| 摘要 |
PURPOSE:To reduce the deterioration in sound quality due to transient state of a low-pass filter by switching properly the circuit so that a pre-value hold correction is applied to a low-frequency component of a reproduced sound signal and zero value hold correction is applied to a high frequency component. CONSTITUTION:A demodulated sound signal 100 is inputted to a holding capacitor 2 and an amplifier 3 via a switch 1 and outputted via an LPF4 as a reproduced signal from which noise are rejected. If the frequency component of the signal 100 is biased toward high frequencies, a large signal turns on a switch 6 via an LPF7 and a detector 8. If the component is biased toward low frequencies conversely, the switch 6 is turned off. A dropout (DO) takes place in the demodulation signal and a DO signal 200 falls down, then a switch 1 is turned off. When the signal 100 is biased toward high frequencies, since the switch 6 is turned on, zero value hold is applied by a resistor 5 and capacitor 2. On the other hand, when the component is biased toward low frequencies, since the switch 6 is turned off and pre-value hold is attained. |
