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合成孔径激光雷达(SAL)的激光光源啁啾非线性会严重恶化距离向分辨率,无法清晰成像。针对这一问题,建立了存在非线性啁啾误差的SAL回波信号模型,分析认为非线性啁啾误差影响成像的本质为成对回波效应,并提出一种校正光源啁啾非线性的改进频率变标算法。该方法应用傅里叶变换时移特性估计非线性大小,基于剩余视频相位滤波原理“三步法”完成非线性啁啾的校正处理,实现目标的精确成像。仿真实验表明分辨率和成像质量获得明显改善,从而验证了该算法的可行性和高效性。
Chirped non-linearity of the laser source of synthetic aperture laser radar (SAL) can seriously deteriorate the range resolution and can not be clearly imaged. In order to solve this problem, a SAL echo signal model with nonlinear chirp error is established. It is considered that the nonlinear chirp error affects the imaging’s essence as the paired echoes and proposes an improvement of nonlinearity of the chirped light source Frequency scaling algorithm. The method applies the time-varying characteristics of the Fourier transform to estimate the nonlinear magnitude, and completes the nonlinear chirp correction processing based on the residual video phase filtering principle and the “three-step method” to achieve the accurate imaging of the target. Simulation results show that the resolution and image quality are significantly improved, which verifies the feasibility and efficiency of the proposed algorithm.