## Beyond time-frequency analysis: Energy densities in one and many dimensions (1998)

by
Richard G. Baraniuk

Citations: | 16 - 4 self |

### BibTeX

@MISC{Baraniuk98beyondtime-frequency,

author = {Richard G. Baraniuk},

title = {Beyond time-frequency analysis: Energy densities in one and many dimensions},

year = {1998}

}

### Years of Citing Articles

### OpenURL

### Abstract

Given a unitary operator A representing a physical quantity of interest, we employ concepts from group representation theory to define two natural signal energy densities for A. The first is invariant to A and proves useful when the effect of A is to be ignored; the second is covariant to A and measures the “A ” content of signals. We also consider joint densities for multiple operators and, in the process, provide an alternative interpretation of Cohen’s general construction for joint distributions of arbitrary variables.