Apparatus and methods for QAM modulation using dual polar modulation
US8660208B2 · kind B2 · utility
Assignee
Inventors
Key dates
| Filing date | Oct 19, 2010 |
| Grant date | Feb 25, 2014 |
| Priority date | — |
| Expiry date | Nov 19, 2031 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH04L27/36
- WIPO fieldDigital communication
- WIPO sectorElectrical engineering
Abstract
Apparatus and methods for QAM modulation are disclosed using dual polar modulation. QAM modulation of a signal is accomplished by translating a QAM signal into two phasors having the same or constant amplitude and then phase shifting one of the phasor by 180 degrees for a differential load. The phasors are then polar modulated such that, when differentially combined in the load through summation or superposition, a QAM modulated symbol results. The use of constant amplitude phasors when power amplified for transmission of QAM modulated signals allows amplifiers to be operated in a saturation mode with greater efficiency than conventional amplifiers used in QAM modulation, which operate in a less efficient linear mode to effect amplitude modulation. Additionally, differential combining of the phasors affords relaxation of the turns of a transformer used in amplifying the phasors.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.