Power spectrum

The power spectrum of a signal is the power or more simply the energy of the signal at each frequency that it contains. It can also be considered as the range or spectra of energy or power of the given signal derived from the signals' range of frequencies. For example, white noise, which contains all frequencies at the same power, has a flat power spectrum. The power spectrum of the sound of the bottom key on a piano would have a high value at the frequency corresponding to its note, and low values elsewhere.

Power Spectrum Media

• 

  The spectral density of a fluorescent light as a function of optical wavelength shows peaks at atomic transitions, indicated by the numbered arrows.

• 

  The voice waveform over time (left) has a broad audio power spectrum (right).

• 

  The power spectrum of the measured cosmic microwave background radiation temperature anisotropy in terms of the angular scale. The solid line is a theoretical model, for comparison.

• 

  Spectrogram of an FM radio signal with frequency on the horizontal axis and time increasing upwards on the vertical axis.