Patent ID: 7019533

Claim:
A physical layer device that communicates over a cable, comprising: a cable tester that determines a cable status, which includes an open status, a short status and a normal status, wherein said cable tester includes: a pretest module that senses activity on said cable and selectively enables testing based on said sensed activity; a test module that is enabled by said pretest module, that transmits a test pulse on the cable, that measures a reflection amplitude, that calculates a cable length, and that determines said cable status based on said measured amplitude and said calculated cable length; a first digital signal processor (DSP) that communicates with a first pair of the cable and that includes a first echo canceller and a first finite impulse response filter with first taps; and a second DSP that communicates with a second pair of the cable and that includes a second echo canceller and a second finite impulse response filter with second taps, wherein at least one of said physical layer device and said cable tester estimates skew between said first and second pairs based on values of said first and second taps.