The hyperbolic class of quadratic time-frequency representations-part ii: subclasses, intersection with the affine and power classes, regularity, and unitarity

Franz Hlawatsch, Antonia Papandreou-Suppappola, G. Paye Boudreaux-Bartels, F. Hlawatsch

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18 Scopus citations


Part I of this paper introduced the hyperbolic class (HC) of quadratic/bilinear time-frequency representations (QTFR's) as a new framework for constant-Q time-frequency analysis. The present Part II defines and studies the following four subclasses of the HC: The localized-kernel subclass of the HC is related to a timefrequency concentration property of QTFR's. It is analogous to the localized-kernel subclass of the affine QTFR class. The affine subclass of the HC (affine HC) consists of all HC QTFR's that satisfy the conventional time-shift covariance property. It forms the intersection of the HC with the affine QTFR class. The power subclasses of the HC consist of all HC QTFR's that satisfy a "power time-shift" covariance property. They form the intersection of the HC with the recently introduced power classes. The power-warp subclass of the HC consists of all HC QTFR's that satisfy a covariance to power-law frequency warpings. It is the HC counterpart of the shift-scale covariant subclass of Cohen's class. All of these subclasses are characterized by 1-D kernel functions. It is shown that the affine HC is contained in both the localizedkernel hyperbolic subclass and the localized-kernel affine subclass and that any affine HC QTFR can be derived from the Bertrand unitary P0 -distribution by a convolution. We furthermore consider the properties of regularity (invert ibility of a QTFR) and unitarity (preservation of inner products, Moyal's formula) in the HC. The calculus of inverse kernels is developed, and important implications of regularity and unitarity are summarized. The results comprise a general method for least-squares signal synthesis and new relations for the AltesMarinovich Q-distribution.

Original languageEnglish (US)
Pages (from-to)303-315
Number of pages13
JournalIEEE Transactions on Signal Processing
Issue number2
StatePublished - Jan 1 1997
Externally publishedYes


ASJC Scopus subject areas

  • Signal Processing
  • Electrical and Electronic Engineering

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