Method and apparatus for improving AM compatible digital broadcast analog fidelity
US5859876A · kind A · utility
Inventors
Key dates
| Filing date | Jun 27, 1996 |
| Grant date | Jan 12, 1999 |
| Priority date | — |
| Expiry date | Jun 27, 2016 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH04H2201/186
- WIPO fieldTelecommunications
- WIPO sectorElectrical engineering
Abstract
A digital signal transmission system is provided which minimizes the AM signal envelope distortion caused by multiple digitally modulated carriers in the same band as the AM signal. The system transmits an amplitude modulated signal. Digital carriers for the digital signal are placed both above and below the frequency of the analog AM carrier. Certain digital carriers that are above the frequency of the analog AM carrier have an associated digital carrier that is at an equal frequency offset below the analog AM carrier. The data and modulation placed on the upper digital carrier and its counterpart are such that the signal resulting from their addition has no component that is in-phase with the analog AM carrier. The signal envelope is predistorted to counteract the distortion added by the digital carriers.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.