Study On Receiving Circuit Design And System Optimization For Dual Frequency Pulse LiDAR

As a new detection technology in the 21st century,LiDAR has been used in commercial,military,and civilian fields.With the acceleration of technological iterations,depth-sounding LiDAR has shown advantages in many aspects.According to the popularization of market applications,its high cost will gradually come down,and more applications will be found in wind power,civil aviation,meteorology,and other fields in the future.The echo signal received by the receiving system contains important information such as laser flight time,laser energy,etc.However,in outdoor experiments,the laser energy is interfered by atmospheric attenuation,target surface reflection,and backscattering of underwater impurities,which affects system performance.And when adjusting the p?mp energy of the laser host computer control panel,it usually takes a long time for the laser to stabilize.And the selection of the photodetector will also deeply affect the measurement accuracy.The research task of this paper is to design a low-noise and experimentally flexible receiving circuit,which can ensure the detection depth and control the measurement accuracy.The paper briefly reviews the ocean detection technology of LiDAR at home and abroad.Because the LiDAR technology used for land measurement is relatively mature,it mainly s?mmarizes some of the problems that LiDAR still exists in ocean detection,and the technology is relative to sonar.And other advantages of traditional oceanographic surveying technology.Then,it is divided into the initial stage,the development stage,and the practical test stage to introduce the technical level of each stage,as well as some relatively representative LiDAR systems produced by various countries.This article first describes the composition of the lidar system,and then introduces the principle of the pulse lidar receiving circuit,including:the basic composition of the receiving circuit,the relevant knowledge of the photodetector,and the selection of the amplifying circuit.In response to the requirements of this project for echo signal detection technology,the following circuit design is proposed in Chapter 3:? APD high-voltage drive circuit design;? Transimpedance amplifier circuit design;? RF amplifier circuit design;?Positive and negative dual-channel DC stabilized power supply Design;? Design of secondary amplifier circuit.In order to verify the measurement accuracy of the designed circuit,experimental testing and result analysis of the overall receiving circuit are done.In response to some of the problems encountered in the experiment,two system optimization methods are proposed.?A method of remotely adjusting the PMT gain is proposed,which can reduce the error caused by manual operation during the experiment;?A method for laser emission energy is designed.The measurement method can take into account the measurement of large and small laser energy,and is not limited by the energy measurement range.The lidar receiving system designed in this paper uses the dual-channel detection of APD and PMT,which can distinguish the echo signals from the water surface and the bottom.At the same time,both adopt high-bandwidth circuit design,which is enough to restore the authenticity and accuracy of the echo signal.After testing,it can respond to ns-level laser signals,with a minimum detectable echo signal of 10 nW,the bandwidth of the transimpedance amplifier circuit is above 200 MHz,and the gain of the secondary amplifier circuit is within 40 dB.The design of the receiving circuit has certain reference value for the detection technology of lidar.