Method and apparatus for AM compatible digital broadcasting
US5588022A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Mar 7, 1994 |
| Grant date | Dec 24, 1996 |
| Priority date | — |
| Expiry date | Mar 7, 2014 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH04L27/26035
- WIPO fieldDigital communication
- WIPO sectorElectrical engineering
Abstract
A broadcasting method for simultaneously broadcasting analog and digital signals in a standard AM broadcasting channel is provided by: broadcasting an amplitude modulated radio frequency signal having a first frequency spectrum, wherein the amplitude modulated radio frequency signal includes a first carrier modulated by an analog program signal; and simultaneously broadcasting a plurality of digitally modulated carrier signals within a bandwidth which encompasses the first frequency spectrum, each of the digitally modulated carrier signals being modulated by a portion of a digital program signal, wherein a first group of the digitally modulated carrier signals lying within the first frequency spectrum are modulated in-quadrature with the first carrier signal, and wherein second and third groups of the digitally modulated carrier signals lie outside of the first frequency spectrum and are modulated both in-phase and in-quadrature with the first carrier signal. Transmitters and receivers which operate in accordance with the above method are also provided.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.