Offset correction
US5081652A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Apr 4, 1990 |
| Grant date | Jan 14, 1992 |
| Priority date | — |
| Expiry date | Apr 4, 2010 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH04L27/2272
- WIPO fieldDigital communication
- WIPO sectorElectrical engineering
Abstract
A radio receiver includes apparatus for correcting phase and frequency offsets in a digitally modulated carrier signal. The receiver includes processing circuitry which outputs a baseband signal at point. The circuitry includes a local oscillator generating a signal intended to have a phase and frequency related (e.g. substantially equal) to the carrier signal. The baseband signal from the circuitry is input to a demodulator which generates a signal in the form of a sequence of digits corresponding to the original carrier signal. The baseband signal is sampled by a sampler and the demodulated signal is sampled by a sampler. Processing circuitry calculates the correlation function of the two sample signals and determines the value of the phase .PHI..sub.x at a time when the correlation function is a maximum. A control signal V.sub.c indicative of the phase .PHI..sub.x is generated by a signal generator and applied to the oscillator whereby the phase of the oscillator output signal is adjusted by an amount corresponding to the phase offset. Preferably, sampling is effected on at least two occasions. The phase differences determined on each correlation are subtractively combined and t…
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.