基于光纤相干背向瑞利散射的列车实时定位技术

Real-time positioning technology of train based on optical fiber coherent Rayleigh backscattering

随着中国铁路里程跨越式增长,铁路货车重载化程度不断提高。利用铁路沿线既有通信光缆提出了一种基于光纤中背向瑞利散射信号干涉技术,光纤发生细微振动时,会导致扰动位置的光纤相位及折射率发生变化从而产生背向瑞利散射光。对前后时刻瑞利信号曲线进行差值运算,差分曲线上干涉光强信号发生变化的位置,对应扰动发生的位置,从而实现对铁路车辆的识别和定位,通过采集振动信号的时频特性域信号进行分析,提取信号强度、列车长度和车厢个数等特征,对车型进行精确识别。该技术与传统定位技术相比,可以实现长距离监测,且传感光纤埋藏于铁路两旁的地下,有利于光纤的隐蔽和保护。实验测试结果表明,系统对列车位置的定位误差在±10 m内,可以实现25 km内对列车速度以及位置的监测。

With the rapid growth of railway mileage in China, the degree of heavy load of railway wagons continues to increase. An interference technology based on Rayleigh backscattering signal in optical fiber was proposed by using existing communication optical cables along railway lines. When the fiber vibrated slightly,the phase and refractive index of the fiber at disturbed position changed, which resulting in the Rayleigh backscattering light. By performing differential calculation on the Rayleigh signal curves before and after the operation, the location of the interference light intensity signal corresponded to the location of the disturbances was obtained. Based on this method, the recognition and positioning of railway vehicles were realized. By collecting and analyzing the time-domain and frequency-domain signal, the signal strength, train length, the number of carriages and other characteristics were extracted, and the model of railway vehicles were accurately recognized. Compared with traditional positioning technologies, this technology could realize long-distance monitoring, and the sensing fiber was buried underground on both sides of the railway, which was conducive to the concealment and protection of optical fiber. Experimental results show that the positioning error of the system is within ±10 m, and the detection of railway speed and position within 25 km can be realized.