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Research Of Signal Detection And Data Processing For Lidar Echo

Posted on:2021-03-15Degree:MasterType:Thesis
Country:ChinaCandidate:C DuFull Text:PDF
GTID:2428330611953368Subject:Instrumentation engineering
Abstract/Summary:PDF Full Text Request
Lidar is an active remote sensing detection tool,which is widely used in atmospheric physical parameters and environmental detection.In operation,by detecting the backscattering signal of the narrow pulse laser emitted by it and interacting with atmospheric molecules and aerosol particles,the atmospheric temperature,humidity,extinction coefficient and other parameters of the detected area are obtained.In the lidar detection system,the photoelectric detection,data collection and processing of the echo signal are important links,and its performance directly aff'ects the detection performance of the lidar system.This paper focuses on the characteristics of large dynamic range,unusually weak far-field signal and large background noise of lidar echo optical signals,and carries out related research on echo signal photoelectric detection,data acquisition and data processing.The main work is as follows:For the lidar echo signal,based on two common photoelectric conversion devices photomultiplier tube(PMT)and Avalanche Photodiode(APD),the corresponding photoelectric conversion circuit and conditioning circuit are designed:according to the current output characteristics,a high-precision I/V conversion chip is selected,and the circuit parameters are optimized using Pspice to achieve fine detection of the lidar echo signal.According to the reconfigurable idea,high-gain control power supplies for PMT and APD are designed.In order to meet the needs of on-site debugging and remote control,two control modes,manual and automatic,are provided.Taking the portable,multi-channel digital oscilloscope Picoscope 4824 as the data acquisition device,and using the virtual instrument platform LabVIEW based on visualization,the lidar multi-channel data acquisition system is designed,which can realize data acquisition and storage management of multiple channels up to 20MHz.In order to eliminate the adverse effects of solar background light and detection system noise in the lidar echo signal,the signal filtering algorithm was studied.The wavelet threshold denoising method is used to process the signal,the sym7 wavelet function is used as the wavelet base,the signal is decomposed into 5 layers of wavelet,and the soft threshold function is used to filter the echo signal of the rice scattering lidar.The signal-to-noise ratio analysis shows that the algorithm has a significant denoising effect.The principles and characteristics of Collis slope method,Klett and Fernald inversion methods are analyzed.According to the actual needs,Klett meth od is selected for inversion processing.The LabVIEW inversion program is designed and integrated into the data processing system.The lidar echo signal detection and data processing research carried out in this paper can realize the lidar echo signal detection,and integrate data collection,storage management and preliminary filter inversion functions.It is portable,reconfigurable and adaptable.The characteristics can be widely used in the field of lidar detection.
Keywords/Search Tags:Lidar, photoelectric conversion, data acquisition, wavelet denoising, inversion
PDF Full Text Request
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