| 摘要 |
PURPOSE:To remove the overshoot of a control voltage and to speed up a channel selection by providing a gate circuit which puts the output of a phase detector into ON/OFF according to the output of a reference frequency oscillator controlled by a computer in the phase detector. CONSTITUTION:A high frequency signal, received by an antenna 1 is inputted to a tuner 2. When a channel selecting operation is operated, at first, a microcomputer 7 sets a programable frequency divider 6 to the division radio of a local oscillation frequency of the selected channel. Besides, the gate circuit 13 is made beforehand to repeat to put the phase detector 9 into ON/OFF at the output cycle of a reference frequency oscillation circuit 8 by the computer 7, and at every ON, the output of the detector 9 is impressed to the terminal 4 of the local oscillator 3 through a tuning amplification circuit 10 and a low- pass filter 11. Then, the potential of the terminal 4 is elevated gradually, and is settled stably at the value in which it reaches the potential of the selected channel.
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