基于磁感线圈的车流量检测的研究

为了解决车辆计数问题，将环形线圈作为传感器，铺设在公路行车道上。当车辆通过线圈上面时，由于电感L发生变化，引起振荡电路的频率发生变化；通过锁相环芯片检测频率的变化，使模拟信号转化成数字信号，将锁相环产生的输出信号传入单片机；当单片机检测到锁相环的输出电平由高变到低时，便计数一次，从而完成对车流量的检测。在检测模型的测试中，该系统表现出较快的检测速率和较低的误检率，具有一定的抗干扰能力。

Traffic flow detection based on magnetic coils

The ring coil taken as a sensor is laid on the highway to count the vehicles passed by.When vehicles run through above the coil,the variation of inductance L causes the frequency of the oscillating circuit changes.The frequency variation is detected by the chip on the phase-locked loop.The analog signal is converted to digital signal.The output signal produced by the phase-locked loop is transmitted to the microcomputer.It counts once when output electrical level changes from high to low,thus the traffic flow detection is completed.In the detection model testing,this system showed a fast detection rate and low false alarm rate.It has a certain anti-jamming capability.