Cable tester with insertion loss and return loss estimators

摘要

A physical layer device that communicates over a cable comprises a cable tester that determines a cable status, which includes an open status, a short status, and a normal status. The cable tester includes a pretest module that senses activity on the cable and selectively enables testing based on the sensed activity. A test module is enabled by the pretest module, transmits a test pulse on the cable, measures a reflection amplitude, calculates a cable length, and determines the cable status based on the measured amplitude and the calculated cable length. An insertion loss estimator communicates with the cable tester and estimates insertion loss of the cable. A return loss estimator communicates with the cable tester and estimates return loss of the cable based on gain parameters of the physical layer device.