Method and apparatus for reducing interference in electrical locating of a buried cable sheathing fault

摘要

A method and an apparatus are provided to reduce or eliminate interference signals that have been additively superimposed on a useful signal for locating a cable sheathing fault of a buried electrical cable. A correction unit includes a filter, a delay device and/or a DC component estimator. The correction unit automatically determines a transient interference signal and a DC offset voltage component that have been superimposed on the useful signal as received in an input signal of the correction unit, and then subtracts these determined interference signals from the input signal to provide the interference-free or interference-suppressed useful signal as the output.

主权项

1. A signal processing apparatus for reducing interference signals that are superimposed on a useful signal for locating a cable fault on a buried electrical cable, comprising:
an apparatus input adapted to receive an input signal including interference signals superimposed on a useful signal; a first filter that has an input thereof connected to said apparatus input, and that is adapted to at least partially filter the useful signal out of the input signal to produce a filtered signal at an output of said first filter; a delay device that has an input thereof connected to said apparatus input, and that is adapted to time-delay the input signal to produce a delayed signal at an output of said delay device; a first signal combining node that has inputs respectively connected to said output of said first filter and said output of said delay device, and that is adapted to combine the filtered signal and the delayed signal so as to produce a first combined signal at an output of said first signal combining node, wherein the first combined signal at least partially includes the useful signal and at least partially omits the interference signals; a DC component estimator that comprises a median filter, and that has an input thereof connected to said output of said first signal combining node, and that is adapted to produce an estimated DC component signal at an output of said DC component estimator; and a second signal combining node that has inputs respectively connected to said output of said first signal combining node and said output of said DC component estimator, and that is adapted to combine the first combined signal and the estimated DC component signal so as to produce a second combined signal at an output of said second signal combining node.