说明：这是单边带调制源码，求消息信号和已调信号的频谱。
This is a single sideband modulation source, for the signal and the signal has been modulated spectrum.
其思路是将信号先通过单边带调制，将较低频率调制到需要的频率范围；然后采用对基带信号的数字预补偿方法来抑制镜像频率和载波泄漏，从而达到应用的目的。
Then we perform digital pre-compensation method, which can be used in the processing of base band signal to reject image frequency and protect carrier leak to meet the application purpose.
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