The System Design And Signal Denoising Of Backscattering Visibility Lidar

Visibility reflects optical state of the atmosphere. It plays an important role in both transportation and military defense. Because of short wavelength, high sensitivity, and high resolution, laser radar has become a new tool to observe the atmosphere visibilityA small type of laser radar base on the principles of atmospheric backscatter has been developed in this paper, and the radar has advantages of compact structure, safety in use,small and convenient. What is more, this paper discussed the choices of important device and parameters of the device in detail, analysed SNR estimated method and the noise characteristic of radar echo signal.Because of the influence of the noise, useful signal in laser radar echo signal is so weak that the detecting range and precision are affected. There for, a detailed research of echo signal preprocessing was done in this paper. Morphology filter and EMD were used to denoise because the echo signal is a kind of nonlinear signal. First of all, the principle of two algorithms were described in detail, then we summarized characteristics of algorithms according to simulation experiment and results, done the real echo signal denoising experiments. Finally, a distortion problem appeared when we used EMD for denoising, and we analyzed the causes and proposed a combinational algorithm called morphology-EMD.The denoising results proved that this combinational algorithm can reduce the former distortion problem effectively according to the comparison of the experiment results.