相干激光探测中微动参数估计的克拉美-罗界

Cramer-Rao bounds for micro-motion parameters estimation in coherent laser detection

  • 摘要: 为选择最佳参数估计方法估计目标微多普勒特征,需要研究参数估计的克拉美-罗界,来评价各估计方法的性能。以相干激光探测为背景,考虑噪声方差未知的影响,严格推导了高斯白噪声环境下微动目标回波信号各参数估计的克拉美-罗界的闭合表达式,仿真分析了目标相对于雷达的位置信息、数据处理长度以及回波信噪比与参数估计方差下界的关系。结果表明,克拉美-罗界与噪声方差无关,目标相对于雷达的方位角、俯仰角越小,数据长度和信噪比越大,参数估计的方差下界越小。对目前常用的两种微动参数估计方法方差进行了计算,并与推导克拉美-罗界进行了对比。最后,与通过近似处理方法得到的克拉美-罗界进行了对比,指出了精确推导方差下界的意义。

     

    Abstract: To choose the optimal estimating method to evaluate micro-Doppler characteristic of target,the research on the Cramer -Rao Bounds (CRBs), which was used to evaluate the performance of the estimating method, was indispensable. The closed form of CRBs for lidar signals with Gaussian noise was derived strictly in this paper. The relationships between the CRBs and factors including the target position, the length of processing data and SNR were analyzed. The simulation results indicate that decreasing the azimuth angle and pitch angle or increasing the data length and SNR can minish the CRBs of estimated parameters, while, the lower bounds are insensitive to the information of the noise variance. The mean square error of two frequently used estimators for micro -Doppler parameters were simulated and compared with the CRBs. In the end, the meaning of the strict derivation of CRBs in this paper was presented by comparing with the result got from approximate process.

     

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