Design Of Multi-wavelength LED Light Source Radar Signal Acquisition System

In order to realize the space-time detection of near-surface and multi-wavelength aerosols,and overcome the problem of insufficient selectivity of laser wavelength,a novel light-emitting diode(LED)source radar is designed by using the rich spectral characteristics of LED.Since the system is a white LED source radar,it needs to be split to obtain echo signals of different wavelengths.In order to collect echo signals of different wavelengths as the data base of atmospheric aerosol inversion,the following multi-channel high-speed radar echo data acquisition system is designed.The work of this paper mainly includes the follo.wing aspects:Firstly,this thesis proposes a white LED light source radar aerosol detection system scheme,introduces the system structure and working principle,and elaborates on the two radar splitting schemes and their working principles.Based on the analysis of the white LED spectrum,fo ur detection wavelengths were determined.This proj ect identifies a radar splitting scheme using a combination of dichroic mirrors and filters,and discusses the radar equations and three solving methods under different conditions.Firstly,the composition and working principle of the white LED light source radar system are expounded,and the characteristics of the radar echo signal are analyzed.Then,according to the relevant characteristics of the radar echo signal,the parameter requirements of the data acquisition system are determined,and based on this,A multi-channel synchronous radar echo signal data acquisition system based on FPGA and Gigabit Ethernet is proposed,and the data inversion algorihms of three radar echo signals under different conditions are compared.Then carry out hardware selection and circuit design of each module of the system,including FPGA core board circuit,four-way A/D acquisition circuit,trigger circuit,Ethernet transmission circuit and so on.Then,the schematic design of the module hardware,the overall layout anddrawing of the PCB are carried out,and finally the welding and debugging of the data acquisition circuit board is completed.Secondly,the software design of the radar echo data acquisition system is completed.The design and simulation of the lower computer program of the data acquisition system are carried out on the Quartus ? development platform,in,cluding four A/D acquisition modules,asynchronous FIFO data buffer module and Ethernet data transmission.Software design for modules and A/D acquisition clock modules.And use LabVIEW to design the upper part of the system program,including the cumulative average,storage and display of radar echo data.Finally,the designed data acquisition system is applied to the multi-wavelength LED light source radar system in the laboratory.The correctness of the multi-channel synchronous data acquisition system designed in this paper is verified by system measurement,and the collected four-channel radar echo data is smoothed.Filtering,distance square correction and inversion calculations.