What is Far-End Crosstalk (FEXT) a measurement of?

Far-End Crosstalk (FEXT) specifically refers to the interference that occurs in a multi-pair cable due to signals in one pair affecting signals in another pair at the far end of the cable, rather than the near end or the output. In essence, it is a measurement of how much crosstalk (which is unwanted noise or signal interference) is induced in one channel of communication due to the operation of adjacent channels, with the measurement being taken at the far end of the cable. This type of interference can significantly impact the quality and integrity of the signal being transmitted.

Crosstalk is especially relevant in telecommunications, where multiple wires are bundled together. FEXT emphasizes the importance of managing crosstalk effects for maintaining effective communication over distances. Understanding FEXT is vital for engineers to ensure strong signal integrity and minimize transmission errors, particularly in high-frequency or high-capacity networks. Thus, its recognition is imperative when evaluating cable performance in communication systems.