Design Of Small Array Lidar Signal Acquisition Circuit

Lidar is a combination of laser technology,optoelectronic technology and information processing technology.Lidar uses laser to detect and measure.Compared with passive electro-optic sensor or microwave radar,laser radar has high resolution,high working frequency,good concealment,small size,light weight,high reliability and anti-active interference,which makes it more competitive.Lidar can collect and process large amounts of data quickly,in real time,and is one of the most important remote sensing technologies.It can be used for various distance measurements,azimuth detection,altitude measurement and three-dimensional imaging.It is widely used in the military field,civilian field,space and ground.Basically,lidar consists of a transmitting system,a receiving system,and a signal processing system.This paper focuses on the research and design of a parallel processing system for lidar signals that can receive multiple echo signals.According to the principle of ranging distance imaging by lidar,based on the time-of-flight distance measurement technology,the hardware architecture of laser echo signal processing is constructed,including laser echo signal detection system,weak signal detection system,timing system and distance image display system.Avalanche photodiode arrays are used as photodetectors to convert laser echo signals into electrical signals.Since the converted electrical signal is very weak,the laser echo signal is amplified by using a weak signal detection technique such as a transimpedance amplifier and a voltage amplifier.Using frontier time discrimination method,the arrival time of the echo signal is determined by the voltage comparator,so as to prepare for the subsequent timing circuit to receive the signal.Using FPGA to time,control laser emission,transfer data to the host computer and other functions.The timing module uses digital technology implemented by a high-speed parallel counter to accurately record the time interval between the emitted laser pulse and the laser echo pulse,providing data for distance measurement and distance imaging.The FPGA transmits data to the host computer through the USB interface,and the distance image of the pulsed lidar can be realized through software developed in the host computer.The lidar signal processing system has been verified by simulation that the 64-channel laser echo signal can be processed in parallel.The maximum distance is 3km and the ranging accuracy is 2ns.The distance imaging of the laser radar can be realized.The system uses universal elements,which makes it have the advantage of scalability.