9.7 Range of Equipment for Testing Structured Cabling Projects
9.7.10 Causes of near-end crosstalk
Several factors can contribute to near-end crosstalk. The most common cause is crossed pairs. As mentioned earlier, you can detect these with the wire map feature of a cable tester. Near-end crosstalk can also be caused by twisted pairs that have become untwisted after being attached to cross-connect devices (e.g. patch panels) that have patch cords that are untwisted, or by cables that have been pulled too tightly around sharp corners, causing pairs to change position inside the cable jacket.

If you measure near-end crosstalk, you should do a visual check of the horizontal cabling, in order to rule out any of these possibilities. If you find nothing, then split pairs have most likely caused the problem. A cable tester measures for near-end crosstalk by measuring a series of frequencies up to 100 MHz. High numbers are good; low numbers indicate problems on the network.

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