The Study, Based On Wavelet Transform Pulsed Laser Radar Echo Signal Denoising Method

Laser radar has been extensively used both in military and civilian affairs. It is a focus in the high-tech fields at present. However in practical applications, the radar signal is inevitably influenced by various noises and interferences. Aiming to improve the detecting ability of radar, removing the noise effectively is very important. Wavelet transform is an excellent theory developing in recent years which can be used to signal processing. So the purpose of this thesis is to use wavelet transform to remove the noise of the pulse laser radar echo.The noise characteristics affecting pulse lidar system is analyzed, the model of ideal transmitting signal and the return signal are created in this paper. First, the ideal return signals are denoised using three threshold denoising method, it is concluded that the denoising method of mandatory threshold is more suitable for the selected signal by comparing the simulation results of three threshold denoising method. Subsequently, on this foundation, a new denoising approach called mandatory threshold and correlation denoising approach is proposed which is more appropriate for weak signal processing of pulse lidar system. The method of employing the mandatory threshold and correlation denoising approach after the accumulating pulse is put forwarded which is suitable for the occasions having no high real-time demand. MATLAB simulation demonstrates the method is feasible and superior. On the basis of the mandatory threshold and correlation denoising processing to be added the Automatic Gain Control system for the irregular received signals. The simulation results demonstrate that the method is effective in the restoration of signals and the improvement of SNR.