Method for reducing the out-of-band emission in AM transmitters for digital transmission
US7248639B2 · kind B2 · utility
Assignee
Inventors
Key dates
| Filing date | Jan 17, 2002 |
| Grant date | Jul 24, 2007 |
| Priority date | — |
| Expiry date | Dec 10, 2023 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH04H20/46
- WIPO fieldTelecommunications
- WIPO sectorElectrical engineering
Abstract
A method for reducing out-of-band emission in an AM transmitter for digital transmission includes generating, from a digital modulation signal, an amplitude signal and a phase-modulated radio frequency signal configured to control the AM transmitter. A digital modulation process is used in which a hole is formed around a 0/0 point so that a zero crossing is avoided by a substantial margin in a vector diagram representation. Thereby a respective bandwidth of the amplitude signal and the phase-modulated radio frequency signal is limited so that the out-of-band emission decreases as a function of a shoulder distance achievable by the AM transmitter at a rate where a spectrum mask is not exceeded.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.