Font Size: a A A

Research On The Visibility Detection And The Denoising Method Of The Echo Signal Based On Lidar

Posted on:2019-10-24Degree:MasterType:Thesis
Country:ChinaCandidate:L Y ZhuFull Text:PDF
GTID:2428330545470117Subject:Electronics and Communications Engineering
Abstract/Summary:PDF Full Text Request
To solve some problems with the current lidar visibility meter,such as the large size,the high cost and the complicated operation,a lidar visibility detection system based on the principle of Mie scattering and the coaxial design has been developed in this paper.However,the actually obtained lidar echo signal is extremely weak,coupled with the influence of various types of noise,reducing the effective detection distance and measurenent accuracy of the system.Therefore,a denoising method based on the empirical mode decomposition(EMD)is proposed for extracting weak echo signals effectively in this paper.The specific contents are concluded as follows:1.Based on the theory of lidar atmospheric detection,taking into account factors such as the safety,cost,and overall performance of the system,we employ the novel photonic devices and techniques such as coaxial transceiver and multi-core optical fibers,etc.The cost of the lidar visibility detection system is reduced effectively,and the system structure is more compressed.In addition,the photon counting is used to collect the echo signal,which effectively improves the detection capability of the system.2.Based on the characteristics of the lidar echo signal,we propose an EMD-based method(EMD-STRP)for the signal denoising.By analyzing the correlation between the intrinsic mode function and the echo signal,the relevant and irrelevant modes can be determined.On this basis,the roughness penalty and the soft thresholding techniques are,respectively,applied to the irrelevant and relevant modes to effectively extract the useful signal from the strong background noise.In the simulation experiment,compared with the denoising effects of EMD partial reconstruction,EMD hard thresholding and wavelet transform,EMD-STRP achieved the highest output signal to noise ratio and the lowest root mean square error.3.In order to verify the effectiveness of EMD-STRP in the lidar signal processing,this method was applied to the measured echo signal.The experimental results showed that the signal to noise ratio of the denoised echo signal was improved from 35.41dB to 38.53dB,and the effective detection distance of increased from 7km to 8.5km.The accuracy of the results was verified by the sun photometer.At the same time,comparing the visibility detection results of the system with the real data,the rationality of the lidar visibility measurement system and the denoising method was verified.
Keywords/Search Tags:Visibility, Lidar, Denoising, Empirical mode decomposition
PDF Full Text Request
Related items