摘要
分布式无人机载合成孔径雷达(Synthetic Aperture Radar,SAR)在实现对地海高价值目标成像感知时,具备抗干扰能力强、灵活性高、多角度观测等优势。然而,受分置各平台不同源引起的时频误差、气流扰动造成的平台站址误差等影响,分布式无人机载SAR对目标的定位精度下降。本文针对上述问题,提出了一种基于到达时间差(Time Difference of Arrival,TDOA)的分布式无人机SAR目标自定位方法。首先,通过对每个接收平台无人机接收的回波信号进行成像处理获得同一场景、不同观测方向的多帧图像,并粗略估计出目标的空间位置;其次,在考虑时频同步误差和无人机站址误差情况下,用粗略目标位置结合回波信号中的距离信息与无人机站址构建出TDOA定位方程组;随后,通过泰勒算法求解定位方程组,通过该超定定位方程组中的冗余方程对解算精度进行约束,经过解算可获得更精确的目标位置;最后,推导了在时频同步误差和无人机站址误差存在条件下的克拉美罗下界(Cramer-Rao lower bound,CRLB),对定位效果进行了评估。所提出的目标自定位方法仅利用了回波信号的距离信息,避免了回波信号的多普勒质心估计不准对定位精确的影响。仿真实验结果表明,该定位方法可在时频同步误差和无人机站址误差存在条件下实现对目标的精确定位。
Unmanned aerial vehicle(UAV)airborne multistatic synthetic aperture radar(SAR)has the advantages of strong anti-interference ability,high flexibility,and multi-angle observation regarding imaging perception of high-value targets on the ground and at sea.However,the localization accuracy of the UAV airborne multistatic SAR on targets tends to be seriously affected owing to time-frequency errors caused by the separation of SAR transmitters and receivers,UAV position errors caused by airflow disturbances,and other factors.To address the aforementioned problems,this paper proposes a self-localization method for UAV airborne multistatic SAR based on time difference of arrival(TDOA).First,multiple images of the same scene from different perspectives were obtained by performing back projec‐tion(BP)imaging on the received signals,and the target position was approximated.Subsequently,considering time frequency synchronization and UAV position errors,the TDOA localization equations were constructed using the rough target position,range information of received signals,and the UAV positions.A more accurate target position was then estimated by using the Taylor algorithm to solve the localization equations,because the solution accuracy was con‐strained by the redundant equations in the overdetermined localization equations.Finally,the Cramer Rao lower bound(CRLB)was derived to evaluate the proposed method under the above errors.Since the proposed self-localization method utilizes only the range information of the received signals,it avoids the adverse impact of inaccurate Doppler centroid estimation of the received signals on positioning accuracy.Numerical simulations validate the effectiveness of the method under time-frequency synchronization and UAV position errors.
作者
杨佳鑫
毛馨玉
王朝栋
李中余
武俊杰
杨建宇
YANG Jiaxin;MAO Xinyu;WANG Chaodong;LI Zhongyu;WU Junjie;YANG Jianyu(School of Information and Communication Engineering,University of Electronic Science and Technology of China,Chengdu,Sichuan 611731,China)
出处
《信号处理》
CSCD
北大核心
2024年第9期1587-1596,共10页
Journal of Signal Processing
基金
国家自然科学基金(62171084)。
关键词
分布式合成孔径雷达
无人机
目标定位
到达时间差
multistatic SAR
unmanned aerial vehicle
localization
time difference of arrival
