| 摘要 |
Up and down signal levels in a wireless base station and a forward base station can be automatically adjusted into predetermined levels respectively with a simple configuration. In an interface portion 12 , a pilot signal P of a predetermined level is generated by a pilot signal generator 120 , and multiplexed with a down transmission signal 111 from a wireless base station 11 by a multiplexer 121 . The multiplexed signal is amplified with a constant gain by a down signal amplifier 122 , then converted into a down optical signal by an electro-optic converter 123 , wavelength-multiplexed by an optical multi/demultiplexer 124 , sent out to an optical fiber 15 , and transmitted to a forward base station 13 . In the forward base station 13 , the down optical signal wavelength-demultiplexed by an optical multi/demultiplexer 124 is converted into a down electric signal by an opto-electric converter 125 , and the pilot signal P is demultiplexed by a demultiplexer 133 . A gain control unit 130 detects an absolute level of the pilot signal P, and outputs a gain control signal G 1 to set the level value at a predetermined rated value. A down signal gain variable amplifier 134 and an up signal gain variable amplifier 136 amplify the down transmission signal and the up reception signal respectively with a gain controlled by the gain control signal G 1.
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