功率谱是功率谱密度函数的简称，它定义为单位频带内的信号功率。它表示了信号功率随着频率的变化情况，即信号功率在频域的分布状况。-Spectral analysis or Spectrum analysis is analysis in terms of a spectrum of frequencies or related quantities such as energies, eigenvalues, etc. In specific areas it may refer to:



Spectroscopy in chemistry and physics, a method of analyzing the properties of matter　their electromagnetic interactions

Spectral estimation, in statistics and signal processing, an algorithm that estimates the strength of different frequency components (the power spectrum) of a time-domain signal. This may also be called frequency domain analysis

Spectrum analyzer, a hardware device that measures the magnitude of an input signal versus frequency within the full frequency range of the instrument

Spectral theory, in mathematics, a theory that extends eigenvalues and eigenvectors to linear operators on Hilbert space, and more generally to the elements of a Banach algebra

In nuclear and particle physics, gamma spectroscopy, and high-energy astronomy, the analysis of the output of a pulse height analyze