Patent ID: 7415367

Claim:
An apparatus for locating an actual source of CPD in a two-way cable system having downstream and upstream frequency bands, the cable system containing a downstream signal which propagates in the downstream frequency band, and the downstream signal containing a plurality of TV channel carriers, said apparatus comprising: a local CPD source including an input for receiving a sample of the downstream signal from a point in the cable system, said local CPD source further including a distortion generator configured to generate a local distortion signal from the sample of the downstream signal, the actual source of GPO mixing the TV channel carriers of the downstream signal to create an upstream actual distortion signal which propagates in the upstream frequency band of the cable system; a cross-correlator adapted to perform a cross-correlation between the local distortion signal and the upstream actual distortion signal, said cross-correlator being coupled to said local CPD source to receive the local distortion signal and having an input for receiving the upstream actual distortion signal; and means for determining a time delay between the local distortion signal and the upstream actual distortion signal from the cross-correlation of said cross-correlator, wherein a round-trip time between the point and the actual source of CPD is determined from the time-delay.