Digital audio scrambling system with pulse amplitude modulation
US4752953A · kind A · utility
Assignees
Inventors
Key dates
| Filing date | Aug 11, 1986 |
| Grant date | Jun 21, 1988 |
| Priority date | — |
| Expiry date | Aug 11, 2006 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH04K1/02
- WIPO fieldAudio-visual technology
- WIPO sectorElectrical engineering
Abstract
In a system for scrambling an audio signal for transmission with a video signal having non-video information intervals, an analog audio signal is converted into a scrambled compressed digital audio signal; individual bits from the scrambled compressed digital audio signal are combined to provide 2-bit digital words; each digital word is converted into an 8-bit digital PAM data signal having a binary value bearing a predetermined relationship to the binary value of the converted 2-bit digital word; the 8-bit digital PAM data signal is converted into a 4-level PAM analog signal; and the PAM analog signals are inserted into the non-video information intervals of the video signal for transmission. A descrambling system descrambles the 4-level PAM analog signals by a complementary scheme.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.