Carrier acquisition scheme for QAM and QPSK data
US5042052A · kind A · utility
16Cited by
12References
9Claims
0Family size
Assignee
Inventors
Key dates
| Filing date | Feb 16, 1990 |
| Grant date | Aug 20, 1991 |
| Priority date | — |
| Expiry date | Feb 16, 2010 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH04L2027/0051
- WIPO fieldDigital communication
- WIPO sectorElectrical engineering
Abstract
The invention involves an apparatus for recovering the carrier signal in OPSK or QAM data. First an energy directed phase detector controls a voltage controlled oscillator so that the output signal has a phase that is within a few degrees of the carrier phase. Following this coarse acquisition, the system clock timing is recovered and established. A decision directed phase detector, using the system clock information, then controls the VCO to adjust the output signal phase to within a very small tolerance of the actual carrier phase.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.