Apparatus for and methods of electromagnetic surveying of elongated underground conductors
US4220913A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | May 23, 1978 |
| Grant date | Sep 2, 1980 |
| Priority date | — |
| Expiry date | May 23, 1998 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG01V3/06
- WIPO fieldMeasurement
- WIPO sectorInstruments
Abstract
Apparatus for detecting underground conductors carrying AC, such as cables or pipelines, has two receiver coils with horizontal axes one above the other, and other coils. By making phase comparisons from a selection of these the apparatus is located directly above the conductor. Then using the two horizontal coils there is derived a signal corresponding to the depth of the conductor, which can be visually indicated. Also, this depth signal, which is continuously available as the conductor is followed, is used to modify an output from one of the coils so that as the depth varies that output remains constant provided there are no discontinuities or faults in the cable.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.