Keeping accurate time for a hybrid GPS receiver and mobile phone when powered off
US7598909B2 · kind B2 · utility
Assignees
Inventors
Key dates
| Filing date | Sep 11, 2008 |
| Grant date | Oct 6, 2009 |
| Priority date | — |
| Expiry date | Sep 11, 2028 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG01S19/256
- WIPO fieldMeasurement
- WIPO sectorInstruments
Abstract
A hybrid navigation satellite receiver and mobile telephone uses only two crystal oscillators. One that operates a master clock around 27-MHz and that consumes milliwatts of power. The other oscillator consumes only microwatts of power and operates continuously on battery power at about 32-KHz. Only the second, low frequency oscillator is kept running during power “off”. On power “restart”, a real-time-clock counter is consulted to cause an estimate of the GPS system time to be regenerated and supplied to the GPS-DSP to quicken its initialization. The master clock is GPS-calibrated, and the accurate clock is used to drive NCO's for the mobile telephone part and host CPU.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.