Injectivity conditions for STFT phase retrieval on $\mathbb{Z}$, $\mathbb{Z}_d$ and $\mathbb{R}^d$

TL;DR

This paper investigates the conditions under which phase retrieval using the short-time Fourier transform is uniquely possible on various groups, providing new characterizations for more general windows beyond the classical ambiguity function condition.

Contribution

It establishes new, comprehensive criteria for phase retrieval with general windows on $ ext{Z}$, $ ext{Z}_d$, and $ ext{R}^d$, expanding beyond the classical ambiguity function condition.

Findings

New characterizations depend mainly on signal support.

Conditions are applicable to a broader class of windows.

The sharpness of results is demonstrated through examples.

Abstract

We study the phase retrieval problem for the short-time Fourier transform on the groups $\mathbb{Z}$, $\mathbb{Z}_d$ and $\mathbb{R}^d$. As is well-known, phase retrieval is possible, once the window's ambiguity function vanishes nowhere. However, there are only few results for windows which don't meet this condition. The goal of this paper is to establish new and complete characterizations for phase retrieval with more general windows and compare them to existing results. For a fixed window, our uniqueness conditions usually only depend on the signal's support and are therefore easily comprehensible. Additionally, we discuss sharpness of both new and existing results by looking at various examples along the way.