Design Of Multi-channel Time Acquisition System For Shooting Range Based On FPGA

In the production,shaping,and testing of all kinds of shooting weapons,the speed of projectile flight is an important indicator to measure the characteristics of guns,ammunition and ballistic,which needs to be measured with high accuracy.At present,the regional intercept speed method is widely used in shooting ranges at home and abroad to measure the speed of projectile.By analyzing the basic composition and working principle of the interceptor device and the time-measuring device in the shooting method of shooting range,the thesis aims to improve the accuracy of projectile speed measurement,and design a multi-channel time acquisition system that meets the existing shooting range.Simultaneous measurement of multiple sets of velocity of the same projectile and self-calibration of the system enhance the reliability of the system itself.Aiming at the problems of low sensitivity and weak uniformity of the segmentation device in the shooting range multi-channel acquisition system,the key technologies such as projectile over-target information acquisition and signal processing are studied on the basis of photoelectric detection technology.The single-word semiconductor laser is designed as the emitted light source,and the PIN-type photosensitive diode is used as the optical curtain target of the separated structure array of the receiver,achieving a highly sensitive response to projectiles with a diameter of ?> 6mm;A threshold signal conditioning circuit composed of a photoelectric conversion circuit,a signal amplification circuit,and a comparison shaping circuit is designed.Simulation tests are performed on each of the designed circuits by Multisim is carried out.Finally,the function of the output voltage amplitude of the zone interceptor device is 5V pulse signal.In view of the problems such as low measurement accuracy,poor anti-jamming ability and poor stability in the commonly used time-measuring device,this paper introduces the design of the time-measuring device part of the range multi-channel time acquisition system,including the design of the anti-jamming circuit and the time-measuring circuit based on FPGA.Based on the principle of pulse method timing,the reasons for measuring error spree are analyzed,and a measurement method combining direct pulse counting and multiphase clock sampling is proposed,and the time-measurement range is greater than 40 ms based on FPGA technology,which uses "coarse" and "fine" time measurement methods.The timing resolution is better than the indicator requirement of 10 ns and 4 channel time acquisition at the same time.Because the light curtain target in the field work process will inevitably be disturbed by other flying objects,resulting in the phenomenon of false trigger.The system through the setting of pulse width filtering method,to select the correct projectile signal,so that the system can effectively eliminate the light components in the light curtain target to receive changes in light flux and by "flying birds,mosquitoes","shock waves" and other external factors interference.The self-developed projectile launcher is used to debug and test the segmentation device and timing device respectively.The experiments show that the performance of the system has reached the expected target,with high measurement accuracy,stable measurement performance and strong anti-jamming characteristics.