Research On Signal Processing System Of Phase-Modulated Lidar

With the development of communication technology and electronic technology,lidar has been widely used in both military and civil fields because of its high measurement accuracy and space-time resolution.Lidar can more accurately detect the azimuth,distance,speed and shape of the target,and can be used to detect,identify and track the target.However,lidar also has many shortcomings.For example,its signal processing means and equipment are relatively immature,the development process is complex and the cost is high.However,RF signal processing technology has become mature,so RF signal processing technology is introduced into lidar through laser modulation technology.According to the functional requirements of phase modulated lidar for signal processing system,a signal processing system is designed and built by using the existing hardware equipment.Firstly,the concept and working principle of lidar are described.According to the limitations of lidar signal processing technology,the concept of phase modulation lidar signal processing system is introduced.The system uses the RF signal transmitted by the signal processing system to phase modulate the lidar.After filtering the laser signal,the echo signal generated by the target,The remaining RF signals are returned to the signal processing system for acquisition and processing.Then,the principle of phase modulation and the system architecture of phase modulation lidar are studied,and the design scheme of signal processing system is put forward.Secondly,the signal transmitting module of the signal processing system is designed.The FPGA chip of zynq-7000 series and ad9767 chip are selected as the structure of signal generation and digital to analog conversion,and finally the function of multifunctional signal generator is realized.Then,the signal receiving module also selects the zynq-7000 system on chip.Zynq-7000 has the characteristics of software,hardware and peripheral programmability.It can realize the logical function interconnection and function expansion between arm and FPGA by using Axi bus,and realize the high-speed signal acquisition and processing function under Linux Embedded System in combination with ad9226.The system is divided into hardware design and software design.The hardware design includes the design of each functional IP core,DMA technology is used to improve the signal acquisition rate.The software design includes the writing of Axi DMA driver and signal acquisition application program,and finally realizes the function of signal receiving module by Porting Linux operating system.Finally,according to the working principle of phase modulated lidar,the function of the phase modulated lidar signal processing system is verified by using a reasonable architecture.The process is to connect the signal transmitting module with the signal receiving module.Firstly,the multi signal digital frequency synthesizer designed by the signal transmitting module of the signal processing system based on FPGA is simulated and verified,The overall function verification of the signal processing system is realized with the signal receiving module.The results show that the real-time conversion of the frequency and amplitude of the waveform in the signal receiving module can be realized through the keys in the signal transmitting module,which verifies the basic function of the signal processing system.