PURPOSE: To facilitate a countermeasure to entire time-divided slots without necessitating a complicated high speed synthesizer circuit by providing two systems, two local oscillators and two synthesizer circuits, and alternately switching the two systems corresponding to each slot.

CONSTITUTION: A first local oscillator 27 is frequency-locked by the prescribed oscillation frequency of a slot AT by a synthesizer circuit 34, and the signal of a prescribed frequency is transmitted from a switching means 29 to a third intermediate frequency converter 18. The first local oscillator 27 doesn't transmit a slot BT, and the synthesizer circuit 34 runs in the prescribed oscillation frequency of a slot CT by using the time of the slot BT. Slots BT and DT are operated by a second local oscillator 28 and a synthesizer circuit 35. And also, at the time of receiving slots AR-DR, the first local oscillator 27 and the second local oscillator 28 are alternately switched, and the signal of the prescribed frequency is transmitted to a first intermediate frequency converter 5 for reception by the switching means 29.