摘要
本文讨论了信号经过傅立叶变换所得频谱的物理意义,其中着重于负频率成分。许多信号与系统的教材中,都认为负频率成分没有物理意义。本文以多方面的实例证明了负频率成分不但具有明确的物理意义,而且有重要的工程应用价值。文章还用Matlab程序演示了如何用几何方法求傅立叶反变换,把集总频谱合成为时域信号,从中也可鲜明地看出负频率成分的意义。
The physical meaning of the frequency spectrum,especially the negative frequency components,obtained from Fourier transform of signals is discussed.Since some textbooks explain the negative frequency as a pure mathematical expression with no physical meaning.Many examples are given in this paper to show that negative frequency not only contains physical meaning,but also has its real applications.A Matlab demo program is developed to show that the IFT is equivalent to the geometrical composition of several rotating vectors representing lumped frequency spectrums.The geometrical meaning of the negative frequency can be clearly recognized from the rotating vectors.
出处
《电气电子教学学报》
2008年第1期29-32,共4页
Journal of Electrical and Electronic Education
关键词
傅立叶变换
频谱
负频率
集总频谱
Fourier transform
frequency spectrum
negative frequency
lumped spectrum
