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Propagation Delay and Delay Skew

Propagation delay and delay skew requirements for all compliant 4-pair 100 Ohm cables have been added for testing category 5e cable. Propagation delay and delay skew requirements of multipair cables are subject to additional study.

Propagation delay is equivalent to the amount of time that passes between when a signal is transmitted and when it is received at the other end of a cabling channel. Delay skew is the difference between the pair with the least delay and the pair with the most delay. Transmission errors that are associated with excessive delay and delay skew include increased jitter and bit error rates.

The maximum propagation delay skew requirement for 4-pair 100 Ohm cables is frequency dependent and is specified by the following equation:

Cable delay skew shall not exceed 45 ns/100m between 1 MHz and the highest referenced frequency for a given category.

The requirements of propagation delay and delay skew are also applicable to category 6 cable specifications while more stringent performance criteria are specified for category 7 cables.