Satellite controlled digital clock system
US4014166A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Feb 13, 1976 |
| Grant date | Mar 29, 1977 |
| Priority date | — |
| Expiry date | Feb 13, 1996 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG04R20/06
- WIPO fieldMeasurement
- WIPO sectorInstruments
Abstract
A method and apparatus are provided for maintaining and correcting a time ference in a satellite controlled digital clock system. A time code message including time-of-year information and satellite position information is transmitted in a data stream from a transmitter on earth to a satellite orbiting the earth to be relayed back to receivers located around the world. The data is transmitted at a precise data rate. According to the invention, a local clock oscillator is phase locked with the precise data rate, thereby providing the clock system with time-of-year information by counting the pulses produced by the local oscillator. At the same time, the digital clock system assembles the time code message from the received data stream and compares the message with the time accumulated by counting the pulses produced by the oscillator. After a predetermined number of errors are detected by such comparisons, the clock system resets itself to coincide with the received time code message. If transmission of the time code message is interrupted, the clock continues counting pulses produced by the local oscillator and thereby continues keeping time undisturbed. In a preferred embodiment, …
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.