| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide a communication system or the like in which the costs of a radio base station can be reduced, the frequency of a modulated signal transmitted from the radio base station can be stabilized and a phase noise can be reduced. <P>SOLUTION: An oscillator 12 installed in a radio base station 2 is irradiated with an optical signal of a strength modulated in a frequency approximate to the oscillation frequency of said oscillator, and the phase noise and the frequency fluctuation of a radio signal outputted from the oscillator 12 are reduced by a light injection synchronism effect. Besides, the optical signal of a strength modulated in a prescribed frequency is transmitted from a control station 1, and is converted to an electric signal by a photodiode 36 installed in the radio base station. By using the electric signal as a local signal for a mixer 40 installed in the radio base station 2, the costs of the system can be reduced. <P>COPYRIGHT: (C)2003,JPO |
