Covariant Time Frequency Representations Through Unitary Equivalence
Baraniuk, Richard G.
We propose a straightforward characterization of all quadratic time-frequency representations covariant to an important class of unitary signal transforms (namely, those having two continuous-valued parameters and an underlying group structure). Thanks to a fundamental theorem from the theory of Lie groups, we can describe these representations simply in terms of unitary transformations of the well-known Cohen's and affine classes.
time-frequency representations; Time Frequency and Spectral Analysis; time-frequency representations