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We investigate the benefits and challenges of utilizing the frequency information in differential equation identification. Solving differential equations and Fourier analysis are closely related, yet there is limited work in exploring this…

Numerical Analysis · Mathematics 2023-11-29 Mengyi Tang , Hao Liu , Wenjing Liao , Sung Ha Kang

We have compared the respective efficiencies of off-axis and phase-shifting holography in terms of noise and aliases removal. The comparison is made by analyzing holograms of an USAF target backlit with laser illumination, recorded with a…

Optics · Physics 2009-11-13 Michel Gross , Michael Atlan , Emilie Absil

Optical interference is not only a fundamental phenomenon that has enabled new theories of light to be derived but it has also been used in interferometry for the measurement of small displacements, refractive index changes and surface…

Optics · Physics 2021-10-28 Chen Yang , Zhi-Yuan Zhou , Yan Li , Shi-Kai Liu , Zheng Ge , Guang-Can Guo , Bao-Sen Shi

Context: New generation low-frequency telescopes are exploring a new parameter space in terms of depth and resolution. The data taken with these interferometers, for example with the LOw Frequency ARray (LOFAR), are often calibrated in a…

When taking images against strong light sources, the resulting images often contain heterogeneous flare artifacts. These artifacts can importantly affect image visual quality and downstream computer vision tasks. While collecting real data…

Image and Video Processing · Electrical Eng. & Systems 2023-09-01 Yuyan Zhou , Dong Liang , Songcan Chen , Sheng-Jun Huang , Shuo Yang , Chongyi Li

Radio spectroscopy provides a unique inspection perspective for solar and space weather research, which can reveal the plasma and energetic electron information in the solar corona and inner heliosphere. However, Radio-Frequency…

Solar and Stellar Astrophysics · Physics 2023-02-22 Peijin Zhang , André R. Offringa , Pietro Zucca , Kamen Kozarev , Mattia Mancini

We present a pattern-recognition based approach to the problem of removal of polarized fringes from spectro-polarimetric data. We demonstrate that 2D Principal Component Analysis can be trained on a given spectro-polarimetric map in order…

Instrumentation and Methods for Astrophysics · Physics 2015-06-11 R. Casini , P. G. Judge , T. A. Schad

Next-generation spectroscopic surveys will map the large-scale structure of the observable universe, using emission line galaxies as tracers. While each survey will map the sky with a specific emission line, interloping emission lines can…

Cosmology and Nongalactic Astrophysics · Physics 2016-04-20 Anthony R. Pullen , Christopher M. Hirata , Olivier Dore , Alvise Raccanelli

Radio astronomy is facing critical challenges due to an ever-increasing human-made signal density filling up the radio spectrum. With the rise of satellites, mobile networks, and other wireless technologies, radio telescopes are struggling…

Instrumentation and Methods for Astrophysics · Physics 2025-12-24 Kaushal D. Buch , Thushara Gunaratne , Gregory Hellbourg , Cedric Viou , Benjamin Winkel

Context. Narrow-band interference filters can be tuned toward shorter wavelengths by tilting them from the perpendicular to the optical axis. This can be used as a cheap alternative to real tunable filters, such as Fabry-P\'erot…

Instrumentation and Methods for Astrophysics · Physics 2011-08-31 Mats G. Löfdahl , Vasco M. J. Henriques , Dan Kiselman

One of the types of signals for which the LIGO interferometric gravitational wave detectors will search is a stochastic background of gravitational radiation. We review the technique of searching for a background using the…

Several post-detection approaches to the mitigation of radio-frequency interference (RFI) are compared by applying them to the strong RFI from the Iridium satellites. These provide estimates for the desired signal in the presence of RFI, by…

Instrumentation and Methods for Astrophysics · Physics 2019-04-02 Avinash A. Deshpande , B. M. Lewis

A technique is described for removing interference from a signal of interest ("channel 1") which is one of a set of N time-domain instrumental signals ("channels 1 to N"). We assume that channel 1 is a linear combination of "true" signal…

General Relativity and Quantum Cosmology · Physics 2007-05-23 Bruce Allen , Wensheng Hua , Adrian Ottewill

Radio Frequency Interference (RFI) is emitted from various sources, terrestrial or orbital, and create a nuisance for ground-based 21cm experiments. In particular, single-dish 21cm intensity mapping experiments will be highly susceptible to…

I discuss approaches to optimally remove noise from images. A generalization of Wiener filtering to Non-Gaussian distributions and wavelets is described, as well as an approach to measure the errors in the reconstructed images. We argue…

Astrophysics · Physics 2009-10-31 Ue-Li Pen

As radio telescopes become more sensitive, the damaging effects of radio frequency interference (RFI) become more apparent. Near radio telescope arrays, RFI sources are often easily removed or replaced; the challenge lies in identifying…

Instrumentation and Methods for Astrophysics · Physics 2018-08-01 Daniel Czech , Amit Mishra , Michael Inggs

Numerous fields of nonlinear physics, very different in nature, produce signals and images, that share the common feature of being essentially constituted of piecewise homogeneous phases. Analyzing signals and images from corresponding…

Data Analysis, Statistics and Probability · Physics 2020-06-17 Barbara Pascal , Nelly Pustelnik , Patrice Abry , Jean-Christophe Géminard , Valérie Vidal

We introduce the cross spectrum based FRB (Fast Radio Burst) search method for VLBI observation. This method optimizes the fringe fitting scheme in geodetic VLBI data post processing, which fully utilizes the cross spectrum fringe phase…

Instrumentation and Methods for Astrophysics · Physics 2018-02-06 Lei Liu , Fengxian Tong , Weimin Zheng , Juan Zhang , Li Tong

In our work, we examine, for the first time, the possibility of fast and efficient source localization directly from the uvobservations, omitting the recovering of the dirty or clean images. We propose a deep neural network-based framework…

Instrumentation and Methods for Astrophysics · Physics 2023-06-21 O. Taran , O. Bait , M. Dessauges-Zavadsky , T. Holotyak , D. Schaerer , S. Voloshynovskiy

We describe a new technique for removing troublesome interference from external coherent signals present in the gravitational wave spectrum. The method works when the interference is present in many harmonics, as long as they remain…

General Relativity and Quantum Cosmology · Physics 2009-12-30 Alicia M. Sintes , Bernard F. Schutz
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