| 摘要 |
PURPOSE:To expand the utility of a channel number by making a frequency of a transmission high frequency signal coincident with a reception frequency of an equipment and making a frequency of a reception high frequency signal coincident with a transmission frequency of the equipment. CONSTITUTION:The oscillating frequency itself of a voltage controlled oscillator (VCO) 5a of a phase locked loop circuit 5 is optionally changed by varying,e.g. a capacitance of a varactor diode in a tuning circuit with a voltage applied to a control terminal. Furthermore, the oscillating frequency of the VCO 5 is stepwise selected in response to a frequency switching signal. Furthermore, a circuit 5b such as a phase comparator changes an oscillating frequency of the phase locked loop circuit 5 by rewriting internal data when a channel is revised. Thus, a frequency of a transmission high frequency signal is made coincident with a reception frequency of an equipment at the transmission and a frequency of a reception high frequency signal is made coincident with a transmission frequency of the equipment at the reception. |
