Digital modulation process and modulator implementing the process
US6459742B1 · kind B1 · utility
Assignee
Inventors
Key dates
| Filing date | Feb 4, 1999 |
| Grant date | Oct 1, 2002 |
| Priority date | — |
| Expiry date | Feb 4, 2019 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH04L25/03834
- WIPO fieldDigital communication
- WIPO sectorElectrical engineering
Abstract
The successive symbols of a digital stream are converted into phase increments which are accumulated. A modulating phase is obtained by filtering the accumulated phase. A complex signal is produced whose argument represents the modulating phase. Two quadrature radio waveforms are respectively modulated on the basis of that complex signal, and a radio signal resulting from a combination of the two modulated waveforms is transmitted. The complex signal may be filtered digitally. Its real and imaginary components are converted into analog form, and are subjected to anti-aliasing analog filtering and then mixed with the two radio waveforms. Appropriate sizing of the digital filters provides efficient modulation with small envelope variations, causing little adjacent channel interference and a low error rate.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.