Research On Photon Counting Lidar Ranging System Based On Pseudo Random Code Modulation

Lidar ranging technology has the characteristics of high precision and good reliability.It is widely used in the fields of interplanetary terrain mapping,underwater target detection and weak signal detection.In view of the low signal-to-noise ratio of traditional ranging methods,this paper designs a pseudo-random code modulated single photon lidar ranging system based on high-performance FPGA by using photon counting method to achieve accurate ranging of target objects:(1)This paper analyzes the principle and characteristics of common lidar ranging methods,puts forward the ranging method of pseudo-random code modulated laser,studies the overall structure of single photon lidar,analyzes the functions of lidar transmitting system,receiving system and main control system,and designs the ranging system scheme of pseudo-random code modulated single photon lidar.(2)According to the design scheme of the single photon lidar ranging system,the driving circuit of the transmitting system is designed to ensure the stable operation of the laser;the LVDS signal conversion circuit is designed to convert the FPGA output signal into the signal required by the laser modulator;according to the working principle of the single photon receiver,the hardware circuit is built for the receiving system to ensure the stability of the InGaAs SPAD single photon detector is in a stable working state to improve the receiving rate and signal-tonoise ratio.(3)According to the requirements of system function design,the software system of single photon lidar is written: the pseudo-random code sending module is designed to generate the set order pseudo-random code sequence and modulate the laser emission;the circuit control program is designed;the data processing module is designed to complete photon counting and correlation operation,get the time information and calculate the target distance.A complete experimental system with 1550 nm wavelength semiconductor laser as the system light source and InGaAs SPAD as the single photon receiver is constructed for experimental verification.The experimental results show that the system designed in this paper can meet the task requirements in detection distance and detection accuracy.