Cable detection apparatus and method
First Claim
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1. A cable detection apparatus comprisinga detector to detect an electromagnetic field;
- a filter system to receive signals from the detector and output a filtered signal, the filter system comprisinga first filter having a higher transmittance at a plurality of harmonics of a first frequency than at least one non-harmonic frequency between two of said harmonics of the first frequency;
a second filter arranged in series with the first filter having higher transmittance at least one harmonic of the first frequency than at least one non-harmonic frequency of the first frequency; and
an indicator to indicate the detection of a cable based on the filtered signal.
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Abstract
A cable detection apparatus is disclosed having a filter, the filter transmitting components of a signal detected substantially at certain harmonics of a first frequency. The filter may also attenuate the signal at certain even harmonics thereof. A method of detecting and/or locating cables in the same manner is also disclosed.
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Citations
14 Claims
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1. A cable detection apparatus comprising
a detector to detect an electromagnetic field; -
a filter system to receive signals from the detector and output a filtered signal, the filter system comprising a first filter having a higher transmittance at a plurality of harmonics of a first frequency than at least one non-harmonic frequency between two of said harmonics of the first frequency; a second filter arranged in series with the first filter having higher transmittance at least one harmonic of the first frequency than at least one non-harmonic frequency of the first frequency; and an indicator to indicate the detection of a cable based on the filtered signal. - View Dependent Claims (2, 3, 4, 5, 6, 7)
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8. A cable detection apparatus comprising second filter means for transmitting components of a signal substantially at at least one harmonic of the first frequency and attenuating other frequencies;
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detecting means for detecting an electromagnetic field; first filter means for receiving signals from the detecting means, transmitting components of the signal substantially at a plurality of harmonics of a first frequency at a higher strength than components at at least one non-harmonic frequency between two of said harmonics of the first frequency, and outputting a filtered signal; and indicating means for indicating the detection of a cable based on the filtered signal. - View Dependent Claims (9, 10, 11, 12, 13, 14)
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Specification