Cable detection apparatus and method

摘要

A cable detection apparatus comprises a detector (810), and a filter (820) arranged to filter an output from the detector, the filter increasing the relative strength of signal components at a plurality of harmonics of a first frequency to at least one non-harmonic frequency between two of said harmonics of the first frequency. Thus the filter provides lower attenuation at the plurality of harmonics of the first frequency than at non-harmonics. The apparatus also includes an oscillator (840) for frequency shifting the filtered signal to frequency shift the high relative strength frequencies of the filter to coincide with reduced relative strength frequencies of the filtered signal. The shifted signal is fed to a loudspeaker (860) for audible indication of cable location. The apparatus may also filter out even harmonics of the signal whilst passing odd harmonics.