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We consider the recovery of square-integrable signals from discrete, equidistant samples of their Gabor transform magnitude and show that, in general, signals can not be recovered from such samples. In particular, we show that for any…

Functional Analysis · Mathematics 2022-01-03 Rima Alaifari , Matthias Wellershoff

Gabor phase retrieval is the problem of reconstructing a signal from only the magnitudes of its Gabor transform. Previous findings suggest a possible link between unique solvability of the discrete problem (recovery from measurements on a…

Functional Analysis · Mathematics 2025-05-07 Rima Alaifari , Francesca Bartolucci , Stefan Steinerberger , Matthias Wellershoff

We establish novel uniqueness results for the Gabor phase retrieval problem: if $\mathcal{G} : L^2(\mathbb{R}) \to L^2(\mathbb{R}^2)$ denotes the Gabor transform then every $f \in L^4[-\tfrac{c}{2},\tfrac{c}{2}]$ is determined up to a…

Functional Analysis · Mathematics 2022-09-16 Philipp Grohs , Lukas Liehr

Sampled Gabor phase retrieval - the problem of recovering a square-integrable signal from the magnitude of its Gabor transform sampled on a lattice - is a fundamental problem in signal processing, with important applications in areas such…

Functional Analysis · Mathematics 2025-05-07 Rima Alaifari , Francesca Bartolucci , Matthias Wellershoff

It was recently shown that functions in $L^4([-B,B])$ can be uniquely recovered up to a global phase factor from the absolute values of their Gabor transforms sampled on a rectangular lattice. We prove that this remains true if one replaces…

Functional Analysis · Mathematics 2023-08-29 Matthias Wellershoff

Gabor phase retrieval stands for recovering a square integrable function up to a global phase from absolute values of its Gabor transform. In this paper, we study Gabor phase retrieval from discrete samples. We consider three types of…

Classical Analysis and ODEs · Mathematics 2025-12-02 Ting Chen , Hanwen Lu , Wenchang Sun

We characterise all pairs of finite order entire functions whose magnitudes agree on two arbitrary lines in the complex plane by means of the Hadamard factorisation theorem. Building on this, we also characterise all pairs of second order…

Complex Variables · Mathematics 2025-05-07 Matthias Wellershoff

We consider the problem of phase retrieval from magnitudes of short-time Fourier transform (STFT) measurements. It is well-known that signals are uniquely determined (up to global phase) by their STFT magnitude when the underlying window…

Functional Analysis · Mathematics 2021-01-07 Rima Alaifari , Matthias Wellershoff

We study the problem of recovering a function of the form $f(x) = \sum _{k\in \mathbb{Z} } c_k e^{-(x-k)^2}$ from its phaseless samples $|f(\lambda )|$ on some arbitrary countable set $\Lambda \subseteq \mathbb{R} $. For real-valued…

Complex Variables · Mathematics 2023-04-18 Karlheinz Gröchenig

We study the determination of a holomorphic function from its absolute value. Given a parameter $\theta \in \mathbb{R}$, we derive the following characterization of uniqueness in terms of rigidity of a set $\Lambda \subseteq \mathbb{R}$: if…

Complex Variables · Mathematics 2025-05-06 Lukas Liehr

Short-time Fourier transform (STFT) phase retrieval refers to the reconstruction of a function $f$ from its spectrogram, i.e., the magnitudes of its short-time Fourier transform $V_gf$ with window function $g$. While it is known that for…

Functional Analysis · Mathematics 2024-11-21 Philipp Grohs , Lukas Liehr , Martin Rathmair

We show that bandlimited signals can be uniquely recovered (up to a constant global phase factor) from Gabor transform magnitudes sampled at twice the Nyquist rate in two frequency bins.

Functional Analysis · Mathematics 2026-04-10 Matthias Wellershoff

Phase retrieval refers to the problem of recovering some signal (which is often modelled as an element of a Hilbert space) from phaseless measurements. It has been shown that in the deterministic setting phase retrieval from frame…

Numerical Analysis · Mathematics 2021-11-11 Rima Alaifari , Matthias Wellershoff

We study the recovery of square-integrable signals from the absolute values of their wavelet transforms, also called wavelet phase retrieval. We present a new uniqueness result for wavelet phase retrieval. To be precise, we show that any…

Functional Analysis · Mathematics 2026-04-10 Rima Alaifari , Francesca Bartolucci , Matthias Wellershoff

Conjugate phase retrieval considers the recovery of a function, up to a unimodular constant and conjugation, from its phaseless measurements. In this paper, we explore the conjugate phase retrieval in a shift-invariant space generated by a…

Functional Analysis · Mathematics 2026-03-04 Yang Chen , Cheng Cheng

The reconstruction of a function from its spectrogram (i.e., the absolute value of its short-time Fourier transform (STFT)) arises as a key problem in several important applications, including coherent diffraction imaging and audio…

Functional Analysis · Mathematics 2023-10-02 Philipp Grohs , Lukas Liehr

We study the uniqueness problem in short-time Fourier transform phase retrieval by exploring a connection to the completeness problem of discrete translates. Specifically, we prove that functions in $L^2(K)$ with $K \subseteq \mathbb{R}^d$…

Functional Analysis · Mathematics 2025-05-01 Philipp Grohs , Lukas Liehr , Irina Shafkulovska

Compressed sensing investigates the recovery of sparse signals from linear measurements. But often, in a wide range of applications, one is given only the absolute values (squared) of the linear measurements. Recovering such signals (not…

Functional Analysis · Mathematics 2015-09-29 Irena Bojarovska , Axel Flinth

In this paper we consider the following problem of phase retrieval: Given a collection of real-valued band-limited functions $\{\psi_{\lambda}\}_{\lambda\in \Lambda}\subset L^2(\mathbb{R}^d)$ that constitutes a semi-discrete frame, we ask…

Functional Analysis · Mathematics 2016-09-07 Rima Alaifari , Ingrid Daubechies , Philipp Grohs , Gaurav Thakur

A conjecture is proposed concerning the recovery of a discrete magnitude spectrum through a nonlinear transformation involving the Newman's phase sequence. Given a discrete magnitude spectrum sampled from a continuous function, consider the…

Optimization and Control · Mathematics 2025-09-16 Shravan Mohan
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