Audio-video modulator system on IC chip
US5079525A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Dec 6, 1990 |
| Grant date | Jan 7, 1992 |
| Priority date | — |
| Expiry date | Dec 6, 2010 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH03C5/00
- WIPO fieldAudio-visual technology
- WIPO sectorElectrical engineering
Abstract
An RF modulator comprising an FM modulator supplied with an audio signal, and AM modulator supplied with the FM modulator output and a video signal, an oscillator for generating a sound subcarrier signal, and an oscillator for generating a main carrier signal. Each of the oscillators consists of a VCO with a PLL circuit, and the entire components are composed of a single IC chip so as to be formed into a compact miniature structure. A modified RF modulator includes a PLL circuit for varying the oscillation frequency of a VCO by a variable frequency divider, and a modulation circuit supplied with a modulating signal and the oscillation output of the VCO. The division ratio (integer) of the variable frequency divider is continuously varied, and the reference frequency of a reference oscillator is set to be less than a predetermined channel interval frequency, thereby reducing the frequency error in the modulated signal output.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.