Mode selective quadrature amplitude modulation communication system
US5363408A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Mar 24, 1992 |
| Grant date | Nov 8, 1994 |
| Priority date | — |
| Expiry date | Mar 24, 2012 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH04N5/211
- WIPO fieldAudio-visual technology
- WIPO sectorElectrical engineering
Abstract
A quadrature amplitude modulation (QAM) communication system is provided in which data can be communicated in any one of a plurality of QAM modes, such as 16-QAM, 32-QAM, and 64-QAM. A receiver detects the particular QAM mode transmitted on a trial and error basis, by attempting to decode the received data using different QAM modes until a synchronization condition is detected. The synchronization condition can require that a plurality of different synchronization tests be met. In a specific embodiment, a first synchronization test is met when a renormalization rate of a trellis decoder is below a threshold value. A second synchronization test is met when a first synchronization word is detected in the received data. A third and final synchronization test is met when a second synchronization word is detected in the received data. In order to reduce the cost of the receiver, most of the QAM mode dependent components are implemented using look-up tables stored in PROMs.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.