Patent ID: 9679478
Date: 2017-06-13
CPC Classifications: G08G

Claim:
1. An online traffic volume monitoring system based on a phase-sensitive optical time domain reflectometry, comprising: sensing fiber cables buried along a road, a phase-sensitive optical time domain reflectometry and a signal processing unit; wherein the phase-sensitive optical time domain reflectometry comprises an ultra-narrow line-width laser, an acousto-optic modulator (AOM), an erbium-doped fiber amplifier (EDFA), an optical isolator, a circulator, an optical filter, a photoelectric detector (PD), an analog-digital converter (ADC) and a waveform generator; wherein the ultra-narrow line-width laser generates a continuous coherent light; the AOM modulates the continuous coherent light into an optical pulse signal; the optical pulse signal is amplified by the EDFA and then gated into the sensing fiber cable through the optical isolator and the circulator from a first port to a second port; Rayleigh scattering light is generated when the optical pulse signal is transmitting through the sensing fiber cable, wherein backscattered Rayleigh optical signal returns through the second port to a third port of the circulator and then is filtered by the optical filter to eliminate noise; after a photoelectric conversion by the PD, an analog optical time domain reflection signal is obtained and then converted into a digital signal by the ADC; the digital signal is then transmitted into the signal processing unit in real time; the waveform generator is for generating periodic pulse signals which are used as driving signals of the AOM for modulating the continuous coherent light, outputted by the ultra-narrow line-width laser, into the optical pulse signal, and also used as triggering signals of the ADC for periodically acquiring the optical time domain reflection signal simultaneously.