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Time-frequency representations stemmed in 1932 with the introduction of the Wigner distribution. For most of the 20th century, research in this area primarily focused on defining joint probability distributions for position and momentum in…

Analysis of PDEs · Mathematics 2026-01-13 Gianluca Giacchi

In the last twenty years modulation spaces, introduced by H. G. Feichtinger in 1983, have been successfully addressed to the study of signal analysis, PDE's, pseudodifferential operators, quantum mechanics, by hundreds of contributions. In…

Functional Analysis · Mathematics 2023-02-13 Elena Cordero , Luigi Rodino

We study the phase-space concentration of the so-called generalized metaplectic operators whose main examples are Schr\"odinger equations with bounded perturbations. To reach this goal, we perform a so-called $\mathcal{A}$-Wigner analysis…

Analysis of PDEs · Mathematics 2022-09-15 Elena Cordero , Gianluca Giacchi , Luigi Rodino

We perform Wigner analysis of linear operators. Namely, the standard time-frequency representation \emph{Short-time Fourier Transform} (STFT) is replaced by the $\mathcal{A}$-\emph{Wigner distribution} defined by $W_{\mathcal A}…

Analysis of PDEs · Mathematics 2021-08-10 Elena Cordero , Luigi Rodino

Metaplectic Wigner distributions are joint time-frequency representations that are parametrized by a symplectic matrix and generalize the short-time Fourier transform and the Wigner distribution. We investigate the question which…

Functional Analysis · Mathematics 2024-05-21 Karlheinz Gröchenig , Irina Shafkulovska

Metaplectic Wigner distributions generalize the most popular time-frequency representations, such as the short-time Fourier transform (STFT) and $\tau$-Wigner distributions, using metaplectic operators. However, in order for a metaplectic…

Analysis of PDEs · Mathematics 2024-03-27 Elena Cordero , Gianluca Giacchi

We present a different symplectic point of view in the definition of weighted modulation spaces $M^{p,q}_m(\mathbb{R}^d)$ and weighted Wiener amalgam spaces $W(\mathcal{F} L^p_{m_1},L^q_{m_2})(\mathbb{R}^d)$. All of the classical…

Analysis of PDEs · Mathematics 2024-01-18 Elena Cordero , Gianluca Giacchi

Metaplectic Wigner distributions were recently investigated as natural generalizations of the classical Wigner distribution, and provide a wide class of time-frequency representations that exploits the structure of the symplectic group.…

Analysis of PDEs · Mathematics 2023-01-24 Gianluca Giacchi

We introduce new frames, called \textit{metaplectic Gabor frames}, as natural generalizations of Gabor frames in the framework of metaplectic Wigner distributions. Namely, we develop the theory of metaplectic atoms in a full-general setting…

Analysis of PDEs · Mathematics 2024-01-18 Elena Cordero , Gianluca Giacchi

The Wigner distribution is a milestone of Time-frequency Analysis. In order to cope with its drawbacks while preserving the desirable features that made it so popular, several kind of modifications have been proposed. This contributions…

Functional Analysis · Mathematics 2020-08-05 Elena Cordero , S. Ivan Trapasso

Time-frequency localization operators, originally introduced by Daubechies (1988), provide a framework for localizing signals in the phase space and have become a central tool in time-frequency analysis. In this paper we introduce and study…

Functional Analysis · Mathematics 2025-11-04 Elena Cordero , Edoardo Pucci

The conventional Cohen's distribution can't meet the requirement of additive noises jamming signals high-performance denoising under the condition of low signal-to-noise ratio, it is necessary to integrate the metaplectic transform for…

Signal Processing · Electrical Eng. & Systems 2024-08-09 Manjun Cui , Zhichao Zhang , Jie Han , Yunjie Chen , Chunzheng Cao

We develop a systematic analysis of the metaplectic semigroup $\mathrm{Mp}_+(d,\mathbb{C})$ associated with positive complex symplectic matrices, a notion introduced almost simultaneously and independently by H\"ormander, Brunet, Kramer,…

Analysis of PDEs · Mathematics 2026-05-12 Gianluca Giacchi , Luigi Rodino , Davide Tramontana

Time-frequency representations such as the spectrogram are commonly used to analyze signals having a time-varying distribution of spectral energy, but the spectrogram is constrained by an unfortunate tradeoff between resolution in time and…

Sound · Computer Science 2009-03-19 Kelly R. Fitz , Sean A. Fulop

We characterize all time-frequency representations that satisfy a general covariance property: any weak*-continuous bilinear mapping that intertwines time-frequency shifts on the configuration space with time-frequency shifts on phase space…

Functional Analysis · Mathematics 2025-05-13 Karlheinz Gröchenig , Irina Shafkulovska

We present a new approach, based on graphon theory, to finding the limiting spectral distributions of general Wigner-type matrices. This approach determines the moments of the limiting measures and the equations of their Stieltjes…

Probability · Mathematics 2020-08-11 Yizhe Zhu

We study a class of quadratic time-frequency representations that, roughly speaking, are obtained by linear perturbations of the Wigner transform. They satisfy Moyal's formula by default and share many other properties with the Wigner…

Functional Analysis · Mathematics 2020-04-06 Dominik Bayer , Elena Cordero , Karlheinz Gröchenig , S. Ivan Trapasso

The problem of identifying and reconstructing operators from a diagonal of the Gabor matrix is considered. The framework of Quantum Time--Frequency Analysis is used, wherein this problem is equivalent to the discretisation of the diagonal…

Functional Analysis · Mathematics 2024-11-05 Henry McNulty

We show that the cross Wigner function can be written in the form $W(\psi, \phi)= \hat S (\psi \otimes \overline{\hat\phi})$ where ${\hat\phi}$ is the Fourier transform of $\phi$ and $\hat S$ is a metaplectic operator that projects onto a…

Mathematical Physics · Physics 2014-01-16 Nuno Costa Dias , Maurice A. de Gosson , João Nuno Prata

In this note we exhibit recent advances in signal analysis via time-frequency distributions. New members of the Cohen class, generalizing the Wigner distribution, reveal to be effective in damping artefacts of some signals. We will survey…

Functional Analysis · Mathematics 2019-12-25 Elena Cordero , Maurice de Gosson , Monika Dörfler , Fabio Nicola
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