FM modulator
US4816781A · kind A · utility
Assignee
Inventor
Key dates
| Filing date | Jun 22, 1987 |
| Grant date | Mar 28, 1989 |
| Priority date | — |
| Expiry date | Jun 22, 2007 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH03C2200/0079
- WIPO fieldAudio-visual technology
- WIPO sectorElectrical engineering
Abstract
Circuitry for producing an extremely linear frequency modulated audio carrier for use in the head end of a video signal distribution system, such as a cable television system. A reference oscillator operating at a relatively high frequency, such as the video carrier frequency, generates a signal which is divided down to a relatively low frequency. A voltage controlled oscillator operating at the relatively low frequency is used to frequency modulate the audio signal. After modulation, the audio carrier is upconverted utilizing a signal frequency which is also derived from the original reference frequency, thus providing a stable and linear frequency modulated audio carrier particularly suitable for transmission of stereo program audio.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.