RF link control of satellite clocks
US5506781A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Jun 3, 1994 |
| Grant date | Apr 9, 1996 |
| Priority date | — |
| Expiry date | Jun 3, 2014 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH04B7/2125
- WIPO fieldTelecommunications
- WIPO sectorElectrical engineering
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.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.