(12) United States Patent
Yung et al.
(io) Patent No.: (45) Date of Patent:
US 7,198,230 B2 *Apr. 3, 2007
(54) METHOD AND SYSTEM FOR MAXIMIZING SATELLITE CONSTELLATION COVERAGE
(75) Inventors: Kar W. Yung, Torrance, CA (US);
Donald C. D. Chang, Thousand Oaks,
(73) Assignee: The DirecTV Group, Inc., El Segundo, CA (US)
( * ) Notice: This patent issued on a continued prosecution application filed under 37 CFR 1.53(d), and is subject to the twenty year patent term provisions of 35 U.S.C. 154 (a)(2).
Subject to any disclaimer, the term of this patent is extended or adjusted under 35 U.S.C. 154(b) by 1560 days.
(21) Appl. No.: 08/949,988
(22) Filed: Oct. 14, 1997
Prior Publication Data
US 2001/0013566 Al Aug. 16, 2001
U.S. CI 244/158.4
Field of Classification Search 244/158 R;
342/352, 353, 356; 455/427, 429, 430, 121,
455/131, 133 See application file for complete search history.
U.S. PATENT DOCUMENTS
3,243,706 A * 3/1966 Grisham
3,340,531 A * 9/1967 Kefalas et al.
3,995,801 A * 12/1976 Bond
4,288,051 A * 9/1981 Goschel
A method and system for maximizing satellite coverage at predetermined local times for a set of predetermined geographic location includes a processor operative to determine a period of rotation for each of the desired satellites in the satellite constellation. The processor also determines a time dependent coverage of the satellite constellation based on the period of rotation and the trajectory of each of the desired satellites. The trajectories of the desired satellites are tilted until the satellite constellation provides maximum coverage at the predetermined local times for the set of predetermined geographic locations. If a new satellite constellation is being designed, command signals are programmed into a computer of a launch vehicle containing the modified trajectory. If an existing satellite constellation is being modified, the ground station transmits command signals to the satellites for modifying the trajectory of the satellites in accordance with the tilted trajectory.
21 Claims, 5 Drawing Sheets