Fiber-optic reflection measurements using OCWR and OTDR techniques

A method for determining the backscatter and reflection responses of an optical fiber and reflector to an arbitrary input is developed. Two cases are specifically considered: a continuous-wave input and a rectangular pulse input. From the rectangular pulse input response, the equation is derived for computing the reflectance of a discrete component from an optical time-domain reflectometer (OTDR) measurement. Precautions are given for accurately performing reflectance measurements using an OTDR. Two methods are presented for determining the backscatter level of the fiber type under test, and its importance in reflection measurements is shown     

基于VMD与SSA的OTDR信号去噪算法

为对光时域反射计(Optical Time Domain Reflectometer, OTDR)数据进行去噪处理,提出了一种基于变分模态分解(Variational Mode Decomposition, VMD)与奇异谱分析(Singular Spectrum Analysis, SSA)的去噪算法。首先,对OTDR数据进行VMD分解;然后根据相关系数准则判定有效分量,并采用SSA对与原信号相关系数较小的分量进行处理;再对所有分量求和,得到重构后的信号,从而实现数据信噪比的提高。经实验验证,该算法的去噪效果良好,容易实现,具有较大的实用价值。     

基于OTDR技术的高压输电导线断股和损伤检测

为了保证高压输电线路的正常运行,及时准确地 对输电导线的断股、损伤进行检测,提出了一种应用光 时域反射仪(OTDR)技术对输电导线断股、损伤进行分布式光纤传感检测的方法。基于OTDR技 术搭建了利用钢管模拟输电导线的模拟损伤试验系统,进行了高压输电导线断股、损伤 实物试验。高 压输电导线断股、损伤模拟试验及实物试验的结果表明,应用OTDR技术可以有效地识别出高 压输电导线的断股、损伤,并能够对损伤部位进行精确地定位。     

利用OTDR进行精确的测试

从理论上推导了OTDR测试光纤长度、衰减常数、衰减、接头损耗、回波损耗的原理 ,并在此基础上分析了影响OTDR测试精度的因素以及OTDR测量误差的来源 ,最后指出了在利用OTDR进行测量时应注意的地方。     

Long dynamic range spread spectrum optical domain reflectometer

The performance of an optical time domain reflectometer (OTDR) is significantly improved using spread spectrum technology. The concept of spread spectrum OTDR (SSOTDR) is proposed, the theoretical basis and simulation results of the new method are given, and the problem of direct application of bipolar spread spectrum codes to OTDR and despreading in the optical domain are solved. The simulation results show the feasibility of the SSOTDR, which exhibits better dynamic range reported to date for a practical long-haul OTDR system without using conventional average technique.     

Measuring the individual attenuation distribution of passive branched optical networks

We propose a new method for measuring the individual attenuation distribution of passive branched optical networks and describe our experimental results. This test method employs two techniques. One is a passive optical distribution technique, whereby communication light is uniformly distributed to all branched fibers, and test lights are distributed to each branched fiber according to their wavelength. The other is an attenuation distribution measurement technique using an optical time domain reflectometer (OTDR) which can control the test light wavelength.     

OTDR应用于PON ODN测试与诊断分析

光宽带的规模建设带来了接入网光纤光缆的海量建设,大建设应用后重点在于光网运营维护管理,因而高效的光网检测手段及其相关的灵活应用方式非常重要.在分析ODN组网基础上,研究OTDR应用于ODN的测试能力,重点分析了OTDR测试中ODN关键事件的特征,同时根据ODN建设模式和OTDR检测缺点,针对性提出了相关应用方案.     

新型光时域反射计在无源光网络中的应用

提出并实验验证了一种利用自主研制的OTDR来有效定位PON的支路断点或异常损耗事件的方法,讨论了在PON的测量中OTDR面临的新问题和新要求.     

小波算法在光纤测量中的应用

分析了OTDR工作的理论基础和主要原理,对OTDR中的技术难点进行了阐述,并提出了一种基于小波算法的解决方案,目的是对OTDR信号中的噪声进行滤波和信号中的事件点进行精确定位。经过理论论证和实践数据表明,该方法是一种可行的方案     

GIS在通信光缆故障定位中的应用

针对通信光缆故障点地理空间位置判断困难,本文提出了一个基于地理信息系统(GlS)的光缆故障点判断方法。根据光时域反射仪(OTDR)的基本工作原理及其在光缆故障点测量中的应用,结合通信光缆维护的具体特点和要求,建立了一个光缆沿途区域的GIS系统,并提出了一个基于GIS和OTDR测量值的光缆故障点确定算法,提高了光缆维护工作的维护效率。     

Real-time long range complementary correlation optical time domainreflectometer

The improved performance of an optical time-domain reflectometer (OTDR) through the application of a correlation technique using codes with complementary autocorrelation properties is discussed. The theoretical foundations of the method are presented along with experimental results exhibiting the best one-way range reported to date for a practical long-haul, long-wavelength OTDR system     

Novel OTDR Technique for Measuring Relative-Index Differences of Fiber Links

A novel technique is proposed for measuring the relative-index difference of the fiber links using an optical time-domain reflectometer (OTDR). The material dispersion of the fiber links can be estimated by using this method. Moreover, the chromatic dispersion distribution of a fiber link is successfully estimated by combining this technique with the conventional OTDR technique     

在最小二乘法模式下幻峰对OTDR测试光纤接头损耗的影响

描述了幻峰及其对OTDR测试光纤线路的影响,重点从理论上分析了OTDR在“最小二乘法”模式下的工 作原理,并对OTDR在“最小二乘法”模式和“两点法”模式下测试光纤接头损耗进行了比较。     

Resolution enhancement in long pulse OTDR for application in structural health monitoring

To improve the range resolution in inexpensive conventional long pulse optical time domain reflectometer (OTDR) for application in structural health monitoring (SHM) and robotic neural network, the Fourier Wavelet Regularized Deconvolution (ForWaRD) based on the adaptive wavelet method is employed. Since Deconvolution is a noise sensitive process, employing the (ForWaRD) method enhances the signal to noise ratio. Simulation for long pulse OTDR system is done and ForWaRD method is employed to improve the resolution of the OTDR system to the order of several centimeters. In this method the resolution is limited by the bandwidth of detector, bandwidth of electronic circuit, and the sampling rate of analog to digital convertor.     

背向散射差异与光纤接头损耗的OTDR测试

本从OTDR测试原理出发，分析了OTDR测试光纤熔接损耗时背向散射差异的影响，通过实验分析了模场直径与背向散射差异的关系。根据模场直径分布，对光缆工程中OTDR单向测试结果进行了估计，并据此讨论了工程施工中熔接水平的简单判断方法。     

光模块内置OTDR数据及格式分析

为了满足日益增多的PON 的网络光纤检测需求,光模块内置OTDR 技术正在不断地发展完善,提出了基于光模块内置OTDR的PON系统架构中OTDR相关接口的数据传输接口功能和数据分析功能,确定了OTDR数据文件结构,分析梳理了OTDR的数据内容,定义了OTDR的数据格式,目的是能够实现通用的内置OTDR数据格式,促进内置OTDR技术产业发展成熟。     

A novel in-service measurement technique using the same wavelength band as SCM signals

This paper proposes a new technique for measuring in-service optical fibers, that uses an optical time domain reflectometer (OTDR). The feature of the proposed technique is that the OTDR light is in the same wavelength band as the video signal, which is distributed by using the subcarrier multiplexing (SCM) technique. In a 40-channel SCM system operating at a signal wavelength of 1.558 /spl mu/m, we show that the required video quality can be maintained, by using the proposed OTDR operating in the 1.55 /spl mu/m band, even though the measured fiber is in service and the OTDR light enters an optical receiver. Moreover, we clarify the conditions for undertaking measurements, without the need for optical filters designed to prevent OTDR light from degrading the SCM signal quality.     

High-accurate fault location technology using FSK-ASK probebackscattering reflectometry in optical amplifier submarine transmissionsystems

This paper proposes a new modulation format for optical time domain reflectometry (OTDR) to eliminate optical surge and improve OTDR performance in optical amplifier submarine transmission systems. The modulation format, FSK-ASK, uses a short high-power probe pulse and a long dummy pulse. Thanks to the slow gain dynamics of erbium-doped fiber amplifiers, both pulses experience an identical gain, equal to the loss of a span, so that the probe pulse maintains its high power and does not develop into an optical surge. Fault location experiments verify a theoretical prediction that FSK-ASK improves the signal-to-noise ratio (SNR) of OTDR by an amount as large as the power ratio of the probe to dummy signal. They also confirm the elimination of the optical surge caused by conventional OTDR using a solitary probe pulse. An FSK-ASK OTDR is applied in a commercial submarine amplifier transmission system which has a total transmission length of 890 km and a repeater spacing of 90 km. These field trial results show that subtle fiber anomalies can be located, with a spatial resolution of 1 km, along the entire length of the amplifier transmission system from a terminal end     

Low-cost high-resolution time-domain reflectometry for monitoringthe range of reflective points

A new OTDR technique to interrogate the range of reflective markers in an optical fiber (or an electrical cable) is presented. The technique has been developed to monitor strain in sections of a fiber over gauge lengths of several meters. Signal-to-noise analysis shows that current OTDR systems do not fully exploit the spatial resolution theoretically available. The available resolution is explored with a new OTDR technique     

一种基于小波变换的OTDR事件分析算法的研究

简单分析了用 OTDR卡进行光纤检测的原理 ,根据小波分析检测信号突变点的理论 ,提出了运用小波分析对光纤断点及反射事件准确定位的方法。理论分析和实例计算表明 ,这种方法对 OTDR曲线中反射事件尤其是断点的定位非常准确 ,是一种行之有效的方法