基于FPGA的靶场高精度时间采集系统设计

Design of High Precision Time Acquisition System for Shooting Range Based on FPGA

弹丸的飞行速度是衡量轻武器毁伤效能和弹道特性的重要特征之一。针对在靶场测试中弹丸飞行速度测试问题,采用以区截装置和高精度测时相结合的方式测量弹丸速度。为了提高测速精度,在光幕靶测试原理基础上,设计了以FPGA为核心的高精度时间采集系统。对经过两靶间弹丸飞行时间间隔进行“粗”(直接脉冲计数法)、“细”(时钟数字移相法)相结合的精密测量,利用双锁相环级联、高精度内插时钟技术,实现了同时扩大计时范围和提高计时精度的目的。实验结果表明,所设计的时间采集系统测量最大时间间隔为83.89 ms,测量精度为312.5 ps,并通过软件实现了光幕靶测速时,去除冲击波、蚊虫飞鸟、外界光线的干扰问题,达到了靶场时间采集大范围、高精度、抗干扰性强的使用要求。

The flying speed of the projectile is one of the important characteristics to measure the damage efficiency and ballistic characteristics of light weapons.In this paper,the projectile speed was tested in the combination of the section cutting device and the high-precision time measurement.In order to improve the speed measurement accuracy,based on the light curtain target test principle,a high-precision time acquisition system with FPGA as the core was designed.Precise measurement of“coarse”(direct pulse counting)and“fine”(clock digital phase shifting)through the time interval between two targets were obtained by using double-phase-locked loop cascade and high-precision interpolation clock technology.The purpose of simultaneously expanding the timing range and improving the timing accuracy was achieved.The experimental results showed that the time interval of the time acquisition system designed in this paper was 83.89ms;the measurement accuracy was 312.5 ps;and the impact of the shock wave,mosquitoes and external light was achieved by the software.Time collection required a wide range,high precision,and strong anti-interference requirements.