Distinguishing false signals in cable locating
First Claim
1. In a region which includes at least first and second in-ground cables, each of which cables includes an electrically conductive component such that, when the first cable is driven at a locating signal frequency to emit a locating signal in an electromagnetic form, the locating signal can be coupled to the second cable in a way which causes the second cable to generate a false locating signal in electromagnetic form, a method for discriminating between the locating signal and the false locating signal, said method comprising:
- transmitting a reference signal, which contains said locating signal frequency impressed thereon, in a way which provides for detection of a phase shift between the locating signal and the false locating signal; and
based on said phase shift, using a receiver, distinguishing the locating signal from the false locating signal.
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Accused Products
Abstract
Discriminating between a cable locating signal and a false cable locating signal is described. A reference signal, which contains a locating signal frequency impressed on it, is transmitted in a way which provides for detection of a phase shift between the locating signal and the false locating signal. Based on the phase shift, a receiver is used to distinguish the locating signal from the false locating signal.
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Citations
28 Claims
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1. In a region which includes at least first and second in-ground cables, each of which cables includes an electrically conductive component such that, when the first cable is driven at a locating signal frequency to emit a locating signal in an electromagnetic form, the locating signal can be coupled to the second cable in a way which causes the second cable to generate a false locating signal in electromagnetic form, a method for discriminating between the locating signal and the false locating signal, said method comprising:
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transmitting a reference signal, which contains said locating signal frequency impressed thereon, in a way which provides for detection of a phase shift between the locating signal and the false locating signal; and based on said phase shift, using a receiver, distinguishing the locating signal from the false locating signal. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14)
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15. In a region which contains at least first and second in-ground cables, each of which cables includes an electrically conductive component such that, when the first cable is driven at a locating signal frequency to emit a locating signal in an electromagnetic form, the locating signal can be coupled to the second cable in a way which causes the second cable to generate a false locating signal in electromagnetic form, an apparatus for discriminating between the locating signal and the false locating signal, said apparatus comprising:
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a transmitter for generating said locating signal frequency and for transmitting a reference signal, which contains said locating signal frequency impressed thereon, in a way which provides for detection of a phase shift between the locating signal and the false locating signal; and a receiver for using said phase shift, as detected thereby, for distinguishing the locating signal from the false locating signal. - View Dependent Claims (16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28)
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Specification