Research On Lidar Data Acquisition System And Filtering Technology Based On CPCI Bus

CPCI,as an engineering data bus, has the features of large data throughput,anti-electromagnetic interface and strong compatibility, which is widely used in the measurement and control systems. Relaying on the lidar remote sensing Research Center of Xi'an University of Technology, this dissertation firstly carried out the applied research of signal data acquisition based on CPCI bus for lidar echo: the acquisition requirements of the lidar echo signal was analyzed, and due to the engineering application, a data acquisition system based on CPCI bus was designed, the corresponding hardware was also developed; Aim at the dual-channels echo signals acquisition, a parallel acquisition architecture implementation in FPGA and a parallel acquisition control program were addressed; Based on the PLX SDK Toolkit, the underlying driver for the CPCI bus protocol was developed, the date exchange program combined the I/O mode with DMA mode was also putted forward. Finally, the addressed acquisition system can achieve the functions of data acquisition, transmission,pre-processing and other functions.The echo signal of lidar is very weak and easily interfered by strong random noise, and the wavelet transform has the unique advantages in time-frequency localization, multi-scale analysis and so on, therefore, a filtering and denoising algorithm based on wavelet transform for echo signal was carried out in this dissertation: After compared and analyzed the filtering and denoising effects of different wavelet bases and different wavelet decomposition layers, a db4 wavelet was selected, and the echo signal was decompose to 5 layers based on this wavelet base,a soft threshold function was adopted to enhance the filter; In order to fulfill the application needs, a wavelet threshold denoising algorithm based on C ++ was composed, and it was also integrated into the current data acquisition system, which can achieve the on-line filtering and denoising, finally, the SNR analysis was carried out showing that the algorithm had an positive effect.The lidar data acquisition system and the wavelet threshold denoising algorithm designed in this dissertation have been applied in the lidar atmospheric detection system, and have achieved certain results. This system will further promote the promotion and application of LIDAR technology.