Frame-based sign inversion method and system for spectral shaping for pulse-coded-modulation modems
US6343101B1 · kind B1 · utility
Assignee
Inventors
Key dates
| Filing date | Jan 16, 1998 |
| Grant date | Jan 29, 2002 |
| Priority date | — |
| Expiry date | Jan 16, 2018 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH04B14/04
- WIPO fieldTelecommunications
- WIPO sectorElectrical engineering
Abstract
A spectral shaping PCM modem communication system uses a symbol encoder to encode a data bit stream into a PCM symbol stream. A plurality of different frames are formed from the PCM symbol stream. Performance metrics are computed for each possible frame and its inversion so a decision can be made in order to select a most desirable frame and inversion. Delays are injected in the data flow to allow a look-ahead and thus provide for better frame selection and inversion decisions. A channel multiplexer combines decision bits and output frames to form encoded output frames that are fed to a digital channel connected to a telephone network wherein they are converted to analog signal. A corresponding decoder converts analog signals from the telephone network to digital signals. A timing recovery and equalization means corrects sample timing and removes inter-symbol interference effects introduced by telephone networks. The output of the equalizer is sampled at correct timing to recover the received samples and received frame. A channel de-multiplexer separates the frame selection and frame inversion decision bits from the symbol frames received. Inversion and framing decisions are discer…
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.