System and method for frequency management in a communication device having a positioning device
US6741842B2 · kind B2 · utility
Assignee
Inventors
Key dates
| Filing date | Sep 30, 2002 |
| Grant date | May 25, 2004 |
| Priority date | — |
| Expiry date | Sep 30, 2022 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH04B1/3805
- WIPO fieldMeasurement
- WIPO sectorInstruments
Abstract
A frequency management scheme for a hybrid cellular/GPS or other device generates a local clock signal for the communications portion of the device, using a crystal oscillator or other part. The oscillator output may be corrected by way of an automatic frequency control (AFC) circuit or software, to drive the frequency of that clock signal to a higher accuracy. Besides being delivered to the cellular or other communications portion of the hybrid device, the compensated clock signal may also be delivered to a comparator to measure the offset between the cellular oscillator and the GPS oscillator. The error in the cellular oscillator may be measured from the AFC operation in the cellular portion of the device. An undershoot or overshoot in the delta between the two oscillators may thus be deduced to be due to bias in the GPS oscillator, whose value may then be determined. That value may then be used to adjust Doppler search, bandwidth or other GPS receiver characteristics to achieve better time to first fix or other performance characteristics.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.