Editing Time–frequency representation (section)

{{see also|Time–frequency analysis}}
A '''time–frequency representation''' ('''TFR''') is a view of a [[signal processing|signal]] (taken to be a function of time) represented over both time and [[frequency]].<ref>E. Sejdić, I. Djurović, J. Jiang, "Time-frequency feature representation using energy concentration: An overview of recent advances," Digital Signal Processing, vol. 19, no. 1, pp. 153-183, January 2009.</ref> [[Time–frequency analysis]] means analysis into the time–frequency domain provided by a TFR. This is achieved by using a formulation often called "Time–Frequency Distribution", abbreviated as TFD.

TFRs are often complex-valued fields over time and frequency, where the [[absolute value#Complex numbers|modulus]] of the field represents either amplitude or "energy density" (the concentration of the [[root mean square]] over time and frequency), and the [[argument (complex analysis)|argument]] of the field represents phase.