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提出了应用于光纤无线通信系统中一种改进的双边带调制产生光毫米波方案。在中心站采用强度调制将射频信号调制到光载波上产生一个双边带信号,滤掉中心载波后,利用光交叉复用器把双边带信号的上下边带模分开,将数据速率为2.5Gbit/s的基带信号调制到下边带模后,再与未调信号耦合后产生光毫米波,然后通过单模光纤传输至基站,在基站经过光电转换后产生电毫米波信号。从理论上对该毫米波的色散特性进行了分析,发现毫米波的接收功率不会周期的衰减。同时通过实验研究表明,下行链路信号通过光纤能传输50km而不需要色散补偿,功率代价小于1dBm。因此,该方法产生的光毫米波能有效克服光纤色散引起的信号时延而导致的基带信号退化,适合于远距离传输。
An improved double-sideband modulated optical millimeter-wave scheme is proposed for optical fiber wireless communication systems. The center station uses the intensity modulation to modulate the RF signal to the optical carrier to generate a double-sideband signal. After filtering out the center carrier, the optical cross-multiplexer separates the upper and lower sideband signals of the double sideband signal, and the data rate is 2.5Gbit / s baseband signal modulated to the lower band mode, coupled with the unregulated signal generated after the optical millimeter wave, and then transmitted to the base station through a single-mode optical fiber in the base station after photoelectric conversion to generate electrical millimeter wave signal. The chromatic dispersion characteristics of the millimeter wave are theoretically analyzed, and it is found that the received power of the millimeter wave does not periodically decay. At the same time, experimental studies show that the downlink signal can transmit 50km through optical fiber without dispersion compensation, the power cost is less than 1dBm. Therefore, the optical millimeter wave generated by the method can effectively overcome the signal delay caused by the dispersion of the optical fiber and degrade the baseband signal, and is suitable for long-distance transmission.