| 摘要 |
PCT No. PCT/JP96/00427 Sec. 371 Date Nov. 13, 1997 Sec. 102(e) Date Nov. 13, 1997 PCT Filed Feb. 23, 1996 PCT Pub. No. WO96/39777 PCT Pub. Date Dec. 12, 1996An automatic image quality-controlling device, where an FM signal output from a video head is amplified in an AGC amplifier to a uniform amplitude level. A lower-sideband variable peaking amplifier peaks the lower-sideband spectrum of the FM signal at about 1.5 MHz. The lower-sideband is then extracted through a lower-sideband filter. The amplitudes of the lower sideband are converted into a d.c. voltage, which is compared with a reference voltage to output an error voltage to feed back to the lower-sideband variable peaking amplifier so that the ratio between the magnitudes of the carrier wave and the lower-sideband component of the FM signal to be demodulated are constant. As a result, previously jutting amplitudes of the lower-sideband spectrum of an FM signal are uniform to allow optimal S/N value and excellent resolution, thereby producing sharp images.
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