一种改进的环形线圈车速测量平台设计与实现

介绍了一种改进的环形线圈车速测量平台。该系统平台主要依据车辆通过两个环形线圈时，经过检测器的整形，得到两个不同时刻的宽脉冲，再经过CPLD分频、计数，然后把所采集的数据通过PCI总线送入到工控机中进行处理，得到车辆通过环形线圈时的频率变化波形。最后利用波形的相关性，得到同一车辆经过两个线圈时的时间差，利用速度公式，得出车辆的速度。

The Design and Realization of an Improved Detecting Speed System of Loop Sensors

This paper introduces an improved detecting speed system of Loop Sensors. When vehicle passing through the Loop, sine wave signal collected by Loop Sensors is converted square wave, then divided and counted by CPLD, then the signal put into PC. By analyzing high frequency pulse in a time, we can obtain curves when vehicles passing through the Loop Sensors. By wave self-correlation analysis, we can get time difference when car passing by two Loop Sensors. At last, we can get the speed.