Patent ID: 8548760

Claim:
An apparatus for determining a cable length between a test point and a source of nonlinearity in a cable plant for propagating upstream and downstream signals, the apparatus comprising: a peak detector for providing a triggering signal upon detection of a downstream signal peak at the test point of the cable plant; a waveform acquisition unit coupled to the peak detector, for acquiring, upon receiving the triggering signal from the peak detector, a waveform of the upstream signal at the test point; and a processing unit coupled to the waveform acquisition unit, for averaging upstream waveforms acquired by the waveform acquisition unit upon triggering by the peak detector, to obtain an averaged waveform of the upstream signal; for detecting an upstream signal peak in the averaged waveform of the upstream signal, wherein the upstream signal peak is an average of common path distortion upstream signal peaks induced at the source of nonlinearity by downstream signal peaks detected by the peak detector; and for determining the cable length between the test point and the source of nonlinearity, from a position of the upstream signal peak in the averaged waveform of the upstream signal.