Timing and automatic frequency control of digital receiver using the cyclic properties of a non-linear operation
US5282228A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Dec 9, 1991 |
| Grant date | Jan 25, 1994 |
| Priority date | — |
| Expiry date | Dec 9, 2011 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH04L2027/0055
- WIPO fieldDigital communication
- WIPO sectorElectrical engineering
Abstract
A technique for correcting the sampling time and carrier frequency error in a receiver for digitally modulated signals. Discrete-time, complex-valued samples of the incoming signal are fed to a pair of non-linear operators such as correlators. The first correlator provides a signal having a first phase component related to the symbol timing error and a second phase component related to the carrier frequency error. The second correlator provides a signal having a first phase component related to the symbol timing error and a second phase component related to the negative of the carrier frequency error. The phase components are then separated and detected to extract an estimate of the symbol timing error and the carrier frequency error. In the preferred embodiment, the complex-valued samples are frequency-shifted, before being fed to the correlators, so that the phase components of interest appear at zero frequency. The invention satisfactorily demodulates transmitted digital signals in applications, such as cellular time-division multiple access (TDMA), where they are susceptible to multipath fading.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.