【作者】 柏思忠；

【导师】 曾孝平；

【作者基本信息】 重庆大学 ， 电路与系统， 2007， 硕士

【摘要】 电缆检测是一门兴起于20世纪八十年代的技术,它伴随着电缆的发展、兴盛而成长。其检测原理跟随着物理学,电磁学及反射理论和时频域分析理论的陆续引入而推陈出新,其技术实现方案因为电子技术的集成化而快速发展。作为市场需求,电缆检测由单一的故障检测维修发展至故障检修和日常维护;被测电缆的通信带宽由直流和基带信号到今天的高频电缆和射频电缆;电缆的种类也发展到今天的长距离电缆和短距离电缆,室内电缆和室外电缆,动力电缆和通信电缆等等多种多样。电缆检测仪也发展迅速,从操作复杂的双端检测到使用方便的单端检测;从最初使用的分立元件到使用中小规模集成电路到如今的超大规模集成电路;从需通过台式计算机协作处理发展到便携式操作甚至手持式操作;从低成本低精度发展到高精度高成本直到现在的高精度低成本小体积。电缆检测仪正在不断发展,不断更新。研究结果表明:要更好的适应市场需求电缆检测仪必须具备以下三方面特点:(1)高精度。高精度表现在两个主要方面:一方面判定的故障类型多和判断故障类型准确;另一方面检测的距离长和判定的故障距离准确;(2)小体积。微型化是仪器仪表发展的重要趋势之一,特别是在微电子集成化技术愈来愈发达的今天,由于纳米技术的生产工艺使得集成度越来越高,同时,代表当今发展潮流的片上技术的应用使得嵌入式系统也能实现复杂的算法分析。因此,高端检测仪基于上述条件同样可以实现便携式;(3)低成本。占领市场仅仅依靠高性能是不够的,较低的成本也是重要的因素。成本的降低才能实现应用的普及,居高不下的价格只能让人望而生畏。虽然上述三个条件都是必须的,但是三者同时又是相互制约的,绝对的高精度、小体积和低成本是不能同时实现的,可以合理借助和利用数学分析方法以及充分利用电子技术进行协调,使整体性能最佳。为此,引入一种新型的在时域及频域内同时分析的高解析度反射仪的实现装置——时频域反射仪。具体原理:发射一个被高斯时间包络放大的时限带限信号,该高斯包络提供时间定位,而该时限带限信号作为入射信号使得被测试系统被一个覆盖特定频段的扫频正弦波激发,利用时-频交叉关联函数和魏格纳-威利变换提供的相关检测,判定反射信号,再分析反射信号的频率偏移和时间偏移判定故障类型和故障距离。整个系统采用片上可重构技术,单一芯片完成核心控制和运算分析,通过控制外围设备而对被测试导线/电缆执行一个自动诊断,体积微型化,成本低廉。这种时-频域反射仪可被广泛应用于要求高精度测量及测试的工业领域,如:通讯、仪表检测、材料工程、半导体以及航空航天等等。该时-频域反射仪还可以为要求高解析度及精确度的智能配线系统及信号完整性问题提供一种改进的方案。另外,该时-频域反射仪还可以应用于时域反射仪(TDR)的传统应用领域,如地质/能源勘探、材料表面测试、雷达/声纳装置、通讯网络配线、光缆分析、远程勘探、流体管道泄漏检测、水位表等等。整体性能达到了高精度、小体积和低成本的要求,实现了三者的协调统一。更多还原

【Abstract】 The technology of detection cable has been come forth at 1980s,it goes from development to flourish with cable progress. On the one hand,imported physics,electromagnetics and reflection theory,and time-frequency-domain analysis theory into detection cable step by step, it’s principal has been changed with each passing day;on the other hand,it’s hardware realization has been changed rapidly based on the electronic integration technology. As for market’s demand,firstly, function of the cable detector has been changed into both defective detection and maintenance daily, replace of unique defective detection;secondly , signal bandwidth has been changed from DC and baseband to high frequency , even to radio frequency.;thirdly, diversification of cable has been obvious such as long and short , indoor and outdoor , motivity and communication and so on. So has the cable detector ,from two-end to single-end , from single component to small scale, even to super scale integrated circuit; from co-operation by computer to portable, even to handy; from low cost and low precision, high cost and high precision, to high precision and low cost. The cable detector has been changed daily to adapt to market’s require.The results show that: for the better market, the cable detector should own its character such as :(1)High precision. on the one hand , judgement the defect types and the defect distance with high precision; on the other hand, judgement the longer the distance and the more defect types. (2)Minisize bulk. micromation is one of the development trends of instruments. Especially, the more and more rapidly does the micro-electronics technology expand on the basis of Nanometer Technologies, so that the Embedded System can function the complex arithmetic and analysis rely on the System of a Chip, on the condition that excellent cable detector is prone to handy. (3) Low cost. not only excellent performance but also low cost is yet important for taking up the market. The lower of cost , the more potential to own market on the condition of the same performance.The properties of the cable detector show it is difficult to utilize three characters at one time, however reasonable using mathematics analysis and micro-electronics technology is possible in achieving the goals. Function procedure is the following: sending a time-limited and frequency-limited signal into the tested cable, at the same time, gaining time center and frequency center of the signal on the basis of time-frequency analysis and Wigner-Ville Distribution (WVD) , then checking the reflection signal rely on a time-frequency crossing relation function, at last judging the defect types and distance by calculating the time excursion and frequency excursion. The entire system is automatic measure, high performance, minisize bulk and low cost founded on the System of a Programmable Chip (SOPC). The time-frequency-domain reflector (TFDR) is abroadly applied to rigorous industry fields, for example, communication, instruments, material-engineering, semiconductor, avigation and so on. In addition, TFDR is also applied to the tradition fields of TDR, such as energy sources reconnoitering, communication net layouts, long-distance reconnoitering etc. TFDR utilizes high performance, minisize bulk and low cost, that accomplishs the development problem of principle and hardware realization on the modern times.更多还原