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福禄克FLUKE DSX系列（DSX-5000,DSX-8000)测试同轴电缆解决方案

When it comes to copper testing, we talk a lot about category balanced twisted-pair copper cabling like Category 6, Category 6A and Category 8. And although this cabling type is widely deployed to support everything Ethernet transmission of voice, data and video, that doesn’t mean it’s the only copper cabling you could encounter.

当谈到通缆测试的时候，我们大部分都是讨论双绞线的测试，例如：CAT6，CAT6A和CAT8。尽管这类布线类型已经广泛用于部署语音、数据和视频网络传输，但这并不意味着你只会面临这类布线系统。

Coaxial cabling (sometimes just “coax” for short) has long been used for distribution of data and video signals, and it was one of the first media to support Ethernet with 10BASE2 and 10BASE5 that transmitted 10 Gb/s up to 185 meters or 500 meters, respectively. The term “coaxial” refers the fact that the cable’s center conductor and shield share the same axis, or center point. Some coaxial cable may include multiple shields, such as a quad shielded coax that includes two layers that each consist of a braided shield over a foil shield. It’s the shielding that makes coaxial cable highly resistant to electromagnetic interference and able to carry high frequency signals over long distances.

同轴电缆布线很长一段时间用来传输数据和视频信号，它也是第一批支持10Base2和10Base5（10Base2 在185m可以数据达到10Gb/s ，10Base5在500m可以达到10Gb/s），“同轴”的意思是电缆的中心导体和屏蔽共用同一轴线或中心点。一些同轴电缆也许包含多层屏蔽，例如：四屏蔽同轴电缆，该同轴电缆包括2层，每一层由箔屏蔽上的编织屏蔽组成。正是这种屏蔽使得同轴电缆具有高度抗电磁干扰的能力，并能够在长距离上传输高频信号。

While we often think of coax as being only deployed in residential applications for broadband video and cable TV (CATV), it can still be found in commercial enterprise environment for everything from closed circuit television (CCTV), audio and video, to radio antenna and even some network connections. It therefore makes sense to understand this cable media and how to test it.

虽然我们通常认为同轴电缆仅部署在宽带视频和有线电视(CATV)的住宅应用中，但是它仍然可以在商业企业环境中找到，从闭路电视(CCTV)、音频和视频、到无线电天线甚至一些网络连接。因此，理解这种同轴电缆和如何测试它是有意义的。

The Primary Types

主要类型

There are several different types of coax cables to support a wide range of specialty applications, such as satellite communications, industrial, military and marine applications. The three most common non-industrial coax types are RG6, RG11 and RG59, with RG6 being the most common type you will likely encounter in the enterprise for applications like CCTV and CATV. RG11 has a larger center conductor than RG6, which means it has lower insertion loss and can transmit signals further than RG6. However, thicker RG11 cables cost more and are extremely inflexible, making them impractical for deployment in premise applications and better suited for use in longer-run outside plant installations or for straight backbone links. RG59 is more flexible than RG6, but it features even higher loss and is rarely used anymore except in low-bandwidth, low-frequency analog video applications where distances are short and pathway space is limited (think back-up camera in your car).

有几种不同类型的同轴电缆，以支持广泛的专业应用，如卫星通信，工业，军事和海洋应用。最常见的三种非工业同轴电缆类型是RG6、RG11和RG59，其中RG6是您在企业中可能遇到的用于CCTV和有线电视等应用的最常见类型。RG11具有比RG6大的中心导体，这意味着它具有更低的插入损耗，并且可以比RG6发送更多的信号。然而，较厚的RG11电缆成本更高，并且极其不灵活，使得它们不适合部署在房屋应用中，并且更适合于在长时间运行的外部工厂安装或用于直骨干链路。RG59比RG6更灵活，但是它具有更高的损耗，并且除了在低带宽、低频的模拟视频应用中（距离很短并且路径空间有限）之外，很少再使用它（想想你车中的备用摄像机）。

Coaxial cables also come in various impedances—typically 50, 75 and 93 ohm. 50 ohm coaxial offers higher power handling and is primarily used for radio transmitters like Ham radios, CBs and walkie-talkies. 75 ohm cable does a better job of maintaining signal strength and is primarily used for connecting any type of receiving device such as CATV receivers, high-definition TVs and digital recorders. Originally used in mainframe IBM networks in the 1970s and early 1980s, 93 ohm coax is rare and expensive. While 75 ohm coax is likely the impedance you will encounter in most present-day applications, it’s important to note that all components in a coaxial cabling system should have the same impedance to avoid internal reflections at connection points that can cause signal loss and poor video quality.

同轴电缆也有各种阻抗，通常为50, 75欧姆和93欧姆。50欧姆同轴提供更高的功率处理，主要用于无线电发射器，如无线电台，广播和对讲机。75欧姆电缆在保持信号强度方面做得更好，主要用于连接任何类型的接收设备，如有线电视接收机、高清电视和数字记录器。最初在20世纪70年代和80年代初的大型IBM网络中使用，93欧姆同轴电缆是罕见的和昂贵的。虽然75欧姆同轴电缆可能是您在当今大多数应用中遇到的阻抗类型，但需要注意的是，同轴电缆系统中的所有组件都应该具有相同的阻抗，以避免在连接点处出现内部反射，从而可能导致信号丢失和视频质量下降。

Digital Signal 3 (DS3) signals used to carry traffic in central offices (also referred to as a T3 line) also use coaxial cable, including 75 ohm Type 735 and Type 734. Type 735 cable can be used to cover distances up to 69 meters, while Type 734 cable can be used up to 137 meters. RG6 cable may also be used to carry DS3 signals but over shorter distances.

数字信号3(DS3)信号用于在中央办公室承载业务(也称为T3线路)也使用同轴电缆，包括75欧姆735型和734型。735型电缆可以用来覆盖69米的距离，而734型电缆可以使用到137米。RG6电缆也可用于承载DS3信号，但在更短的距离。

Testing Made Easy

测试容易

对于任何同轴电缆，安装的成功依赖于使用高品质的元件和正确的安装方法，尤其是连接器的安装。Insertion loss, which is affected by the overall length of the installed link, is the primary parameter that ensures coaxial cabling will support the intended application.

ANSI/TIA-568-4.D specifies requirements for 75 ohm broadband coaxial cabling, cords and connecting hardware to support CATV, satellite television and other broadband applications. For the Cabling Subsystem 1 between the outlet and the first distribution point, the length limit is 46 meters for RG6 and 90 meters for RG11. For a Cabling Subsystem 2 between distribution points, the length limit remains at 46 meters for RG6 and increases to 100 meters for RG11. For each of these deployments, TIA-568-4.D specifies insertion loss limits over the frequency range of 5 to 1002 MHz.

按照ANSI / TIA 568 – 4.D标准75欧姆同轴宽带布线，支持有线电视、卫星电视和其他宽带应用。对于布线子系统，长度限制是46米和90米RG6 RG11为中心。fo布线子系统2点之间的长度分布，限制仍然在46米for RG6 RG11和增加到100米。for each of these deployments，TIA 568 – 4.D指定插入损耗范围为5Mhz至1002Mhz。

Testing is made easy with Fluke Networks’?DSX-CHA003 Coax Adapter for use with?DSX CableAnalyzer? Series Copper Cable Certifiers. With support for RG6 and RG11 coaxial cabling, the DSX-CHA003 Coax Adapter tests to the TIA insertion loss limits over the full frequency range. Because insertion loss is strongly influenced by the length of the installed link whereby a shorter link may pass even when performance has been significantly degraded by cable damage or poorly installed connectors, the DSX CableAnalyzer also provides Length-Scaled test limits that automatically adjust insertion loss limit based on the actual measured length of the cabling segment.

使用Fluke Networks的DSX-CHA003同轴适配器进行测试很容易，该同轴适配器用于DSX电缆分析仪系列铜电缆认证。在RG6和RG11同轴电缆的支持下，DSX-CHA003同轴适配器在全频范围内测试TIA插入损耗极限。因为插入损耗强烈地受到所安装的链路的长度的影响，因此即使由于电缆损坏或连接器安装不良而导致性能显著下降，较短的链路也可能通过，所以DSX CableAnalyzer还提供了长度缩放的测试限制，该测试限制自动进行广告。基于电缆段实际测量长度的插入损耗极限。

The DSX CableAnalyzer also provides Length-Scaled DS-3 test limits for Type 734, Type 735 and RG6 coaxial cabling used in central office applications. And while only encountered in rare lower-speed applications where a distance greater than 100 meters is required, the DSX CableAnalyzer can also test 50 ohm coaxial cabling used to support legacy 10BASE2 or 10BASE5 Ethernet.

DSX电缆分析仪还提供了用于中央办公室应用的734型、735型和RG6型同轴电缆的长度缩放DS-3测试标准。虽然只在需要大于100米的距离的罕见的低速应用中遇到，但是DSX电缆分析仪还可以测试用于支持传统10BASE2或10BASE5以太网的50欧姆同轴电缆。