Digital variable symbol timing recovery system for QAM
US5878088A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Apr 10, 1997 |
| Grant date | Mar 2, 1999 |
| Priority date | — |
| Expiry date | Apr 10, 2017 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH04L7/0335
- WIPO fieldDigital communication
- WIPO sectorElectrical engineering
Abstract
A receiver is arranged for receiving a transmitted quadrature amplitude modulated (QAM) signal representing successive symbols, and including an in-phase (I) component and a quadrature (Q) component. In such a receiver, a timing recovery system includes a source of samples representing the QAM signal produced at a fixed frequency. A first chain of processing circuitry for the I component includes a first demodulator, coupled to the sample source, for demodulating the I component of the QAM signal to baseband; and a first interpolator, coupled to the first demodulator and responsive to a control signal, for producing I component samples taken at times synchronized to the transmitted symbols. A second chain of processing circuitry for the Q component includes a second demodulator, also coupled to the sample source, for demodulating the Q component of the QAM signal to baseband; and a second interpolator, coupled to the second demodulator and responsive to a control signal, for producing Q component samples taken at times synchronized to the transmitted symbols. A phase error detector is coupled to the first and the second interpolators, and detects the phase error between the sample …
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.