Underground object locating system without direction ambiguity
US6859162B2 · kind B2 · utility
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5References
25Claims
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Key dates
| Filing date | Feb 15, 2002 |
| Grant date | Feb 22, 2005 |
| Priority date | — |
| Expiry date | Nov 27, 2022 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG01V3/12
- WIPO fieldMeasurement
- WIPO sectorInstruments
Abstract
In an underground object locating system in which a modulated RF signal is applied to the underground object and an emitted signal is detected by a receiver, ambiguity in the direction of current flow in the underground object is resolved by modulating the RF signal with a modulation signal such that the modulated signal, f(t) has an average value of zero and is not equal to −f(t+K) where K is any practical value. In specific embodiments, the modulation can be amplitude modulation where the modulating signal is lower in frequency than the RF signal and is related thereto by a rational number, such as one-half (½).
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.