Apparatus and method for calibrating local oscillation frequency in wireless communications
US6704555B2 · kind B2 · utility
Assignee
Inventors
Key dates
| Filing date | Mar 12, 2001 |
| Grant date | Mar 9, 2004 |
| Priority date | — |
| Expiry date | Jan 20, 2022 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH04L2027/0087
- WIPO fieldDigital communication
- WIPO sectorElectrical engineering
Abstract
According to a disclosed embodiment, a receiver comprising a digital rotator in combination with a frequency error discriminator in a digital automatic frequency control loop is used to arrive at accurate digital values used to calibrate a local oscillation frequency. A frequency error in the oscillation frequency of a local frequency generation loop causes a change in the baseband input signal frequency. The change in the baseband input signal frequency related to the frequency error in the local frequency generation loop can be detected as a phase rotation by the frequency error discriminator. By using the digital automatic frequency control loop, the frequency error introduced by the local frequency generation is determined with accuracy. The frequency error and corresponding control bits are entered into a calibration table. The calibration table may be used to adjust the local oscillation frequency for temperature changes, pilot frequency searching, and quick paging.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.