| 摘要 |
PURPOSE:To improve clip distortion of an FM luminance signal and to have contour emphasis effect by constituting a pre-emphasis circuit and a de-emphasis circuit of two delay lines, an adder, subtractor, and a level regulator. CONSTITUTION:A pre-emphasis circuit is composed of delay lines 21 and 22, subtractors 23 and 24, adders 25 and 26, and level regulators 27 and 28. When this structure is compared with conventional one; a white peak goes to peaks 151 and 152, black peak goes to peaks 161 and 162, and two peaks go to about 1/2 in size, thereby a clip amount is made small. In case of a de-emphasis circuit, a difference from the pre-emphasis circuit is that level regulators 31 and 32 are incorporated. In overall characteristics of both circuits, the phase changes in proportion to the frequency, thereby causing no waveform distortion.
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