Method and apparatus employing received independent magnetic field components of a transmitted alternating magnetic field for determining location
US4710708A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Jul 23, 1982 |
| Grant date | Dec 1, 1987 |
| Priority date | — |
| Expiry date | Jul 23, 2002 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG01V3/08
- WIPO fieldMeasurement
- WIPO sectorInstruments
Abstract
The location method uses relatively low frequency electromagnetic fields, e.g., 1-1000 Hz, for determining the relative position and/or orientation of a transmitting magnetic dipole antenna by using a vector field receiver. The transmitting antenna for subterranean location, is preferably a single axis, elongated solenoid with a ferromagnetic core. The receiving sensor may be a precise three-axis magnetic field detector of either a magnetometer or search coil type. Measurements are made for one or more positions of either the transmitter or receiver, or with one or more transmitters or receivers. The relative location of the transmitter and the receiver is calculated with respect to some known survey station by a method of successive approximations. The operating frequency is chosen to minimize field distortion from common steel structures, such as pipe, casing or railroad tracks, and to minimize field scattering such as from conducting inhomogeneities in the earth. Either the transmitter or receiver can be operated within metal structures such as casing. The method can be used for location of underground boreholes or pipelines; location of trapped miners; as a means of blind surve…
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.