Audio-video modulator system on IC chip

Details Audio-video modulator system on IC chip Audio-video modulator system on IC chip

1990-12-06

1992-01-07

Grimm, Siegfried H.

Modulators

Frequency modulator

Plural modulation

332127, 455102, 455119, 358 23, 358330, 360 29, 370 11, 370121, H04N 540

Patent

active

050795252

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.

REFERENCES:
patent: 3775554 (1973-11-01), Hjortzberg
patent: 4654607 (1987-03-01), Ishikawa

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