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 Title: |
US5936570:
Low-earth orbit satellite acquisition and synchronization system using a beacon signal
[ Derwent Title ]
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| Country: |
US United States of America
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| Inventor: |
Ghazvinian, Farzad; Mercer Island, WA
Sturza, Mark A.; Encino, CA
Hinedi, Sami M.; Bellevue, WA
Sarrafan, Shiva S.; Issaquah, WA
Shah, Biren N.; Kirkland, WA
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| Assignee: |
Teledesic LLC, Kirkland, WA
other patents from TELEDESIC LLC (746777) (approx. 21)
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| Published / Filed: |
1999-08-10
/ 1998-03-05
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| Application Number: |
US1998000035692
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| IPC Code: |
Advanced:
H04B 7/185;
H04B 7/204;
H04B 7/212;
Core:
more...
IPC-7:
H04B 7/185;
H04B 7/19;
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| ECLA Code: |
H04B7/185M4; H04B7/204B; H04B7/212B;
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| U.S. Class: |
Current:
342/354;
342/356;
342/359;
455/013.2;
Original:
342/354;
342/356;
342/359;
455/013.2;
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| Field of Search: |
342/352,354,356,359
455/12.1,13.2
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| Priority Number: |
| 1998-03-05 |
US1998000035692 |
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| Abstract: |
A system for acquiring the beacon of a satellite and synchronizing data transmission between the satellite and a ground terminal is disclosed. The ground terminal conducts a search for a satellite to be acquired. The search may be based on previously developed information from which the location of the satellite can be predicted and, thus, limited to a small area of the sky, or cover a large area of the sky in accordance with a search routine. After the beacon of a satellite is acquired, the geographic area served by the satellite is determined. If the satellite does not serve the cell within which the ground terminal is located, a further satellite search is conducted, which may be based in part on information contained in the beacon of the acquired satellite. After the satellite serving the cell containing the ground terminal is acquired, a test is made to determine how long the satellite will continue to cover the cell. If the time period is short, communication waits until the next satellite to cover the cell is acquired. If the time period is long, communication is allowed to begin. The beacon is also used by the ground terminal to: (i) accurately time uplink data transmissions; (ii) estimate uplink Doppler, Doppler rate, and Doppler rate derivative and use this information to pre-compensate the carrier frequency of the uplink data transmissions for Doppler variations; and (iii) estimate the carrier frequency of downlink data transmission(s) by continuously tracking the beacon carrier frequency and scaling the result by a suitable scaling factor.
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| Attorney, Agent or Firm: |
Christensen O'Connor Johnson & Kindness PLLC ;
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| Primary / Asst. Examiners: |
Issing, Gregory C.; Phan, Dao L.
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| Maintenance Status: |
E1 Expired Check current status
CC Certificate of Correction issued
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| INPADOC Legal Status: |
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| Designated Country: |
AL AM AP AT AZ BA BB BG BR BY CA CH CN CU CZ DE DK EA EE EP ES FI GB GD GE GH GM HR HU ID IL IN IS JP KE KG KP KR KZ
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| Family: |
Show 5 known family members
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First Claim:
Show all 31 claims |
The embodiments of the invention in which an exclusive property or privilege is claimed are defined as follows:
1. A ground terminal beacon acquisition and synchronization system for a satellite communication network comprising a plurality of orbiting satellites and a plurality of ground terminals that communicate with one another via uplink and downlink data channels to and from the orbiting satellites, each of said orbiting satellites producing a beacon, said ground terminal beacon acquisition and synchronization system comprising:
- (a) an antenna;
- (b) a satellite acquisition system for:
- (i) pointing said antenna toward a predicted satellite position and determining if a satellite is located at a predicted satellite position based on whether a beacon is emanating from said predicted satellite position;
- (ii) if no satellite is located at the predicted satellite position, causing the antenna to point toward another predicted satellite position and determining if a satellite is located at said another predicted satellite position based on whether a beacon is emanating from said another predicted satellite position;
- (iii) if a satellite is located at the predicted satellite position, determining if the satellite is serving the geographic area in which the ground terminal lies based on information contained in the beacon; and
- (iv) if the satellite is not serving the geographic area in which the ground terminal lies, causing the antenna to point toward still another predicted satellite position and determining if a satellite is located at said still another predicted satellite position based on whether a beacon is emanating from said still another satellite position; and
- (v) repeating (ii) through (iv) until the satellite serving the geographic area in which the ground terminal lies is located; and
- (c) a synchronization system for synchronizing the ground terminal to the satellite serving the geographic area in which the ground terminal lies based on information contained in the beacon.
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| Background / Summary: |
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| Drawing Descriptions: |
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| Description: |
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| Forward References: |
Show 17 U.S. patent(s) that reference this one
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