Before you press TEST, it helps to know what you are actually measuring. Four things that come back in every measurement: twisted-pair construction, shielding, link topology, and the difference between category and class.
A twisted-pair cable is 8 copper conductors in 4 pairs. Current flowing in a conductor creates an electromagnetic field that interferes with neighboring conductors — twisting the pair makes the opposing fields cancel each other out. The tighter and more uniform the twist, the higher the achievable transmission speed.
The cable must be terminated to the same wiring scheme at both ends — T568A or T568B. Mixing the schemes at the two ends = crossed pairs in the wire map.
The designation before the slash describes the overall cable screen, after the slash — the screening of the individual pairs:
| Designation | Overall screen | Pair screen | In practice |
|---|---|---|---|
| U/UTP | none | none | Classic unshielded twisted pair. The cheapest, sensitive to EMI. |
| F/UTP | aluminum foil | none | Commonly called "FTP". A popular compromise between price and immunity. |
| U/FTP | none | each pair in foil | Good NEXT without an outer screen. A frequent choice for Cat 6A. |
| S/FTP | braid | each pair in foil | The best EMI protection — the standard in industrial Cat 6A/7 installations. |
| SF/UTP | foil + braid | none | An older construction known as "STP". |
Shielding has its own measurement thread: screen continuity along the entire link and its grounding are verified by the TCL/ELTCL parameters (module 2), and foil nicked while terminating a jack is a classic cause of a NEXT FAIL (module 5).
The ISO/EN names keep coming back in design documentation and in limit names, so they are worth knowing:
The daily bread of certification is the horizontal cabling FD → TO — and it is exactly this run that the Permanent Link / Channel / MPTL link models describe, which you will set up in the tester (module 3).
Category describes the performance of components: the cable on the reel, the patch cord, the keystone jack, the panel. Class describes the performance of the entire assembled link — and it is the class (the link) that your tester measures and certifies. A weak Cat 5e jack on excellent Cat 6A cable drags down the result of the whole link: the weakest component determines the link class.
| Frequency | Category (components) | Class (link) | Application |
|---|---|---|---|
| 100 MHz | Cat 5e | D | 1 Gbit — 100 m |
| 250 MHz | Cat 6 | E | 1 Gbit — 100 m |
| 500 MHz | Cat 6A | EA | 10 Gbit — 100 m ★ the scope of this course |
| 600 MHz | Cat 7 | F | 10 Gbit — 100 m |
| 1000 MHz | Cat 7A | FA | 10 Gbit — 100 m / 40 Gbit — 30 m |
| 2000 MHz | Cat 8.1 | I | 40 Gbit — 30 m (data center) |
The category naming comes from the TIA world (USA), the classes — from ISO/IEC and EN. In the field you will hear both: "Cat 6A certification" and "Class EA link" describe the same level of requirements, just from the perspective of two families of standards. Which standard to select in the tester — that comes in module 3, with the limit wizard.
You have the fundamentals. Next step: what exactly the autotest measures and how to read each of the tester's screens.