Distinguishing false signals in cable locating
AssigneeMerlin Technology, Inc.
InventorsJohn E. Mercer, Albert W. Chau
Life of this patent
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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.
Claims16
A cable locating system for use 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, said system comprising:
- a transmitter for generating said locating signal frequency for coupling onto the first cable and for transmitting a reference signal, which includes said locating signal frequency modulated thereon;
- and
- a receiver configured to distinguish the locating signal from the false locating signal based on a modulation envelope of the reference signal as compared to the locating signal and the false locating signal.
Dependencies are inferred from the claim text.