合成孔径激光雷达非线性啁啾克服的匹配滤波算法

Algorithm of Matched Filtering Overcoming Nonlinear Chirp Effect in Synthetic Aperture Ladar

合成孔径激光成像雷达发射的信号一般为线性啁啾激光信号,然而激光器的实际扫频特性会产生二次及高次等非线性项。非线性项的存在会造成相位误差,导致距离向成像聚焦模糊,降低距离向成像分辨率,因此必须对光源的非线性啁啾进行补偿。因此提出非匹配参考通道匹配滤波算法对非线性啁啾相位误差进行克服。仿真结果显示,距离向图像可以得到较好压缩。同时,还分析了参考通道长度及非线性贡献比例等不同参数环境下的距离向压缩效果。

Linear chirp laser signal is often employed as the transmitted signal of synthetic aperture laser （SAL） radar. However, actual frequency sweep properties of fiber laser always produces nonlinear terms such as quadratic and higher order terms. Existence of nonlinear terms produces phase errors during pulse time, leading to blurring of target in range direction and further reduces imaging resolution of range direction. It makes compensation of the nonlinear chirp from laser source. An algorithm of matched filtering in frequency spectrum to overcome the phase error from nonlinear chirp is developed. The results of simulation show that the image in range direction can be well compressed. At the same time, effects of signal compression in the range direction under different parameter situations, such＇as reference channel length as well as ratio of nonlinear contribution, are analyzed.