| 摘要 |
PURPOSE:To improve the sound quality by performing the preholding, band limitation and muting for the demodulation signal in response to the drop-out period of the FM signal. CONSTITUTION:The drop-out of the FM signal is detected by a drop-out detect ing circuit DOPET9. Then a subsequent preholding circuit 6 of a DEM 5 is controlled and the demodulated audio signal is held at the value obtained imme diately before the drop-out of the FM signal. For the drop-out of a comparative ly long period, a band limit detecting circuit 10 for a comparatively long-period drop-out is used for actuation of a band limiting circuit 7. The circuit 7 drops the high band component for smoothening and deletes the harmful pulsative tones. Furthermore an MUTE circuit 8 following the circuit 7 is controlled by an MUTE detecting circuit 11 for discontinuation of output against a longer a drop-out period.
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