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US 6,724,192 B1Granted
Method and apparatus for exploration using GMR sensors
AssigneeT. David McGlone
InventorT. David McGlone
Life of this patent
Estimating the term…
Abstract
An instrument for geophysical measurement of magnetic field strength, using a GMR sensor is provided. The instrument achieves high sensitivity across a relatively wide bandwidth in an instrument which is small and lightweight. The instrument makes it feasible to obtain data, substantially simultaneously, at a plurality of locations and/or frequencies, thus not only reducing time requirements involved in measurements but reducing or eliminating the need for correcting data for changes in earth's magnetic fields. The instrument has relatively high vector sensitivity and relatively low power consumption.
Claims53
An exploration instrument comprising:
- a GMR sensor;
- an excitation circuit coupled to said sensor, wherein said excitation circuit supplies a DC voltage to said GMR sensor;
- and
- a signal combiner coupled to said GMR sensor, wherein said signal combiner removes an ambient planetary magnetic field component from a GMR output signal and wherein said sensor has a bandwidth with an effective upper limit greater than about 50 MHZ.
1 more element
An exploration instrument comprising:
- a GMR sensor having at least a first output means;
- means for providing a conditioned DC excitation signal to said sensor;
- means for removing from an output signal outputted by said first output means a component that is proportional to an ambient magnetic field to form an adjusted signal;
- means for amplifying said adjusted signal;
- and
- means for filtering said adjusted signal.
3 more elements
A system for detecting magnetic fields adjacent a target region, comprising:
- a plurality of detectors, each detector having at least one GMR sensor coupled to an excitation circuit, said detectors positioned at spaced-apart locations on or below the surface adjacent to the target region;
- and
- communication links conveying output from said detectors to a data collection device, wherein said output is proportional to a perturbation in a magnetic field strength.
A system for detecting magnetic fields adjacent a target region, comprising:
- a plurality of detectors, each detector having at least one GMR sensor coupled to an excitation circuit, said detectors positioned at spaced-apart locations adjacent to a target region, each said detector having a mass of less than about 0.5 kg;
- communication links conveying output from said detectors to a data collection device;
- said detectors operating above about 80° K, providing a sensitivity of better than about ±10 microOersted and a bandwidth from substantially DC to about 4 MHZ and having sufficient vector sensitivity to provide a rejection of at least about 30 dB, wherein said output is proportional to a perturbation in a measured magnetic field.
An exploration method, comprising:
- providing at least a first GMR sensor;
- locating said first sensor at a first location;
- and
- measuring a perturbation in magnetic field strength at said first location using said first sensor, indicative of a geophysical characteristic of a selected region through which said magnetic field passes.
1 more element
A method for measuring a magnetic field, comprising:
- providing a plurality of GMR sensors;
- locating said plurality of sensors at a plurality of locations;
- measuring a magnetic field strength at said plurality of locations, substantially simultaneously, using said plurality of sensors;
- and
- removing an ambient magnetic field strength from the measured magnetic field strengths.
2 more elements
A method for measuring a magnetic field, comprising:
- providing a plurality of detectors, each detector having at least one GMR sensor coupled to an excitation circuit, each said detector having a mass of less than about 0.5 kg;
- said detectors operating above about 80° K, providing a sensitivity of better than about ±10 microOersted and a bandwidth from substantially DC to about 4 MHZ and having sufficient vector sensitivity to provide a rejection of at least about 30 dB;
- locating said plurality of sensors at a plurality of locations on or below a celestial body's surface;
- measuring a magnetic field strength at said plurality of locations, substantially simultaneously, using said plurality of sensors;
- and
- adjusting the measured magnetic field strength to provide a perturbation in magnetic field strength relative to an ambient magnetic field strength.
3 more elements
An exploration instrument comprising:
- a GMR sensor providing a GMR output;
- an excitation circuit coupled to said sensor, wherein said excitation circuit supplies a DC voltage to said GMR sensor, wherein the GMR output is a substantially linearly responsive signal.
A method for measuring a magnetic field, comprising:
- providing at least a first GMR sensor;
- measuring a magnetic field strength, substantially simultaneously, using said at least a first GMR sensor;
- and
- providing a substantially linearly responsive output signal from the at least a first GMR sensor.
1 more element
An exploration instrument comprising:
- a GMR sensor;
- an excitation circuit coupled to said sensor, wherein said excitation circuit supplies a DC voltage to said GMR sensor;
- and
- a signal combiner coupled to said GMR sensor, wherein said signal combiner removes an ambient magnetic field component from a GMR output signal and wherein said GMR has a sensitivity and said sensitivity is better than about ±2 microOersted.
1 more element
An exploration instrument comprising:
- a GMR sensor;
- an excitation circuit coupled to said sensor, wherein said excitation circuit supplies a DC voltage to said GMR sensor;
- and
- a signal combiner coupled to said GMR sensor, wherein said signal combiner removes an ambient magnetic field component from a GMR output signal and wherein said sensor has a mass of less than about 500 grams.
1 more element
An exploration instrument comprising:
- a GMR sensor;
- an excitation circuit coupled to said sensor, wherein said excitation circuit supplies a DC voltage to said GMR sensor;
- and
- a signal combiner coupled to said GMR sensor, wherein said signal combiner removes an ambient magnetic field component from a GMR output signal and wherein said sensor occupies a volume of less about 300 cm3.
1 more element
An exploration instrument comprising:
- a GMR sensor;
- an excitation circuit coupled to said sensor, wherein said excitation circuit supplies a DC voltage to said GMR sensor;
- and
- a signal combiner coupled to said GMR sensor, wherein said signal combiner removes an ambient magnetic field component from a GMR output signal and wherein the GMR sensor provides a GMR output, and wherein the GMR output is substantially linearly responsive.
1 more element
An exploration instrument comprising:
- a GMR sensor;
- an excitation circuit coupled to said sensor, wherein said excitation circuit supplies a DC voltage to said GMR sensor;
- and
- a signal combiner coupled to said GMR sensor, wherein said signal combiner removes an ambient magnetic field component from a GMR output signal and wherein said sensor has a bandwidth with an effective upper limit greater than about 4 MHZ.
1 more element
An exploration instrument comprising:
- a GMR sensor;
- an excitation circuit coupled to said sensor, wherein said excitation circuit supplies a DC voltage to said GMR sensor;
- and
- a signal combiner coupled to said GMR sensor, wherein said signal combiner removes an ambient magnetic field component from a GMR output signal and wherein said sensor has a bandwidth with a lower range extending substantially to DC.
1 more element
An exploration instrument comprising:
- a GMR sensor;
- an excitation circuit coupled to said sensor, wherein said excitation circuit supplies a DC voltage to said GMR sensor and comprises a filter for providing a substantially noise-free excitation signal to said sensor;
- and
- a signal combiner coupled to said GMR sensor, wherein said signal combiner removes an ambient magnetic field component from a GMR output signal.
1 more element
An exploration instrument comprising:
- a GMR sensor;
- an excitation circuit coupled to said sensor, wherein said excitation circuit supplies a DC voltage to said GMR sensor;
- a signal combiner coupled to said GMR sensor, wherein said signal combiner removes an ambient magnetic field component from a GMR output signal;
- and
- means for providing anti-aliasing to an output of said sensor.
2 more elements
Dependencies are inferred from the claim text.