US 5,589,877 A · Automatic amplitude control circuit for a vector scope

Abstract

A signal processing circuit for a vector scope adapted to display and measure characteristics of a color video signal on a screen which comprises a variable gain circuit 3, a demodulation circuit 6, timing signal generator 7, amplitude detection circuits 8,9, memory 12 storing a reference amplitude and CPU11. An input signal V.sub.in through the variable gain circuit is supplied to demodulation circuiting from where chrominance components R-Y, B-Y are provided to the amplitude detection circuits. When the timing signal is provided to the amplitude detection circuits, the circuits detect their amplitudes. The CPU computes an amplitude of a burst signal in accordance with the detected amplitudes and the difference between the computed amplitude and the reference amplitude stored in the memory. If the difference is not zero, the CPU controls the variable gain circuit so that it become zero.

Claims16

Dependent claims

A signal processing circuit for a vector scope adapted to display and measure characteristics of a color video signal on a screen therein comprising:

(a) variable gain means for varying a gain of said color video signal input to the signal processing circuit;
(b) chrominance signal generation means, in response to a signal output from said variable gain means, for detecting and generating first and second chrominance signals;
(c) first detection means, in response to said first and second chrominance signals, for detecting an amplitude of a burst signal contained in the color video signal;
(d) first memory means for previously storing a reference amplitude of said burst signal;
and
(e) gain adjusting means for comparing the amplitude of said burst signal detected by said first detection means with said reference amplitude stored in said first memory means and adjusting the gain at said variable gain means so that they coincide with each other.

3 more elements

A signal processing circuit for a vector scope adapted to display and measure characteristics of a color video signal on a screen therein comprising:

(a) variable gain means for varying a gain of said color video signal input to the signal processing circuit;
(b) chrominance signal generation means, in response to a signal output from said variable gain means, for detecting and generating first and second chrominance signals;
(c) first detection means, in response to said first and second chrominance signals, for detecting an amplitude of a chroma signal contained in the color video signal;
(d) first memory means for previously storing a reference amplitude of said chroma signal;
and
(e) gain adjusting means for comparing the amplitude of said chroma signal detected by said first detection means with said reference amplitude stored in said first memory means and adjusting the gain at said variable gain means so that they coincide with each other.

3 more elements

A signal processing circuit for a vector scope adapted to display and measure characteristics of a color video signal on a screen therein comprising:

(a) variable gain means for varying a gain of said color video signal input to the signal processing circuit;
(b) chrominance signal generation means, in response to a signal output from said variable gain means, for detecting and generating first and second chrominance signals;
(c) first detection means, in response to said first and second chrominance signals, for selectively detecting amplitudes of burst and chroma signals contained in the color video signal;
(d) second detection means, in response to said first and second chrominance signals, for selectively detecting phases of said burst and chroma signals;
(e) memory means for previously storing reference amplitudes and phases of said burst and chroma signals;
(f) gain adjusting means for comparing the amplitude of said burst or chroma signal selectively detected by said first detection means with the corresponding reference amplitude stored in said memory means and adjusting the gain at said variable gain means so that they coincide with each other;
and
(g) phase adjusting means for comparing the phase of said burst or chroma signal selectively detected by said second detection means with the corresponding reference phase stored in said memory means and adjusting a phase-shift value of a sub-carrier at a phase-shift means included in said chrominance signal generation means so that they coincide with each other.

5 more elements

Dependencies are inferred from the claim text.

Automatic amplitude control circuit for a vector scope

Life of this patent

Automatic amplitude control circuit for a vector scope

Life of this patent

Abstract

Claims16