The Locating Reflectometer

A microwave measuring instrument which is capable of producing a visual or graphical record of the reflection coefficient /spl Gamma/ along the length of a waveguide component is described. The principle of operation is the evaluation, in real time by an analog method, of the Fourier transform of /spl Gamma/ as a function of frequency, resulting in /spl Gamma/ as a function of distance.     

Microwave Reflectometer Techniques

A rigorous analysis of the microwave retlectometer is presented for what is believed to be the first time. By means of this analysis, the correct adjustment of auxiliary tuners is described, and the errors resulting from incorrect adjustments are treated in a quantitative manner. It is shown how the reflectometer technique may be further simplified while preserving the accuracy of measurement. A convenient method of adjusting the auxiliary tuners is described, sources of error are discussed, and an example is given of the calculation of error limits.     

The Six-Port Reflectometer: An Alternative Network Analyzer

Although the six-port measurement technique is rapidly gaining the attention of the microwave community, the theoretical development, to date, yields but limited practical insight into its operation. Following a brief review of the prior art, such that the six-port techniques may be placed in proper perspective, this paper presents an alternative introduction leading to much better insight, and to design criteria for a six-port circuit which optimally exploits the concept.     

A High-Resolution Swept-Frequency Reflectometer

A simple swept-frequency reflectometer is described that is capable of measuring reflection coefficients as low as 0.001 and is particularly suitable for precise impedance matching. With the exception of a length of accurate plain waveguide, used as a standard, the instrument contains no critical components and requires no tuning adjustments. The reflection coefficient is displayed on an oscilloscope or X-Y recorder on an almost linear scale that is only slightly affected by departures from square-law detection.     

The Double-Swept-Frequency Locating Reflectometer (Short Papers)

A swept-frequency-type reflectometer is newly developed which is capable of measuring the distances to the reflection locations and reflection magnitudes in the coaxial line or waveguide, using a double-swept-frequency (DSF) source and a bandpass filter. The principle of this reflectometer and experimental results obtained at 2 GHz are given.     

HP8147光时域反射计（OTDR）的使用

随着光纤技术的不断发展 ,全国各地的有线电视网络都开始利用光缆对旧电缆网进行改造。在改造和维护的过程中 ,我们往往需要了解一些出现在链路、链路末端或折断处的部位 (距离 )、链路中光导纤维的衰减 ,以及连接体所致反射 (或返回损耗 )的大小等链路的重要特性。为此 ,我局较早购置了一台ＨＰ8147光时域反射计 ,通过几年来的使用 ,我们发现该机性能优越 ,使用灵活 ,在光纤改造及维护中发挥了较好的作用。下面就该机的一些主要功能及相应操作方法作一些介绍 ,供同行参考。1　测量前的准备1.1　连接光导纤维将光纤连接至ＯＴＤＲ ,步骤和方…     

手持式光时域反射计

介绍了一个由MCU,激光器,LCD和高速A／D等芯片构成的光纤测量系统,该系统具有单键操作,价格低廉,功能齐备等优点,该产品科技含量高,参照Bellcore的标准,填补了国内开发市场的一项空白。     

Band-Limited Deconvolution of Locating Reflectometer Results

The locating reftectometer is a frequency-swept microwave instrument which, by analog Fourier transformation, converts the reflection coefficient, a function of frequency Gamma(s), into the spatial distribution of the reflection coefficient Gamma(x). It will be shown that by the method of deconvolution an increase in axial resolution may result. By making use of the fact that the real and imaginary parts of the "locating plot" Gamma(x) are a Hilbert transform pair, a signal-to-noise ratio improvement is achieved by averaging the results of complex deconvolution using only the real and then only the imaginary parts of the locating plots. A number of experimental results are given, illustrating the increase in axial resolution when the method of band-limited deconvolution is applied to some typical waveguide components and obstacles.     

光时域反射仪(OTDR)的研制

研制出了一台初步达到市场商品化标准的光时域反射仪.阐述了光时域反射仪的工作原理和制作方法,对它的每个组成部分,包括光器件、电子器件以及测量软件都做了说明.通过对光纤样品的测量,分析了这台光时域反射仪的功能与测量效果.     

A 94-GHz Diode-Based Single Six-Port Reflectometer

This paper describes design considerations and gives measurement results for a single six-port reflectometer constructed from WR-10 waveguide with silicon Schottky diode detectors. Tradeoffs between various types of power detectors are discussed along with criteria for six-port junction design. The merits of two calibration procedures are compared. Measurements at 94 GHz indicate good agreement between expected and experimental values of q-points and of a sliding mismatch with nominal 0.1 reflection coefficient.     

一种新的双魔T多状态反射计

介绍了一种新的多状态反射计。该反射计由两只魔T和两个功率检测器组成。采用一只精密滑动短路器作标准,通过任意相位单位矢量五点校准法对其进行校准;另用一只精神滑动短路器来改变反射计状态。测量复反射系数采用矢量变换法。与传统的六端口反射计与多状态反射计相比,该反射计校准端口与测试端口相分离,具有结构简单、稳定性高、易于实现的特点。     

The Measurement of Complex Reflection Coefficient by Means of a Five-Port Reflectometer

A detailed analysis of the five-port reflectometer is presented in this paper. The possibility and application limitation of using a five-port to measure complex reflection coefficients is discussed and the related design consideration is derived. From the poiut of view of minimum measurement error, an optimized, multi-octave five-port circuit is suggested and realized by ordinary microwave integrated circuit technology. Some measurement results are reported to prove the above analysis and design consideration.     

波长扫描型布里渊光时域反射仪

布里渊光时域反射仪(BOTDR)是一种具有广泛应用前景的分布式光纤传感器。对于特定的入射波长,自发布里渊散射光的布里渊频移与温度和应变成线性关系,通过测量光纤沿线布里渊频移分布可实现温度或应变的分布式传感。布里渊功率谱扫描是BOTDR获取布里渊频移的常用手段,已有光频差扫描与电频扫描两种方式。基于布里渊频移对波长的依赖性,提出一种波长扫描型BOTDR。采用可调谐激光器作为光源,通过扫描入射光波长,来获取布里渊功率谱,该方法兼具光频差扫描与电频扫描的优点。实验证明了该方法的可行性,对23.4km光纤进行测量,实现了5m的空间分辨率与2.2℃的温度测量精度。     

长距离高精度的线性调频光时域反射仪

为了对西藏人烟稀少地区和单跨段传输距离很长的光纤链路进行检测,文章提出一种用于提高线性调频(LFM)光时域反射仪(OTDR)空间分辨率和测量距离的方法。该方法通过产生一个调频范围为200 MHz、脉冲宽度为20μs的强度调制模拟LFM信号来实现高的空间分辨率和大的探测距离。使用该方法在西藏地区的实际光纤传输链路中进行了实验测试,实验结果表明,该方法能够在长度为240 km的光纤链路上实现0.000 53 km的空间分辨率,与相同测量参数的单脉冲OTDR相比,动态范围提高了8.5 dB。     

用微波网络分析仪组成毫米波反射计测试系统

介绍了用微波网络分析仪组成的毫米波反射计测试系统，以及系统校准，误差修正的理论和技术，并给出了实际系统的测量结果。     

一种具有迈克耳逊结构的新型光时域反射仪

利用传输光纤中后向瑞利散射光携带有光纤位置、外界振动等信息的特点,采用光纤迈克耳逊结构构成干涉型光时域反射仪,有望以分布方式传感沿光纤的微小振动信号.文中设计了一种新型结构的分布式光纤振动传感器,该传感器用3dB耦合器将波长为1310nm的红外激光分为两路相干光:参考光和传感光,它们中的后向瑞利散射光在耦合器处发生干涉,干涉信号的变化点对应于振动点所在的位置.将没有振动信号、加微小振动信号和加损耗干扰三种情况分别作用于传感光纤并进行了试验对比.结果表明,在微小振动的情况下,光强变化微弱;加损耗时,光强变化显著,定位准确.     

Chaotic Correlation Optical Time Domain Reflectometer Utilizing Laser Diode

We propose a novel technique for chaotic correlation optical time domain reflectometer with millimeter and range- independent spatial resolution. Utilizing chaotic waveforms generated from a laser diode with an optical fiber ring feedback, a proof-of-concept experiment is demonstrated with 6-cm spatial resolution in the 0$sim$140 m range, which is limited by the bandwidth of the real-time oscilloscope used.      

An Automatic Network Analyzer Using a Slotted Line Reflectometer

An automatic network analyzer (ANA) based on a 5-port reflectometer is presented. The measuring circuit consists of a slotted waveguide with sliding probe. A group of three fixed probes may be used instead. A microwave source, frequency counter, and power meter are used all controlled by a desktop computer. The theory is simple and the algorithm for obtaining the complex reflection coefficient from experimental data is fast. Some results are given for measurements earned out at X-band frequencies. Successful measurement accuracy is achieved with relatively noncomplex hardware. Multioctave bandwidth operation is expected for the proposed technique.     

Calibrating the Six-Port Reflectometer by Means of Sliding Terminations

The six-port technique promises to have a major impact on the next generation of automatic network analyzers because complex heterodyne methods may be replaced by simple amplitude detectors. This projection, however, is predicated upon the existence or development of calibration techniques which permit one to conveniently and accurately obtain the parameters which characterize the six-port. This paper describes a number of substantial refinements to a previously described procedure which is based upon the use of sliding terminations.