Doppler Laser Radar For Range And Speed Measurement

Precise measurement of road target range and speed is a core technology for realizing automobile intelligent driving,which has already been achieved by using microwave radar and obtained wide application.However,space resolution of microwave radar is poor due to the large beam width,which causes classification of the targets difficult.By lens collimation,Gaussian transverse mode of semiconductor laser can be transformed to a divergence angle of less than 1mrad.Thus,by developing lidar which has superior space resolution,it is possible to improve the performance of target recognition and the safety of intelligent driving car.Nowadays laser radars on sale measure target range,but cannot measure target speed simultaneously.Target speed is obtained by measuring target range twice and calculating range variation.The speed obtained in this way has drawbacks of large error and time consuming,and cannot meet the requirement of intelligent driving.So,it is necessary to develop a lidar that has the same performance on range and speed measurement as the microwave radar.In this paper,we proposed a method of inserting periodic codes into pseudo random noise codes for constructing modulation codes.At transmitting end,amplitude of transmission signal is modulated by the modulation codes,while at the receiving end,calculating correlation function of received laser radar echo signals for measuring target range and sampling beat signal from periodic pulse time slot for analyzing frequency of beat signal,thus target speed.By the method,we realized a transmission signal length less than 1?s,range measurement error less than 10 cm,speed measurement error less than 1m/s.The transmission signal length meets the requirement of high scanning.