Return signals processing method of Mie scattering lidar

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.