Design Of Pulsed Laser Ranging System Based On FPGA

Pulsed laser ranging is widely used in the fields of security,traffic and industrial measurement because of its advantages such as simple structure,high stability and fast measurement speed.However,it has low ranging precision in the short distance measurement.In order to realize the real-time and accurate measurement and analysis of the short distance,a scheme of pulsed laser ranging system based on FPGA is proposed by combining pulsed laser ranging with FPGA.The pulsed laser ranging system based on FPGA consists of the laser emitting circuit,the laser receiving circuit,the FPGA,the power supply circuit and the host computer software.The laser emitting circuit consists of the driving circuit and the laser.The laser receiving circuit consists of the IV conversion circuit,the filter circuit,the amplifying circuit and the shaping circuit.In the design of the laser emitting circuit,in order to improve the stability of the pulse signal,the FPGA is used to generate the required pulse signals.The laser receiving circuit converts the received laser signal to the level signal which the FPGA can collect.Based on the FPGA's programmable and parallel processing characteristic,by Verilog HDL language coding,the time separation module,the "Coarse" time measurement module,the "Fine" time measurement module,the time synthesizer module,the distance calculating module are designed.The precision time interval measurement is realized.The measured time length is converted to the distance data,which is transmitted to the host computer through the data transmission module.The host computer data acquisition system is designed in Windows based on VB language,which can realize the functions of the data collection,the display,the analysis and the preservation.After the software and hardware design of the system is completed,the pulse signal required by the laser transmitting circuit is tested,and the duty cycle of the output signal is 0.000025.The performance of the laser receiving circuit is verified and tested,and the level signal can be output smoothly.The carry chain designed in FPGA is tested and the time measurement accuracy is 130 ps.A series of experiments are carried out to test the pulse laser ranging system.The experimental results show that the system can realize the function of the collection,the display,the analysis and the preservation of the measured distance data.In the measuring range of 1m to 10 m,the maximum relative error of all test points is 0.008,so the system can be better applied to the measurement of short distance.