Avoiding ghosting artifacts during surface location of subsurface transmitters
US5621325A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | May 16, 1995 |
| Grant date | Apr 15, 1997 |
| Priority date | — |
| Expiry date | May 16, 2015 |
Classification
- Technology area (CPC E)Fixed Constructions
- CPC primaryE21B47/0232
- WIPO fieldMeasurement
- WIPO sectorInstruments
Abstract
An apparatus and method is provided for determining if the signal received from an underground beacon (10) at a locator (22) is a true signal or a ghost signal. Orthogonal horizontal antenna (38) and vertical antenna (40) are used and a ratio is computed of the signal strengths measured by the two antennas. At the true location, the signal strength in the horizontal antenna (38) will be maximum and the signal strength of the vertical antenna (40) will be a null. If the ratio of the signal strength sensed by the horizontal antenna and vertical antenna is large, exceeding a predetermined value, the locator is receiving a valid signal from the beacon and a display of this fact is made on a display on the locator and the depth of the beacon is calculated. If the ratio is less than the predetermined value, a ghost signal is being received and this fact is displayed on the display on the locator (22).
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.