GPS accumulated delta range processing for navigation applications
First Claim
1. A method of determining navigational parameters of a moving object, comprising:
- making pseudorange (PR) measurements at the object from signals received from ranging signal sources;
making accumulated delta range (ADR) measurements at the object from signals received from the ranging signal sources;
computing ADR differences between ADR measurements separated by a time interval that is greater than a time interval between consecutive ADR measurements;
determining an optimal time interval between ADR measurements to be used for computing the ADR differences; and
estimating at least one navigation parameter of the moving object from the PR measurements and the ADR differences.
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Accused Products
Abstract
Techniques for GPS navigation used to determine the position and velocity of a moving object. Pseudorange (PR) measurements and accumulated delta range (ADR) measurements are made at the object from received GPS signals. Differences are computed between ADR measurements that are separated by a time interval that is greater than a time interval between consecutive ADR measurements. Navigational parameters (e.g., position, velocity and clock) are estimated from the PR measurements and the ADR differences. The ADR measurement equations set for herein are formulated in a much more accurate way so that the time interval between the ADR measurements used to compute an ADR difference can be much larger than that used for current ADR differencing techniques in GPS navigation applications. Consequently, the ADR differences are more accurate, which translates into a much more accurate navigation solution. In addition, the ADR differencing technique contributes to shorten convergence times of the Kalman filter processing, and thereby improve the accuracy of spacecraft navigation. Techniques are also provided to extend these highly accurate ADR processing algorithms to integrated GPS/IMU navigation applications, where IMU data is used as an accurate propagation model to propagate the state vector.
35 Citations
47 Claims
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1. A method of determining navigational parameters of a moving object, comprising:
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making pseudorange (PR) measurements at the object from signals received from ranging signal sources; making accumulated delta range (ADR) measurements at the object from signals received from the ranging signal sources; computing ADR differences between ADR measurements separated by a time interval that is greater than a time interval between consecutive ADR measurements; determining an optimal time interval between ADR measurements to be used for computing the ADR differences; and estimating at least one navigation parameter of the moving object from the PR measurements and the ADR differences. - View Dependent Claims (2, 3, 4, 5, 6, 7)
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8. A method of determining navigational parameters of a moving object, comprising:
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making pseudorange (PR) measurements at the object from signals received from ranging signal sources; making accumulated delta range (ADR) measurements at the object from signals received from the ranging signal sources; computing ADR differences between ADR measurements separated by a time interval that is greater than a time interval between consecutive ADR measurements; estimating at least one navigation parameter of the moving object from the PR measurements and the ADR differences, wherein estimating comprises computing partial derivatives of the ADR differences with respect to at least a velocity component of a state vector that represents position and velocity of the object to derive instantaneous velocity estimates of the object and propagating the state vector with propagation equations that compute the state vector for the object at time N based on the state vector at time N−
1. - View Dependent Claims (9, 10, 11, 12, 13, 14, 15)
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16. A method of determining navigational parameters of a moving object, comprising:
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making pseudorange (PR) measurements at the object from signals received from ranging signal sources; making accumulated delta range (ADR) measurements at the object from signals received from the ranging signal sources; computing ADR differences between ADR measurements at two epochs separated by a time interval which is greater than a time period between consecutive epochs at which ADR measurements are made; estimating at least one navigation parameter of the moving object from the PR measurements and the ADR differences. - View Dependent Claims (17)
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18. A method of determining navigational parameters of a moving object, comprising:
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making pseudorange (PR) measurements at the object from signals received from ranging signal sources; making accumulated delta range (ADR) measurements at the object from signals received from the ranging signal sources; computing ADR differences between ADR measurements separated by a time interval that is greater than a time interval between consecutive ADR measurements; estimating at least one navigation parameter of the moving object from the PR measurements and the ADR differences, wherein estimating further comprises propagating a state vector based on inertial measurement data produced by an inertial measurement unit (IMU) associated with said object. - View Dependent Claims (19, 20, 21, 22, 23, 24, 25)
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26. A method for determining the position and velocity of a moving object, comprising:
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making pseudorange (PR) measurements at the object from signals received from ranging signal sources; making accumulated delta range (ADR) measurements at the object from signals received from the ranging signal sources; computing ADR differences between ADR measurements separated by a time interval that is greater than a time interval between consecutive ADR measurements; and estimating components of a state vector comprising at least position and velocity of the object at a current state from the PR measurements and the ADR differences and the state vector at a prior state, wherein estimating comprises computing partial derivatives of the ADR differences with respect to at least a velocity component of the state vector to derive instantaneous velocity estimates of the object. - View Dependent Claims (27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43)
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44. A processor readable medium storing instructions that, when executed by a processor, cause the processor to:
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obtain pseudorange (PR) measurements at the object from signals received from ranging signal sources; obtain accumulated delta range (ADR) measurements at the object from signals received from the ranging signal sources; compute ADR differences between ADR measurements separated by a time interval that is greater than a time interval between consecutive ADR measurements; and estimate at least one navigational parameter of the moving object from the PR measurements and the ADR differences by applying a mathematical formulation that maps the ADR differences to a current state vector of the object, wherein the state vector comprises at least position and velocity of the object. - View Dependent Claims (45, 46)
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47. A method of determining navigational parameters of a moving object, comprising:
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making pseudorange (PR) measurements at the object from signals received from ranging signal sources, wherein making ADR measurements comprises making ADR measurements of the object while it has a non-constant velocity between consecutive ADR measurements; making accumulated delta range (ADR) measurements at the object from signals received from the ranging signal sources; computing ADR differences between ADR measurements separated by a time interval that is greater than a time interval between consecutive ADR measurements; and estimating at least one navigation parameter of the moving object from the PR measurements and the ADR differences.
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Specification