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The redshifted 21 cm line, arising from neutral hydrogen, offers a unique probe into the intergalactic medium and the first stars and galaxies formed in the early universe. However, detecting this signal is a challenging task because of…

Instrumentation and Methods for Astrophysics · Physics 2025-10-09 Shijie Sun , Jiaqin Xu , Minquan Zhou , Shenzhe Xu , Fengquan Wu , Haoran Zhang , Juyong Zhang , Bin Ma , Zhaohui Shang , Xuelei Chen

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

We are developing the Precision Array for Probing the Epoch of Reionization (PAPER) to detect 21cm emission from the early Universe, when the first stars and galaxies were forming. We describe the overall experiment strategy and…

A prototype 425-850 MHz Radio-Frequency-over-Fiber (RFoF) link for the Canadian Hydrogen Intensity Mapping Experiment (CHIME) is presented. The design is based on a directly modulated Fabry-Perot (FP) laser, operating at ambient…

Instrumentation and Methods for Astrophysics · Physics 2015-06-17 Juan Mena , Kevin Bandura , Jean-Francois Cliche , Matt Dobbs , Adam Gilbert , Qing Yang Tang

The behaviour of fast radio bursts (FRBs) at radio frequencies <400 MHz is not well understood due to very few detections, with only two known sources detected below 300 MHz. Characterising low-frequency emission of FRBs is vital for…

High Energy Astrophysical Phenomena · Physics 2025-12-03 Pragya Chawla , Akshatha Gopinath , Ninisha Manaswini , Cees Bassa , Jason Hessels , Vlad Kondratiev , Daniele Michilli , Ziggy Pleunis

Radio frequency interference (RFI) poses a growing challenge to satellite communications, particularly in uplink channels of Low Earth Orbit (LEO) systems, due to increasing spectrum congestion and uncertainty in the location of terrestrial…

Signal Processing · Electrical Eng. & Systems 2025-10-02 Fernando Moya Caceres , Akram Al-Hourani , Saman Atapattu , Kandeepan Sithamparanathan

Low-frequency observatories are currently being constructed with the goal of detecting redshifted 21cm emission from the epoch of reionization. These observatories will also be able to detect intensity fluctuations in the cumulative 21cm…

Astrophysics · Physics 2015-05-13 Stuart Wyithe , Abraham Loeb , Paul Geil

The designs of the first generation of cosmological 21-cm observatories are split between single dipole experiments which integrate over a large patch of sky in order to find the global (spectral) signature of reionization, and…

Cosmology and Nongalactic Astrophysics · Physics 2011-05-23 Jonathan M. Bittner , Abraham Loeb

Radio astronomy observations at frequencies below 10~MHz could provide valuable science, such as measuring the cosmic dark age signal in the redshifted 21~cm hydrogen absorption line, detecting exoplanetary auroral emissions which lead to…

Instrumentation and Methods for Astrophysics · Physics 2025-08-26 Ekaterina Kononov , Mary Knapp

We propose a novel approach for mitigating radio frequency interference (RFI) signals in radio data using the latest advances in deep learning. We employ a special type of Convolutional Neural Network, the U-Net, that enables the…

Instrumentation and Methods for Astrophysics · Physics 2017-01-16 Joel Akeret , Chihway Chang , Aurelien Lucchi , Alexandre Refregier

SETI@home is a radio Search for Extraterrestrial Intelligence (SETI) project that looks for technosignatures in data recorded at the Arecibo Observatory. The data were collected over a period of 14 years and cover almost the entire sky…

Instrumentation and Methods for Astrophysics · Physics 2025-07-25 David P. Anderson , Eric J. Korpela , Dan Werthimer , Jeff Cobb , Bruce Allen

Radio wave scattering can cause severe reductions in detection sensitivity for surveys of Galactic and extragalactic fast ($\sim$ms duration) transients. While Galactic sources like pulsars undergo scattering in the Milky Way interstellar…

Astrophysics of Galaxies · Physics 2022-08-03 S. K. Ocker , J. M. Cordes , S. Chatterjee , M. R. Gorsuch

Radial-velocity (RV) signals induce RV variations an order of magnitude larger than the signal created by the orbit of Earth-twins, thus preventing their detection. The goal of this paper is to compare the efficiency of the different…

Measurement of the global 21-cm signal during Cosmic Dawn (CD) and the Epoch of Reionization (EoR) is made difficult by bright foreground emission which is 2-5 orders of magnitude larger than the expected signal. Fitting for a…

Cosmology and Nongalactic Astrophysics · Physics 2024-02-20 Michael Pagano , Peter Sims , Adrian Liu , Dominic Anstey , Will Handley , Eloy De Lera Acedo

(Abridged) Noise considerations for experiments that aim to statistically estimate the 21 cm signal from high redshift neutral hydrogen during the Epoch of Reionisation (EoR) using interferometric data are typically computed assuming a…

Cosmology and Nongalactic Astrophysics · Physics 2015-06-19 Cathryn M. Trott

Radio interferometric observations are less susceptible to radio frequency interference (RFI) than single dish observations. This is primarily due to : (1)fringe-frequency averaging at the correlator output and (2) bandwidth decorrelation…

Astrophysics · Physics 2007-05-23 D. Anish Roshi , R. A. Perley

Detection of the global redshifted 21-cm signal is an excellent means of deciphering the physical processes during the Dark Ages and subsequent Epoch of Reionization (EoR). However, detection of this faint monopole is challenging due to…

Instrumentation and Methods for Astrophysics · Physics 2015-12-16 Saurabh Singh , Ravi Subrahmanyan , N. Udaya Shankar , A. Raghunathan

LOFAR (Low Frequency Array) is an innovative radio telescope optimized for the frequency range 30-240 MHz. The telescope is realized as a phased aperture array without any moving parts. Digital beam forming allows the telescope to point to…

This paper aims to reconstruct the internal structure of a two-dimensional test object via numerically simulated full-wave time domain radar tomography with the presence of wavelength-induced (WI) uncertainties, following from a complex…

Earth and Planetary Astrophysics · Physics 2022-07-06 Yusuf Oluwatoki Yusuf , Astrid Dufaure , Liisa-Ida Sorsa , Christelle Eyraud , Sampsa Pursiainen

The development of new phased array systems in radio astronomy, as the low frequency array (LOFAR) and the square kilometre array (SKA), formed of a large number of small and flexible elementary antennas, has led to significant challenges.…