Patent ID: 7788050

Claim:
A method of ranging a distance to a source of common path distortion in a two-way cable system that has a downstream signal path and an upstream signal path, said method comprising the steps of: (a) generating a fixed frequency signal for transmission in the downstream signal path of the cable system; (b) generating a first swept frequency signal, having a first swept bandwidth, for transmission in the downstream signal path of the cable system; (c) transmitting the fixed frequency signal and the first swept frequency signal in the downstream signal path of the cable system; (d) receiving a second swept frequency signal from the upstream signal path of the cable system, the second swept frequency signal having a second swept bandwidth and being created by the source of common path distortion by a mixing action of the fixed frequency signal with the first swept frequency signal, the second swept bandwidth of the second swept frequency signal being approximately equal to the first swept bandwidth of the first swept frequency signal; (e) determining a complex frequency response associated with the second swept frequency signal; (f) determining an impulse response from the complex frequency response and obtaining a time delay from the impulse response, the time delay being associated with the source of common path distortion; and (g) determining the distance to the source of common path distortion from the time delay.