Mie散射激光雷达回波信号处理方法

Return signals processing method of Mie scattering lidar

为了提高Mie散射激光雷达测量斜程能见度的精度,提出了一种回波信号处理的组合算法。首先,采用基于经验模式分解(EMD)的自适应算法,去除回波信号中的高频噪声,提高信噪比。其次,采用基于不动点原理的迭代算法进行消光系数的反演,它不需要准确的边界值就可计算消光系数均值,同时还能得到准确的边界值,可用于求取消光系数的分布。数值仿真表明:EMD算法比五点三次平滑去噪算法输出信噪比提高4.67 dB,不动点迭代算法比最小二乘法估算消光系数边界值算法反演得到的消光系数均值的相对误差减小31.50%,而迭代次数只有3～5次,因此该组合算法是有效的。

To improve the slant visibility measuring accuracy of Mie scattering lidar,a combination algorithm for return signals processing was proposed.Firstly,the adaptive algorithm based on empirical mode decomposition（EMD） was applied to improve the SNR of return signals by removing the high frequency noise.Secondly,the iteration algorithm based on fixed point principle was used to invert extinction coefficient.Using this algorithm,the mean extinction coefficient could be calculated without the accuracy boundary value.Additionally,the accurate boundary value was obtained,via which the extinction coefficient distributing could be achieved.Numerical simulations show that the output SNR of EMD algorithm increases 4.67 dB compared with five point three times smoothing denoising algorithm;the relative error of mean extinction coefficient inverted by fixed point iteration algorithm is 31.50% smaller than the value obtained by the least square fitting algorithm for the estimation of the extinction coefficient boundary value.Furthermore,only 3 to 5 iterations are required.Therefore,the combination algorithm is effective.