Compatible digital audio for NTSC television
US5357284A · kind A · utility
Assignee
Inventor
Key dates
| Filing date | Mar 29, 1990 |
| Grant date | Oct 18, 1994 |
| Priority date | — |
| Expiry date | Mar 29, 2010 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH04N7/06
- WIPO fieldAudio-visual technology
- WIPO sectorElectrical engineering
Abstract
A method and apparatus for transmitting a digitally modulated Quadrature Phase Keyed (QPSK) audio carrier signal, or a digitally modulated Quadrature Partial Response System (QPRS) audio carrier signal, wherein the audio carrier signal is located 1.2 MHz below the video carrier of an NTSC signal. This places the digital audio signal 300 KHz above the analog FM sound center frequency of the NTSC signal in the adjacent lower channel, 4.8 MHz above the video carrier of the adjacent lower channel NTSC signal and at the edge of the lower vestigal video sideband components of the NTSC signal with which the digital audio signal is associated.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.