Electricity: measuring and testing – Of geophysical surface or subsurface in situ – For small object detection or location
Patent
1983-04-11
1987-01-27
Karlsen, Ernest F.
Electricity: measuring and testing
Of geophysical surface or subsurface in situ
For small object detection or location
324 67, G01R 1900, G01V 308, G01V 310
Patent
active
046396748
ABSTRACT:
In locating current-carrying objects, such as buried pipes in the presence of extraneous magnetic fields by detecting the magnetic field produced by the current, first and second spaced primary sensors measure the magnetic field at first and second locations, and a compensating sensor measures the extraneous field at a location midway between the first and second locations. The signal from the compensating sensor is combined with the signals from both of the primary sensors so as to compensate for the extraneous magnetic field at the primary sensors. The invention compensates for ambient magnetic fields associated with propagating electromagnetic energy that induces current in an object, and compensates for extraneous magnetic fields produced by current flow in an adjacent object.
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"Model Mac-5113 Magnetic and Cable Locator" instruction manual, May 1985.
Karlsen Ernest F.
Schonstedt Instrument Company
Snow Walter E.
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