| 摘要 |
PURPOSE:To use sufficiently the dynamic range of an A/D converter by detecting and controlling the level of the corresponding signal converted to a digital signal or the special level in the signal for adjusting the gain of the signal of the first and second bands included in the signal. CONSTITUTION:The gain is adjusted by a gain adjusting device 9 of the compound color video signal inputted from a terminal 8, chrominance components are extracted from the video signal by a band filter 10, the gain of the chrominance signal is adjusted by a gain adjusting device 11, overlapped by the same phase or the reverse phase and converted to a digital signal by an A/D converter 12. Next, the luminance signal is extracted by a low-pass filter 13, and chrominance signal are extracted by a low-pass filter 14. The level of the luminance signal is detected by a level detecting device 15, converted to the analog signal by a D/A converter 16 and the gain adjusting device 9 is controlled. The level of the chrominance signal is detected by a level detecting device 17, converted to the analog signal by a D/A converter 18 and a gain adjusting device 11 is controlled. Thus, the input level of the A/D converter is stable, and the dynamic range can be sufficiently used.
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