基于斜距多普勒分析的雷达前视测高方法

针对基于正下视天线几何构型的传统雷达高度计不适用于天线前向安装的弹载雷达导引头系统的问题，提出一种基于回波斜距多普勒分析的适用于前下视几何构型的雷达测高方法。该方法利用平台与目标间相对高度、速度、斜距及多普勒之间的几何关系实现高度测量，并采用方位谱相关法实现由前视几何引起的非均匀方位谱分布条件下的多普勒中心估计。首先对回波进行距离匹配滤波和方位去斜处理，实现距离方位二维聚焦。然后在距离向进行子段划分处理提高测高精度及稳定性。在每一距离子段中，通过波门和采样点推算斜距，采用方位谱相关法估计多普勒中心，并根据测高几何关系估计高度值。最后对各子段测高值进行能量筛选和平均后输出最终测高结果。仿真和实测数据处理结果均表明本文所提方法应用于弹载雷达导引头前视测高有很好的测高精度。

Altitude Estimation for Forward-Looking Radar Based on Range-Doppler Analysis

This paper proposes a new radar altitude estimation method appropriate for front-looking illumination based on range-Doppler analysis, to solve the problem that the conventional radar altimeter with down-looking antenna is not appropriate for the missile-borne radar seeker with forward-looking antenna. The altitude estimation method utilizes the geometrical relationship among the relative altitude, velocity, range and Doppler center between the seeker and the illuminated region. And a Doppler central frequency estimation method based on spectral energy correlation is applied for the case of non-uniform azimuth spectrum caused by front-looking geometry. Firstly, range matching filtering and azimuth de-chirping are performed to achieve two-dimensional focusing. Then, range segment is carried out to enhance the estimation accuracy and stability. For each segment, the range is acquired from the range gate and the sampling point, the Doppler central frequency is estimated by spectral energy correlation method, and the altitude is calculated by the estimated Doppler central frequency and the corresponding range bin according to the geometrical relationship. Finally, the altitude values within the main-lobe width of the antenna beam are selected and averaged to obtain the final altitude. Simulation and experimental results show that this method has high estimation accuracy for forward-looking missile-borne radar seeker.