##  [Power Spectral Density](/power-spectral-density) 

  ##  [Power Spectral Density](https://engineering.quantumdictionary.io/power-spectral-density-0) 

  

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**Engineering & Applied Technologies Dictionary**

 







 

 

 

 



 

 

 

 

Definition

A frequency‑domain function that describes how the power or variance of a time‑series signal is distributed across frequency; for a wide‑sense stationary stochastic process the (auto)power spectral density S_x(f) is the Fourier transform of the autocorrelation function and has units of power per hertz (e.g., W·Hz⁻¹).