Uniform linear array(ULA)radars are widely used in the collision-avoidance radar systems of small unmanned aerial vehicles(UAVs).In practice,a ULA's multi-target direction of arrival(DOA)estimation performance suf...Uniform linear array(ULA)radars are widely used in the collision-avoidance radar systems of small unmanned aerial vehicles(UAVs).In practice,a ULA's multi-target direction of arrival(DOA)estimation performance suffers from significant performance degradation owing to the limited number of physical elements.To improve the underdetermined DOA estimation performance of a ULA radar mounted on a small UAV platform,we propose a nonuniform linear motion sampling underdetermined DOA estimation method.Using the motion of the UAV platform,the echo signal is sampled at different positions.Then,according to the concept of difference co-array,a virtual ULA with multiple array elements and a large aperture is synthesized to increase the degrees of freedom(DOFs).Through position analysis of the original and motion arrays,we propose a nonuniform linear motion sampling method based on ULA for determining the optimal DOFs.Under the condition of no increase in the aperture of the physical array,the proposed method obtains a high DOF with fewer sampling runs and greatly improves the underdetermined DOA estimation performance of ULA.The results of numerical simulations conducted herein verify the superior performance of the proposed method.展开更多
传统频率步进(Stepped frequency,SF)测量体制通过一组等间隔的离散点频信号合成大测量带宽。由于采样定理的限制,固定频率间隔数据所对应的时域信号将会呈周期出现,此时场地内的背景、多径干扰都有可能混叠至目标区域内,进而对成像和...传统频率步进(Stepped frequency,SF)测量体制通过一组等间隔的离散点频信号合成大测量带宽。由于采样定理的限制,固定频率间隔数据所对应的时域信号将会呈周期出现,此时场地内的背景、多径干扰都有可能混叠至目标区域内,进而对成像和散射测量造成恶劣影响。围绕频率步进体制快速测量方法进行了探索,提出了一种基于非均匀采样的近场散射测量技术。分析了距离混叠效应对散射测量的影响,根据实际应用需求设计了采样函数的优化原则,通过泊松和公式与驻定相位原理(Principle of stationary phase,POSP)对信号包络进行赋形。针对传统非均匀采样重构方法所造成的散射图像退化问题,提出了一种与非均匀采样策略相适配的加权方法,在有效抑制混叠干扰的同时实现了高分辨率成像,并提升了近远场变换(Near Field to Far Field,NF-FF)的精度。展开更多
基金National Natural Science Foundation of China(61973037)National 173 Program Project(2019-JCJQ-ZD-324)。
文摘Uniform linear array(ULA)radars are widely used in the collision-avoidance radar systems of small unmanned aerial vehicles(UAVs).In practice,a ULA's multi-target direction of arrival(DOA)estimation performance suffers from significant performance degradation owing to the limited number of physical elements.To improve the underdetermined DOA estimation performance of a ULA radar mounted on a small UAV platform,we propose a nonuniform linear motion sampling underdetermined DOA estimation method.Using the motion of the UAV platform,the echo signal is sampled at different positions.Then,according to the concept of difference co-array,a virtual ULA with multiple array elements and a large aperture is synthesized to increase the degrees of freedom(DOFs).Through position analysis of the original and motion arrays,we propose a nonuniform linear motion sampling method based on ULA for determining the optimal DOFs.Under the condition of no increase in the aperture of the physical array,the proposed method obtains a high DOF with fewer sampling runs and greatly improves the underdetermined DOA estimation performance of ULA.The results of numerical simulations conducted herein verify the superior performance of the proposed method.
文摘传统频率步进(Stepped frequency,SF)测量体制通过一组等间隔的离散点频信号合成大测量带宽。由于采样定理的限制,固定频率间隔数据所对应的时域信号将会呈周期出现,此时场地内的背景、多径干扰都有可能混叠至目标区域内,进而对成像和散射测量造成恶劣影响。围绕频率步进体制快速测量方法进行了探索,提出了一种基于非均匀采样的近场散射测量技术。分析了距离混叠效应对散射测量的影响,根据实际应用需求设计了采样函数的优化原则,通过泊松和公式与驻定相位原理(Principle of stationary phase,POSP)对信号包络进行赋形。针对传统非均匀采样重构方法所造成的散射图像退化问题,提出了一种与非均匀采样策略相适配的加权方法,在有效抑制混叠干扰的同时实现了高分辨率成像,并提升了近远场变换(Near Field to Far Field,NF-FF)的精度。
