| 摘要 |
PURPOSE:To obtain the best stereo separation by adjusting the demodulation level of a sub-channel signal with adding or subtracting the feedback volume of a phase locked loop, and matching the adjusted level with the level of a main channel signal. CONSTITUTION:By adding or subtracting the feedback volume at a feed-back circuit 34 in the phase locked loop which constitutes a demodulation circuit 18, the demodulation level of a sub-channel signal (L-R) is added or subtracted. For example, by providing a variable resistor 41 between terminals 36 and 28 as the feedback element of the feedback circuit 34 and adding/subtracting the resistance, the feedback volume is adjusted. Thereby, the demodulation level of the sub-channel signal (L-R) is added/subtracted against a main channel signal (L+R) and a relative ratio for each signal (L+R) and (L-R) added on a matrix circuit 16 is matched and the best stereo separation is obtained by adjusting.
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