Title:
衛星クロックの無線リンク制御
Document Type and Number:
Japanese Patent JP3657004
Kind Code:
B2
Abstract:
A system and method for maintaining a precise time standard among a system of orbiting satellites is disclosed. In an illustrative embodiment, atomic clock data is circulated among the satellites via RF crosslinks. Each satellite uses the received data as input to a Kalman process which acts to minimize the mean squared error among the satellite clocks to form a set of "ensemble clocks". The resulting ensemble clock values are then transmitted to an earth station where an offset between the ensemble clocks and Universal Time is computed. The offset is transmitted from the earth station to the satellites where it is used by the satellites to lock their on-board clocks to Universal Time, thereby creating a corrected system time. The corrected system time is transmitted, via RF crosslinks, to satellites not having operational on-board clocks. The satellites without atomic clocks employ phase locked loops to anchor their clocks to the corrected system time as it is received over the crosslinks.
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Inventors:
Kumisky, Peter
Epstein, Marvin A
Doyle, Lawrence Jay
Epstein, Marvin A
Doyle, Lawrence Jay
Application Number:
JP50125196A
Publication Date:
June 08, 2005
Filing Date:
June 01, 1995
Export Citation:
Assignee:
International Standard Electric Corporation
International Classes:
G01S19/09; G01S19/42; G04G5/00; G04R20/00; G04R20/04; G04R40/02; H04B7/15; H04B7/212; H04L7/00; (IPC1-7): G04G7/02; G01S5/14; G04G5/00; H04B7/15; H04L7/00
Domestic Patent References:
| JP6160508A | ||||
| JP7012966A | ||||
| JP5155397A | ||||
| JP1500714A | ||||
| JP1501512A |
Attorney, Agent or Firm:
Takehiko Suzue
Sadao Muramatsu
Atsushi Tsuboi
Ryo Hashimoto
Toshio Shirane
Sadao Muramatsu
Atsushi Tsuboi
Ryo Hashimoto
Toshio Shirane