| 摘要 |
A physical layer device communicates over a cable and includes a cable tester that determines a cable status. The cable tester includes a pretest module that senses activity on the cable. A test module transmits a test pulse on the cable, measures reflection amplitude, calculates a cable length, and determines the cable status based on the measured amplitude and the calculated cable length. A first digital signal processor (DSP) communicates with a first pair of the cable and includes a first echo canceller and a first finite impulse response filter with first taps. A second DSP communicates with a second pair of the cable and includes a second echo canceller and a second finite impulse response filter with second taps. At least one of the physical layer device and the cable tester estimates skew between the first and second pairs based on values of the first and second taps.
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