基于GPS的破片测速多设备同步触发方法

Multi-device Synchronous Triggering Method Based on GPS for Fragmentation Speed Measurement

针对破片测速多设备同步触发时易误触发,布线困难等问题,提出了一种基于GPS的破片测速多设备同步触发方法。利用GPS高精度的秒脉冲和通用异步收发传输器(UART)时间信息周期性的同步设备系统时间;使用现场可编程门阵列(FPGA)作为控制芯片,使用高精度晶振作为基准时钟,进一步降低误差。理论分析了在30 s同步一次情况下,双设备时间误差最大为8. 4μs,长时间GPS不同步时多台设备累积误差到达1 ms时间为59 min。利用示波器对GPS模块的秒脉冲信号精度做了验证,证明两个GPS模块秒脉冲之间误差在50μs以内。最后使用数据采集仪采集同一周期性三角波,设置为GPS触发方式。两台设备在同一时间触发,观察采集到的波形,两台设备的时钟误差在20μs以内,验证了方案的可行性。

Aiming at the problem that the fragmentation speed multi-device synchronous triggering is easy to trigger,and the wiring is difficult,a GPS-based fragment triggering multi-device synchronous triggering method is proposed.Periodically synchronize device system time with GPS high-precision time pulse and universal asynchronous receiver/transmitter(UART)time information.Using the field-programmable gate array(FPGA)as the control chip and using the high-precision crystal as the reference clock further reduces the error.Theoretical analysis shows that the maximum time error of the dual device is 8.4μs in the case of 30 s synchronization.When the GPS is not synchronized for a long time,the cumulative error of multiple devices reaches 1 ms in 59 min.Using the oscilloscope to verify the accuracy of the GPS module s time pulse signal,it is proved that the error between the two GPS module time pulse is within 50 ns.Finally,the same periodic triangular wave is collected by using the data acquisition instrument,and the GPS trigger mode is set.The two devices are triggered at the same time to observe the acquired waveform.The clock error of the two devices is less than 20μs,which verifies the feasibility of the solution.