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Ⅰ背景在目前所采用的数据传输系统中,一般需要比每个符号1/2周的Nyguist最小带宽1要宽得多。这是由于以下的两个主要原因所引起的:第一:基带信号频谱在理论最小值之外是逐渐下降的;第二,把基带频谱变换到带通信道所需的调制过程产生附加的边频,而为了使信号能够复原就必须保存这些附加边频。例如,近来提出的残留边带系统为这两种原因的每一种都使用了50％的额外带宽。所以,这种系统
I Background In the currently used data transmission systems, it is generally required to be much wider than the Nyguist minimum bandwidth of one week per symbol. This is due to two main reasons: First, the spectrum of the baseband signal is gradually decayed beyond the theoretical minimum; second, the modulation process required to transform the baseband spectrum to the bandpass channel produces additional edges Frequency, and these additional side frequencies have to be preserved in order for the signal to recover. For example, the recently proposed residual sideband system uses 50% extra bandwidth for each of these two reasons. So, this system