| 摘要 |
PURPOSE: To constitute various decoders by changing over a switch. CONSTITUTION: A wide band extension circuit 44 is provided with a signal path having an LPF 48, (L-R) demodulator 52, LPF 10 and voltage controlled amplifier 18. The gain of amplifier 18 is controlled by a control signal 58 received from a demodulation difference signal under the operation of BPF 20 and an integration peak detector 26. The output of amplifier 18 is supplied to a de-emphasis circuit 24, supplied to a stereo matrix circuit 38 later and synthesized with a stereo signal (L+R) of sum and source signals L and R are reproduced. When a DBX extension circuit 60 is connected and used in place of de-emphasis circuit 24, the control signal 58 of amplifier 18 to perform wide band extension is canceled by a predetermined voltage, the BPF 20 disables operation, the input is switched and the LPF 48 is bypassed. |
