Spectrum of the amplitude-modulated wave is observed by a radio frequency spectrum analyzer and amplitude values of every spectrum are recorded at the upper sideband or lower sideband.

用射频频谱分析仪观测一个已调波的频谱成分，记录上边带或下边带中各条谱线的幅度值，从而可以根据有关算式计算出调制信号（音频信号）的失真度。

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Three features parameters derived from the instantaneous amplitude, instantaneous phase, instantaneous frequency and power spectrum of analogue modulated signals are presented in this article.

首先介绍从信号幅度、相位、频率及功率谱等特性中提取的三种特征参数，应用这三种参数采用人工神经网络对模拟调制信号进行了识别。

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The spectrum of amplitude modulated signal are two half magnitude spectrums of base band signal positive and negative shifted by a carrier or R. F. frequency.

调幅讯号之频谱为一半强度基频讯号之频谱分别正负位移一射频或载波之频率。

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