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1.前言数字微波系统自1969年首次投入使用以来,世界各国都在积极开发、使用。其根本技术主要是通过调制信号的多值化来增大传输容量、提高频谱利用效率。在此期间,调制形式已从4PSK发展到8PSK,16QAM,目前研究重点又转到64QAM、256QAM方面。本文,就采用64/256QAM调制的系统及实现这些系统所需要的各种技术,介绍它的目前水平与发展趋势。
1. Introduction Since the first digital microwave system was put into use in 1969, all countries in the world are actively developing and using it. The fundamental technology is to increase the transmission capacity and improve the efficiency of spectrum utilization through the multi-valued modulation signals. During this period, the modulation form has been developed from 4PSK to 8PSK, 16QAM, the current research focus has shifted to 64QAM, 256QAM aspects. This article describes the current levels and trends in systems that use 64 / 256QAM modulation and the various technologies required to implement these systems.