Communications: directive radio wave systems and devices (e.g. – Directive – Including a satellite
Reexamination Certificate
1998-10-16
2001-05-08
Blum, Theodore M. (Department: 3662)
Communications: directive radio wave systems and devices (e.g.,
Directive
Including a satellite
C342S357490, C342S352000
Reexamination Certificate
active
06229477
ABSTRACT:
TECHNICAL FIELD
This invention relates to methods and systems for determining a position of a communication satellite utilizing two-way ranging through multiple transceivers.
BACKGROUND ART
Current Automatic Dependent Surveillance (ADS) technology, such as Global Positioning System (GPS), Wide Area Augmentation System (WAAS) or GLONASS, provides positioning information utilizing satellite transmissions. For example, the GPS, developed and deployed by the U.S. Department of Defense, consists of 24 satellites orbiting the earth twice a day at an altitude of 12,000 miles, as well as five ground stations to monitor and manage the satellite constellation. Using atomic clocks and location data, GPS satellites transmit continuous time and position information 24 hours a day to a GPS receiver, which listens to four or more satellites at once to determine a user's position. By measuring the time interval between the transmission and the reception of a satellite signal, the GPS receiver calculates the distance between the user and each satellite, and then uses the distance measurements of at least four satellites to arrive at a position.
Such systems, however, utilize one-way ranging in which an accurate, synchronized clock is required at each station. Any synchronization error or error regarding the location of one of the satellites results in an error in the determined position of the target vehicle.
Any type of satellite based navigation system must determine the position and velocity of its ranging satellites to extremely high accuracy. Position and velocity determination are vital parts of the station-keeping function for any satellite, even one which is not part of a navigation system.
One known system requires the satellite to have simultaneous contact with all of its ground stations in order to obtain position information. This, however, may not always be possible for a satellite in a non-geostationary orbit which moves relative to the Earth and, therefore, periodically loses access to any given point on the Earth's surface.
DISCLOSURE OF THE INVENTION
It is thus a general object of the present invention to provide a method and system for determining the position of a communication satellite utilizing two-way ranging.
In carrying out the above object and other objects, features, and advantages of the present invention, a method is provided for determining a position of an orbiting transceiver in a communications network including at least a first and second transceiver at a first and second known location, respectively, on Earth. The first and second transceivers are adapted to transmit and receive communications signals to and from the orbiting transceiver. The method includes determining a first and second range measurement between each of the first and second transceivers and the orbiting transceiver, respectively. The method further includes determining a first and second range rate corresponding to a time rate of change of the first and second range measurements, respectively. The method also includes determining a circle of intersection representative of the set of possible positions for the orbiting transceiver based on the first range and the first range rate wherein the circle of intersection includes a specific orientation in space, a specific radius and a center in a specific, three dimensional position relative to the known position of the first transceiver. Still further, the method includes determining an angular position of the orbiting transceiver along the circle of intersection based on the known position of the second transceiver and the second range measurement. Finally, the method includes determining the position of the orbiting transceiver based on the circle of intersection and the angular position.
In further carrying out the above object and other objects, features, and advantages of the present invention, a system is also provided for carrying out the steps of the above described method. The system includes at least a first and second transceiver at a first and second known location, respectively, on Earth. The first and second transceivers are adapted to transmit and receive communications signals to and from the orbiting transceiver. A processor coupled to one of the first and second transceivers is operative to determine a first and second range measurement between each of the first and second transceivers and the orbiting transceiver, respectively. The processor is further operative to determine a first and second range rate corresponding to a time rate of change of the first and second range measurements, respectively. Still further, the processor is operative to determine a circle of intersection representative of the set of possible positions for the orbiting transceiver based on the first range measurement and the first range rate wherein the circle of intersection includes a specific orientation in space, a specific radius, and a center in a specific, three-dimensional position relative to the known position of the first transceiver. The processor further determines an angular position of the orbiting transceiver along the circle of intersection based on the known position of the second transceiver and the second range measurement. Finally, the processor determines the position of the orbiting transceiver based on the circle of intersection and the angular position.
REFERENCES:
patent: 5739785 (1998-04-01), Allison et al.
patent: 5920284 (1999-07-01), Victor
patent: 5944770 (1999-08-01), Enge et al.
patent: 5945948 (1999-08-01), Bufford et al.
patent: 2 271 902A (1993-10-01), None
patent: 2 306 827A (1997-05-01), None
patent: 2-28580 (1990-01-01), None
patent: 3-291584 (1991-12-01), None
patent: 4-27887 (1992-01-01), None
patent: 7-146995A (1995-06-01), None
patent: 9-026328 (1997-01-01), None
patent: 9-113600A (1997-05-01), None
patent: 1-0090391A (1998-04-01), None
Chang Donald C. D.
Cheng David C.
Nunan William J.
Shuman Bruce E.
Yung Kar W.
Blum Theodore M.
Duraiswamy V. D.
Hughes Electronics Corporation
Sales M. W.
LandOfFree
Method and system for determining a position of a... does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Method and system for determining a position of a..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Method and system for determining a position of a... will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2500602