Covariant time-frequency representations through unitary equivalence

R.G. Baraniuk
1996 IEEE Signal Processing Letters  
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.
doi:10.1109/97.481161 fatcat:vwxu7em2qjcrxclxjf2xisicf4