Get Reel Before You Install(安裝前先測試一下整箱線)

Get Reel Before You Install!

安裝前先測試一下整箱線

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.

測試新交付的整箱線，能確保你供應商的線是否是質量合格的產品，更何況，如果你線纜在安裝的時候，安裝不當導致失敗，你可以通過這個測試的報告，來證明實際線纜是沒有問題的。

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.

但是如何通過單端測試來測試305M的整箱網線呢? 你也許不能測試所有的參數，但是你可能通過單端測試的情況，大致判斷，你是否去安裝這個網線。讓我們來看一下。

Single-Ended Copper Option
單端測試選項

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.

當你測試整箱線時候，你的福祿克FLUKE DSX係列（DSX2-8000或者DSX2-5000）有一項單端測試的選型（Single Ended Cable），在其他(other)的極限值，但是如果你需要這樣去測試整箱線，你需要一個模塊來連接你的線和測試儀。

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.

當你的線纜供應商測試整箱線時，他們也許會使用一個LABA適配器來測試，盡管對於整箱線來說，他是首選的測試方案，但是他有會消耗比較多的時間把網線和適配器鏈接。如果現場有很多卷線需要測試，可能它變得不是非常實用。

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.

較簡單的選擇是在末端選擇一個適合現場的通道適配器。當你一端使用通道適配器的時候，你不用看這個RJ45接插件的性能。福祿克DSX係列的設備（DSX2-8000或者DSX2-5000）測試的時候，會提示錯誤。FLUKE DSX係列的設備想，你應該需要一個實驗室模塊DSX-LABA/002模塊，在Single Ended Cable Option，但是你不用管他，直接測試就好！

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.

當你使用這個方法測試的時候，你就有能力看到這個距離（你的網線還剩多少米），也可以看到這個近端串擾（NEXT）和回波損耗（RL）的值。當你使用單端測試的時候，有些事情，你需要考慮，你不能測試這個插入損耗和遠端串擾。而且由於阻抗在無端連接的情況下在技術上是無限的，因此您也不會獲得非常好的回波損耗。但是如果你的線纜NEXT和RL都失敗的，你的線材可能是真的有問題。