Vehicle tester with ring sensor

Abstract

A vehicle detector comprising a loop sensor, phase lock loop PLL, frequency change detector, and a micro-processor including a logic circuit. Output of the PLL and the frequency change detector is inputted to the logic circuit, and the logic circuit performs logical OR operation of the output of the PLL and the output of the frequency change detector. The output of the logic circuit is used as a vehicle detection signal.

Description

technical field [0001] The present invention relates to a vehicle detector using a loop sensor, and more particularly to a vehicle detector using a loop sensor including a frequency change detector for detecting a low-speed vehicle. Background technique [0002] The vehicle detector using the ring sensor in the prior art will first be described below. [0003] figure 1 is a schematic diagram of a prior art vehicle detector using a ring sensor. [0004] figure 1 The vehicle detector using the loop sensor detects the passing of the vehicle according to the change of the resonant frequency caused by the change of the loop inductance generated when a conductor passes through the loop 11 . This vehicle detector uses a PLL 12 and a detection circuit 13 in order to detect a change in resonance frequency and output a vehicle detection signal. The operation of the PLL will be described below. [0005] figure 2 is the block diagram of the PLL. A PLL (Phase Locked Loop) is a re...

AI Technical Summary

Problems solved by technology

A low-speed vehicle passing the loop sensor in this manner may cause the loop sensor to output several signals that appear to be generated by the passing of several high-speed vehicles, thus detrimental to accurate detection

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