Method and apparatus for digital vector QAM modulator
US7492832B2 · kind B2 · utility
Assignee
Inventors
Key dates
| Filing date | Mar 10, 2004 |
| Grant date | Feb 17, 2009 |
| Priority date | — |
| Expiry date | Dec 28, 2026 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH04L27/362
- WIPO fieldDigital communication
- WIPO sectorElectrical engineering
Abstract
Direct digital QAM modulation at an RF frequency is obtained from digitally synthesized RF signals which are generated for use as the two vectors. The two vectors are individually controlled in phase and summed to provide a combined phase and amplitude modulation that forms the modulated signal. The synthesized RF signal is generated from a higher reference frequency using a variable pulse stretching technique implemented with programmable delay lines. The amount of the pulse stretch in each cycle is controlled by a phase increment value. Pulse stretching can be extended beyond one cycle by pulse swallowing, allowing the generation of an RF signal from DC up to and including the input reference frequency. Phase modulation is added by digital control of the pulse stretching according to the phase modulation data bits.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.