuracy depends on the signal to noise ratio of the direct-path signal.In this paper,we focused on the impact of frequency synchronization error（FSE） on passive bistatic pulse radar system which adopted double-channel.Since the imbalance between the in-phase（I） and quadrature（Q） channel is a function of frequency,the imperfection arises from FSE in digital I and Q components has been introduced.The power loss is calculated with respect to amplitude and phase imbalance factors.An analysis that explains how the extraneous components generated is presented.Then normalized interference power（NIP） is defined to evaluate the impact of FSE in quantity.Simulation results of different signal to clutter ratio demonstrated the validly of the theory analysis.