Avoiding ghosting artifacts during surface location of subsurface transmitters

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 a...

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Bibliographische Detailangaben
Hauptverfasser:	GREGORY W. DRAPER, JIAN J. JIN, FRANK S NICKEL, MICHAEL F. GARD
Format:	Patent
Sprache:	eng
Schlagworte:	DETECTING MASSES OR OBJECTS EARTH DRILLING EARTH DRILLING, e.g. DEEP DRILLING FIXED CONSTRUCTIONS GEOPHYSICS GRAVITATIONAL MEASUREMENTS MEASURING MINING OBTAINING OIL, GAS, WATER, SOLUBLE OR MELTABLE MATERIALS OR ASLURRY OF MINERALS FROM WELLS PHYSICS TESTING
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Beschreibung
Zusammenfassung:	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).