Communications: directive radio wave systems and devices (e.g. – Directive – Beacon or receiver
Reexamination Certificate
2001-12-18
2004-06-01
Tarcza, Thomas H. (Department: 3662)
Communications: directive radio wave systems and devices (e.g.,
Directive
Beacon or receiver
C342S357490, C342S357490
Reexamination Certificate
active
06744406
ABSTRACT:
TECHNICAL FIELD
This invention relates generally to a method and apparatus for predicting future coverage of GPS satellites and, more particularly, to a method and apparatus for determining optimal placements of pseudolites as a function of predicted future coverage of GPS satellites.
BACKGROUND
Global Positioning Satellite (GPS) systems are used extensively in tracking and monitoring the locations of a wide variety of moving objects. For example, open pit mining operations commonly use GPS to track the locations and movements of various earthworking machines, and mobile machines which provide support functions, e.g., servicing, transportation, and the like. In such mining operations, machines such as excavators, wheel loaders, track-type tractors, and the like, perform earthworking tasks such as digging, loading, leveling, and such. Other machines, such as off-road mining trucks, perform other tasks such as hauling. The complex interactions of these machines has resulted in a great need to track and monitor their activities, and GPS has become increasingly depended upon to perform this monitoring.
It is widely known that GPS involves the use of a number of satellites which orbit the earth in known, non-geosynchronous orbits. For example, the system used by the United States, i.e., NAVSTAR, uses twenty-four (24) satellites, which are spaced apart in various orbits. For many applications, at least three (3), and preferably at least four (4), satellites are in line-of-sight view by a GPS antenna and receiver located on the surface of the planet, thus providing the GPS receiver with the needed data for position determination.
However, situations exist in which some GPS satellites are obscured from view, thus not allowing the minimum number of satellites to be used. In these situations, GPS systems cannot function as desired, and position determination may not be possible. For example, in the open pit mining operation noted above, the rugged terrain, e.g., cliff faces, deep pit areas, and the like, may obscure satellites from view and prevent GPS from being used effectively.
A technique which has been developed to counter the above situation is to place false GPS satellites, known as pseudolites, at strategic earth-bound locations to compensate for the lack of true GPS satellite information. These pseudolites function in the same manner as true GPS satellites, providing a signal similar to GPS signals to further enable position determination. Typically, the pseudolites are placed in areas in which problems with GPS coverage have been known to occur, and thus are used to overcome a situation which has already been determined to exist.
Currently, there are no known means disclosed in the art which take advantage of the ability to predict the future location of GPS satellites to determine future GPS coverage over an area at a site based on terrain data, and subsequently provide a means to compensate for inadequacies in GPS coverage prior to problems actually occurring.
The present invention is directed to overcoming one or more of the problems as set forth above.
SUMMARY OF THE INVENTION
In one aspect of the present invention a method for determining a desired position of a pseudolite at a site is disclosed. The method includes the steps of predicting an area of coverage of the site by at least one GPS satellite, determining a condition of reduced coverage as a function of the predicted area of coverage, displaying the area having reduced coverage on a terrain map, and placing a pseudolite at a location at the site to provide coverage in the area having reduced coverage.
In another aspect of the present invention a method for determining a desired position of a pseudolite at a site is disclosed. The method includes the steps of predicting an area of coverage of the site by a plurality of GPS satellites, determining a condition of reduced coverage as a function of the predicted area of coverage, displaying the area having reduced coverage on a terrain map, placing a pseudolite model on the terrain map at a desired location, displaying an area of coverage of the pseudolite model on the terrain map, and displaying a change in coverage of the area having reduced coverage as a function of the area of coverage of the pseudolite model.
In yet another aspect of the present invention a computer-based method for determining a desired position of a pseudolite at a site is disclosed. The method includes the steps of predicting areas of coverage of the site by a plurality of GPS satellites, determining a condition of at least one area at the site having reduced coverage as a function of the predicted areas of coverage, displaying the areas on a terrain map, the displayed areas indicating a level of coverage, determining an optimal location of at least one pseudolite model as a function of reduced coverage of the at least one area, displaying the at least one pseudolite model at the optimal location on the terrain map, and updating the terrain map display to indicate revised coverage in the areas as a function of the coverage of the GPS satellites and the at least one pseudolite model.
In yet another aspect of the present invention an apparatus for determining a desired position of a pseudolite at a site is disclosed. The apparatus includes at least one mobile machine located at the site, a GPS receiver located on the mobile machine for receiving signals from a plurality of GPS satellites, a display for indicating a terrain map of the site, and a processor. The processor is adapted to predict a future area of coverage of the site by the plurality of GPS satellites, determine a condition of predicted reduced coverage in at least one area of the site, and provide information to the display to indicate the at least one area having reduced coverage, the area having reduced coverage being indicative of a desired position of a pseudolite at the site.
REFERENCES:
patent: 5375059 (1994-12-01), Kyrtsos et al.
patent: 5430657 (1995-07-01), Kyrtsos
patent: 6188353 (2001-02-01), Mitchell
patent: 6201497 (2001-03-01), Snyder et al.
The use of pseudo-satellites for improving GPS performance, D. Klein et al., Navigation: Journal of the Institute of Navigation, vol. 31(4), Winter 1984-1985.*
Precise positioning with GPS near obstructions by augmentation with pseudolitees, J.M. Stone et al., IEEE Position Location an Navigation Symposium, Apr. 20-23, 1998.*
Integration of GNSS and Pseudo-Satellites: New Concepts for Precise Positioning, J. Wang et al., IAG Scientific Assembly, Sep. 2-7, 2001.*
Pseusolite-based inverted positioning and its applications, L. Dai et al., 5th Int. Symp. on Satellite Navigation Technology & Applications, Jul. 24-27, 2001.*
Optimal locations of pseudolites for differential GPS, B.W. Parkinson et al., Navigation: Journal of the Institute of Navigation, vol. 33(4), Winter 1986-1987.*
GPS Pseudolites: Theory, Design, and Applications, H.S. Cobb, Ph.D. Thesis, Dept. of Aeronautics and Astronautics, Stanford University, p. 28-37, 124-126, Sep. 1997.
Allen William E.
Kalafut James J.
Caterpillar Inc
Fahlberg Robin S
Lundquist Steve D
Mull Fred H
Tarcza Thomas H.
LandOfFree
Determining desired pseudolite locations based on predicted... does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Determining desired pseudolite locations based on predicted..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Determining desired pseudolite locations based on predicted... will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-3339126