Time-frequency representations of broad-band signals

The usual time-frequency representations corresponding to the group of time and frequency translations are shown to give rise to time-localization anomalies. Instead, the affine group of clock changes is used as the basic group of signal theory, and the general affine covariant joint distributions are considered. A subclass is singled out by its interesting properties: it reduces to Wigner-Ville´s function when applied to narrowband signals, it gives the spectrum by time integration, and it is time-localized when applied to a time-localized signal