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日本NEC公司最新研制的800系列大容量数字微波无线电(DM R)系统可在每个射频载波上传输2个或3个DS3信号。为有效利用无线电频谱,该系统采用了64态正交幅度调制(64QAM)。其中满足FCC标准的3个系统为:
Japan’s NEC recently developed 800 series high-capacity digital microwave radio (DM R) system can transmit 2 or 3 DS3 signals on each RF carrier. The system uses 64 quadrature amplitude modulation (64QAM) to effectively utilize the radio spectrum. The three systems that meet the FCC standards are: