Geophysics-based method of locating a stationary earth object
First Claim
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1. A geophysics-based method for fixing a position of a stationary earth object, comprising:
- a) providing a model that predicts tidal acceleration at a plurality of locations on the earth as a function of time and location relative to a reference time in an earth-fixed frame comprising orthogonal axes,b) measuring an acceleration in at least one direction of the stationary earth object at an actual location for a period of time relative to the reference time with a sensor package in a sensor frame comprising orthogonal axes,c) transforming the sensor frame using an estimated rotation matrix,d) estimating a position of the object to input to the model to provide a predicted acceleration at the estimated position,e) comparing the measured acceleration in the transformed frame to the predicted acceleration in the earth-fixed frame with a pattern recognition algorithm to provide a goodness-of-fit metric for the estimated position, andf) repeating steps b) to e) at least once to provide the position fix for the actual location of the stationary earth object.
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Abstract
A geophysics-based method for determining the position of a stationary earth object uses the periodic changes in the gravity vector of the earth caused by the sun- and moon-orbits. Because the local gravity field is highly irregular over a global scale, a model of local tidal accelerations can be compared to actual accelerometer measurements to determine the latitude and longitude of the stationary object.
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24 Claims
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1. A geophysics-based method for fixing a position of a stationary earth object, comprising:
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a) providing a model that predicts tidal acceleration at a plurality of locations on the earth as a function of time and location relative to a reference time in an earth-fixed frame comprising orthogonal axes, b) measuring an acceleration in at least one direction of the stationary earth object at an actual location for a period of time relative to the reference time with a sensor package in a sensor frame comprising orthogonal axes, c) transforming the sensor frame using an estimated rotation matrix, d) estimating a position of the object to input to the model to provide a predicted acceleration at the estimated position, e) comparing the measured acceleration in the transformed frame to the predicted acceleration in the earth-fixed frame with a pattern recognition algorithm to provide a goodness-of-fit metric for the estimated position, and f) repeating steps b) to e) at least once to provide the position fix for the actual location of the stationary earth object. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24)
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