transverse conversion loss  TCL 橫向變換損耗
transverse conversion transfer loss  TCTL 橫變換轉移損耗
TCL (Transverse Conversion Loss) – DSX CableAnalyzer TCL is one of two balance measurements found in ANSI/TIA-568-C.2, ANSI/TIA-1005 and ISO/IEC 11801:2010. The other is ELTCTL.

The measurement is made by injecting a differential mode signal (DM) into a twisted pair, then measuring the common mode signal (CM) returned on that same twisted pair. The smaller the CM signal returned, the better the TCL measurement (balance).
 
翻譯：測量是通過向雙絞線注入差模信號（DM），然后測量同一對雙絞線返回的共模信號（CM）。CM信號返回的越少，TCL參數就會越好，越平衡。

If it looks similar to a Return Loss measurement, you're right. Except a Return Loss measurement is made by injecting a DM signal into the pair and measuring the DM signal returned. Here we are measuring the CM signal returned which is TCL.

翻譯：如果你覺得它像是回波損耗的測試，那你就說對了。回波損耗測試是通過向雙絞線注入DM（差模信號）然后測試返回的DM信號，然而TCL是測試CM信號。

Field test requirements for ANSI/TIA-568-C.2 are deferred to ANSI/TIA-1152. At this time, TCL is not a field test requirement because until the DSX CableAnalyzer came along, no field test equipment vendor could perform a TCL field test. It is anticipated that other test equipment vendors will eventually offer TCL field measurements too. Field testers are normally capable of DM measurements only – the DSX CableAnalyzer is capable of both DM and CM measurements, hence its ability to measure TCL and ELTCTL.

翻譯：對于ANSI/TIA-568-C.2現場測試要求直到ANSI/TIA-1152標準。在那個時候，TCL并不是一個現場測試的要求，因為沒有現場測試設備供應商可以執行TCL現場測試，直到DSX-5000電纜認證分析儀的誕生。預計其他品牌測試設備廠家最終也將提供TCL現場測量。現場測試人員通常僅能DM測量 – 對DSX-5000電纜認證分析儀能夠既DM和CM的測量，因此其有測量TCL與ELTCTL的能力。

If you wish to add TCL and ELTCTL to your standard Category 5e, 6, 6A or Class D, E or EA test, select your test limit under the folder in DSX called Balance Measurements and look for your test limit with a suffix of (+TCL):

翻譯：如果需要對于Cat5e，Cat6，Cat 6A測試TCL和ELTCTL參數，你只需要再DSX-5000 的文件夾下面找到+TCL的后綴就可以了。

This will add ≈ 6.6 seconds to your AUTOTEST time.
TCL測試將增加6.6秒測試時間。
The suffix of (+TCL) indicates a standard ANSI/TIA or ISO/IEC test with the addition of TCL and ELTCTLmeasurements. ANSI/TIA-568-C.2 and ISO/IEC 11801:2010 only provide test limits for Channel measurements at this time. If you select a Perm. Link test limit, the TCL and ELTCTL measurements will be performed, but there will be no PASS/FAIL criteria applied. You will also see the Industrial Ethernet standards TIA 1005 with the different E1, E2 and E3 environmental TCL and ELTCTL limits.

翻譯：有（+TCL）后綴的預示著ANSI/TIA或者ISO/IEC測試有這個規格。 目前ANSI/TIA-568-C.2 and ISO/IEC 11801:2010 僅僅提供信道測試的極限值，如果選擇永久鏈路測試，TCL和ELTCTL也會被執行，但是不會有通過/失敗的標準。同樣你也會看到工業以太網標準TIA 1005 ，E1,E2,E3的標準的限制。
 
In the example below from a DSX-5000 CableAnalyzer, a Category 6A Channel was tested. With a margin of 5.4 dB (6 dB is a factor of 2), you can feel confident that this link will perform well, even in a noisy environment.
翻譯：從下面DSX-5000的例子中可以看到，Cat 6A通道測試有5.4db的余量，你就不用擔心了，因為這條鏈路表現非常好。即使在有噪音的環境下。