Get Reel Before You Install(安装前先测试一下整箱线)

Get Reel Before You Install!

安装前先测试一下整箱线

Testing and documenting newly-delivered spools can also let you determine reel-to-reel consistency to keep your cabling vendors honest. Not to mention that it can help determine the cable was mishandled during installation, refuting blame by giving you proof that all was good before installation.

测试新交付的整箱线，能确保你供应商的线是否是质量合格的产品，更何况，如果你线缆在安装的时候，安装不当导致失败，你可以通过这个测试的报告，来证明实际线缆是没有问题的。

But how do you test a 1000-meter reel of cable with no access to the far end? You may not be able to test for all parameters, but you can certain test enough to know if you should install it. Let’s review.

但是如何通过单端测试来测试305M的整箱网线呢? 你也许不能测试所有的参数，但是你可能通过单端测试的情况，大致判断，你是否去安装这个网线。让我们来看一下。

Single-Ended Copper Option
单端测试选项

When testing a spool of twisted-pair copper cabling, the latest firmware for your Fluke Network DSX CableAnalyzer? Series tester has a test option called “Single Ended Cable” available under “Other” in the test limits. But before you even get to that point, you need a way to connect the cable to the tester.

当你测试整箱线时候，你的福禄克FLUKE DSX系列（DSX2-8000或者DSX2-5000）有一项单端测试的选型（Single Ended Cable），在其他(other)的极限值，但是如果你需要这样去测试整箱线，你需要一个模块来连接你的线和测试仪。

When cable vendors test spools of cable, they use a lab adapter with their DSX. While this is the preferred method for spool testing, it’s a bit more time consuming to terminate the cable and ensure to maintain proper pair twist. Not very practical for testing dozens of reels that just showed up at the job site.

当你的线缆供应商测试整箱线时，他们也许会使用一个LABA适配器来测试，尽管对于整箱线来说，他是首选的测试方案，但是他有会消耗比较多的时间把网线和适配器链接。如果现场有很多卷线需要测试，可能它变得不是非常实用。

The easier option is to just use a field-terminated plug on the end of the spool and use a channel adapter. With a channel adapter on one end, you won’t be looking at the plug performance anyway. Note that you will get an error on your DSX as it thinks you need a lab adapter for the Single Ended Cable option. But just go ahead and continue the test.

较简单的选择是在末端选择一个适合现场的通道适配器。当你一端使用通道适配器的时候，你不用看这个RJ45接插件的性能。福禄克DSX系列的设备（DSX2-8000或者DSX2-5000）测试的时候，会提示错误。FLUKE DSX系列的设备想，你应该需要一个实验室模块DSX-LABA/002模块，在Single Ended Cable Option，但是你不用管他，直接测试就好！

When you test the reel using this method, you’ll be able to determine the distance (which is handy when you’re not sure how much cable is left on a partial reel), as well as values for near-end crosstalk (NEXT) and return loss (RL). There are a few things to consider when you’re testing a spool of cable. With a single-ended cable test, you’re not going to be able to determine insertion loss or far-end crosstalk since you’d need a remote unit on the far end for that. And you’re also not going to get very good return loss since the impedance is technically infinite with no end connection. But if your NEXT and RL fail, you’ve got yourself a “reel” problem.

当你使用这个方法测试的时候，你就有能力看到这个距离（你的网线还剩多少米），也可以看到这个近端串扰（NEXT）和回波损耗（RL）的值。当你使用单端测试的时候，有些事情，你需要考虑，你不能测试这个插入损耗和远端串扰。而且由于阻抗在无端连接的情况下在技术上是无限的，因此您也不会获得非常好的回波损耗。但是如果你的线缆NEXT和RL都失败的，你的线材可能是真的有问题。