Data processing: vehicles – navigation – and relative location – Vehicle control – guidance – operation – or indication – Aeronautical vehicle
Reexamination Certificate
1999-01-28
2001-05-15
Zanelli, Michael J. (Department: 3661)
Data processing: vehicles, navigation, and relative location
Vehicle control, guidance, operation, or indication
Aeronautical vehicle
C701S226000
Reexamination Certificate
active
06233507
ABSTRACT:
BACKGROUND
1. The Field of the Invention
This invention relates to a system and method for determining the position of a satellite relative to time.
2. The Background Art
Satellite technology has revolutionized the modern world and provided numerous benefits to society in commerce and science. With additional advancements in technology, society's dependence on satellite technology grows. An efficient and well maintained satellite network is essential to the advancement of modern society.
A necessity of satellite technology is the ability to determine the position of a given satellite at particular times. This is critical to maintain accurate positions data on thousands of satellites in orbit. Furthermore, telecommunication and telemetry systems require precise knowledge of satellite positions in order to enable transmissions. Time-motion relationships are required in order to determine intercept or rendezvous orbits for satellites and other spacecraft.
Systems that determine a satellite's position require several parameters characterizing the satellite's orbit, including radius, eccentricity, and orbit type. Circular orbits provide uniform angular velocity. A time-position solution is a straightforward calculation. All other orbits may be defined as conic sections with non-zero values of eccentricity.
A computer program may execute a sequence of calculations to approximate the time-position relationships of satellites by incorporating a parameter called the “eccentric anomaly.” Numerical methods (e.g., the Newton-Raphson method of successive approximations) are required to converge on a solution. To determine a satellite's coordinates at any given time requires substantial computational capacity. The computational demands become overwhelming when orbital data from hundreds or thousands of satellites must be computed to ensure a safe trajectory for a satellite.
Thus, it would be an advancement in the art to provide a faster, reliable, sifficiently accurate method for determining satellite position. More efficient convergence would reduce processing time.
BRIEF SUMMARY AND OBJECTS OF THE INVENTION
An apparatus and method in accordance with the invention provides a unique system to determine an orbiting satellite's position as a function of time using hardware or software and a simplified equation set. The invention may be incorporated into a software module or apparatus to be used as part of a pointing, tracking, or navigation system. The invention may serve both ground-based and orbit-based applications.
The invention incorporates an eccentric conformance module that determines time and position for each satellite. The eccentric conformance module eliminates the necessity of computing the conventional eccentric anomaly for non-circular orbits. Calculating orbital motion based on a straightforward comparison with a circular orbit requires or relies on the application of a general power equation. This eccentric conformance method applies to variables, equations, and entire models developed to eliminate the eccentric anomaly calculations.
The eccentric conformance module produces coordinates in a reference frame relating to an eccentric conformance model. The invention resolves these coordinates through transformation to a common reference frame by computing the transformation between the conformance displacement angle and the true anomaly.
The invention uses the calculations derived from the eccentric conformance module for ground-based and space-based system applications. These applications include determination of line-of-sight pointing for antennas and predictions of satellite positions for intercept or rendezvous transfers and for safe orbit trajectories. All such computations are simplified with the use of the eccentric conformance method.
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patent: 08262119A (1996-10-01), None
Gibson Eric M
Madson & Metcalf
Zanelli Michael J.
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