Client-aiding with cellphones in a 150-KM radius area
US7200414B2 · kind B2 · utility
Assignees
Inventors
Key dates
| Filing date | Aug 7, 2002 |
| Grant date | Apr 3, 2007 |
| Priority date | — |
| Expiry date | Mar 5, 2024 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG01S19/05
- WIPO fieldMeasurement
- WIPO sectorInstruments
Abstract
A cellphone system comprises a GPS reference station located with a telephone cell site. Such GPS reference station tracks the GPS satellites visible to its local area and estimates the Doppler for each such GPS satellite. The system also includes mobile GPS receivers and cellphones that move around and through the operational area of the cell site. It is assumed that the satellite Dopplers seen by the GPS reference station will have insubstantial differences with the true Dopplers observed by other GPS receivers operating within the cell site's service area. The Doppler estimates are thus routinely communicated over a wireless telephone channel to the mobile GPS receivers and cellphones that register locally. Such mobile GPS receivers then can confidently adopt the surrogate Doppler estimates as a center starting point for their initialization frequency searches. The time required for such mobile GPS receivers and cellphones to initialize and provide a first fix is thereby substantially reduced.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.