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The Fourier spectrum at a fractional period is often examined when extracting features from biological sequences and time series. It reflects the inner information structure of the sequences. A fractional period is not uncommon in time…

Spectral Theory · Mathematics 2017-11-03 Jiasong Wang , Changchuan Yin

Along with AIGC shines in CV and NLP, its potential in the wireless domain has also emerged in recent years. Yet, existing RF-oriented generative solutions are ill-suited for generating high-quality, time-series RF data due to limited…

Machine Learning · Computer Science 2024-04-16 Guoxuan Chi , Zheng Yang , Chenshu Wu , Jingao Xu , Yuchong Gao , Yunhao Liu , Tony Xiao Han

High-concentration time-frequency (TF) representation provides a valuable tool for characterizing multi-component non-stationary signals. In our previous work, we proposed using an instantaneous frequency (IF) equation to sharpen the TF…

Signal Processing · Electrical Eng. & Systems 2023-03-13 Xiangxiang Zhu , Kunde Yang , Zhuosheng Zhang

Time-encoding of continuous-time signals is an alternative sampling paradigm to conventional methods such as Shannon's sampling. In time-encoding, the signal is encoded using a sequence of time instants where an event occurs, and hence fall…

Signal Processing · Electrical Eng. & Systems 2021-09-06 Abijith Jagannath Kamath , Sunil Rudresh , Chandra Sekhar Seelamantula

The long therm behavior of chaotic flows is investigated by means of time dependent frequency analysis. The system under test consists of an electrically conducting fluid, confined between two differentially rotating spheres. The spherical…

Fluid Dynamics · Physics 2021-02-24 Ferran Garcia , Martin Seilmayer , André Giesecke , Frank Stefani

We present a novel family of continuous, linear time-frequency transforms adaptable to a multitude of (nonlinear) frequency scales. Similar to classical time-frequency or time-scale representations, the representation coefficients are…

Functional Analysis · Mathematics 2024-03-20 Nicki Holighaus , Christoph Wiesmeyr , Peter Balazs

We report experimental results of parallel measurement of spectral components of the light. The temporal fluctuations of an optical field mixed with a separate reference are recorded with a high throughput complementary metal oxide…

Optics · Physics 2008-11-26 Michael Atlan , Michel Gross

This work considers uncertainty relations on time frequency distributions from a signal processing viewpoint. An uncertainty relation on the marginalizable time frequency distributions is given. A result from quantum mechanics is used on…

Signal Processing · Electrical Eng. & Systems 2021-04-27 Eren Berk Kama , Mustafa Kuzuoğlu

Resonances are common in wave physics and their full and rigorous characterization is crucial to correctly tailor the response of a system in both time and frequency domains. However, they have been conventionally described by the quality…

Optics · Physics 2025-04-09 Isam Ben Soltane , Nicolas Bonod

This paper presents a time-causal analogue of the Gabor filter, as well as a both time-causal and time-recursive analogue of the Gabor transform, where the proposed time-causal representations obey both temporal scale covariance and a…

Signal Processing · Electrical Eng. & Systems 2025-10-10 Tony Lindeberg

The analysis of signals created by a variety of instruments involves calculating the phase of a sinusoidal type signal. One widely used method to extract this information is through the use of Fourier transforms, but it is known that…

Optics · Physics 2018-11-02 Andrew John Henning , Dawei Tang , Xiangqian , Jiang

Willems' fundamental lemma enables data-driven analysis and control by characterizing an unknown system's behavior directly in terms of measured data. In this work, we extend a recent frequency-domain variant of this result--previously…

Systems and Control · Electrical Eng. & Systems 2025-04-10 T. J. Meijer , M. Wind , V. S. Dolk , W. P. M. H. Heemels

We present a second quantization description of frequency-based continuous variables quantum computation in the subspace of single photons. For this, we define frequency and time operators using the free field Hamiltonian and its Fourier…

Quantum Physics · Physics 2022-06-01 Nicolas Fabre , Camille Nous , Arne Keller , Pérola Milman

This study puts forward a generalization of the short-time Fourier-based Synchrosqueezing Transform using a new local estimate of instantaneous frequency. Such a technique enables not only to achieve a highly concentrated time-frequency…

Signal Processing · Electrical Eng. & Systems 2020-04-21 Duong-Hung Pham , Sylvain Meignen

Neural time-series analysis has traditionally focused on modeling data in the time domain, often with some approaches incorporating equivalent Fourier domain representations as auxiliary spectral features. In this work, we shift the main…

Machine Learning · Computer Science 2024-10-08 Minjung Kim , Yusuke Hioka , Michael Witbrock

A definition of frequency (cycles per unit-time) based on an approximate reconstruction of the phase-space trajectory of an oscillator from a signal is introduced. It is shown to be invariant under linear filtering, and therefore…

Chaotic Dynamics · Physics 2009-11-10 A G Rossberg

Within the expansive domain of optical sciences, achieving the precise characterization of light beams stands as a fundamental pursuit, pivotal for various applications, including telecommunications and imaging technologies. This study…

When a signal is emitted from a source, recorded by an array of transducers, time reversed and re-emitted into the medium, it will refocus approximately on the source location. We analyze the refocusing resolution in a high frequency,…

Disordered Systems and Neural Networks · Physics 2007-05-23 George Papanicolaou , Leonid Ryzhik , Knut Solna

Mobile communication channels are often modeled as linear time-varying filters or, equivalently, as time-frequency integral operators with finite support in time and frequency. Such a characterization inherently assumes the signals are…

Information Theory · Computer Science 2007-07-16 Scott T. Rickard , Radu V. Balan , H. Vincent Poor , Sergio Verdu

This paper investigates inverse source problems for time-dependent electromagnetic waves governed by Maxwell's equations. After applying the Fourier transform with respect to time, the problem leads to a frequency-domain electromagnetic…

Numerical Analysis · Mathematics 2026-03-11 Fenglin Sun , Hongxia Guo