| 摘要 |
PURPOSE:To enable the reception with one set of tuner, by alternately receiving priority channel and arbitrary channel and monitoring the priority channel in a short time for a given time interval, when the priority channel is first received. CONSTITUTION:A code selection circuit 1 outputs a two signal codes so that the priority channel and arbitrary channel can alternately be received in the duty cycle of 50% when the priority channel code is not input. Further, when an arbitrary channel is received, since the circuit 1 outputs a signal of low level to the terminal 1', a high level signal is input to one input terminal of an NAND circuit 12. Further, since the squeltch signal is at high level, the signal of low level is input to the terminal 8' of the counter circuit 8, the output of the circuit 8 is changed to change the duty cycle of the circuit 1, and the code is output so that the priority channel is received in a short time for a given time interval. With this state, when the signal in the priority channel is received, the oscillation of a pulse oscillator 9 is stopped and the channel is fixed to the priority channel. |
