| 摘要 |
PURPOSE:To accelerate a channel selecting action by confirming the presence of a station detecting signal after detecting the down signal only in a search mode and then the center or up signal. CONSTITUTION:A VCO4 scans the local oscillation frequency by the output of a control circuit 11 for a period when the down signals are detected successively from an end through the other end of a prescribed set range by the steps of the prescribed frequency with an AFT detecting circuit 8. Then the presence or absence of the center and up signals is detected when no down signal is detected any more. A station detecting signal generating circuit 10 detects the presence or absence of a station detecting signal SD when the center or up signal is detected. The fine tuning is carried out when the signal SD is detected. This can accelerate a channel selecting action. |
