| 摘要 |
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 Vin 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.
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