Computing network path delays so accurate absolute time can be forwarded from a server to a client
US6941109B2 · kind B2 · utility
Assignees
Inventors
Key dates
| Filing date | Feb 19, 2002 |
| Grant date | Sep 6, 2005 |
| Priority date | — |
| Expiry date | Jul 25, 2023 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH04J3/0667
- WIPO fieldTelecommunications
- WIPO sectorElectrical engineering
Abstract
A navigation-satellite receiver support data network comprises a server connected to the Internet to provide initialization information to clients for faster cold starts. The server includes a GPS receiver that provides for tracking of a constellation of navigation satellites. When a client is started cold, time and frequency are initially unknown to it. Test messages are sent back and forth over the Internet and a path delay time is computed from the average of the quickest transit times. This yields the offset time between the server's time system and the client's time system. The server sends current time information to the client, and the computed path delay is added. The client can then compute correct time from the server and path delay information, and thereby select much sooner which satellites are correct to search.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.