Riccardo Chiello

University of Oxford

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Alessio Magro

University of Malta

G. Pupillo

Istituto di Radioastronomia di Bologna

Jader Monari

National Institute for Astrophysics

Federico Perini

National Institute for Astrophysics

A. Mattana

National Institute for Astrophysics

G. Comoretto

Arcetri Astrophysical Observatory

Marco Schiaffino

National Institute for Astrophysics

Kristian Zarb Adami

University of Oxford

M. Sokołowski

Curtin University

G. Naldi

Istituto di Radioastronomia di Bologna

Cooperative Institutions

National Institute for Astrophysics

University of Cambridge

Istituto di Radioastronomia di Bologna

Arcetri Astrophysical Observatory

International Centre for Radio Astronomy Research

Curtin University

Osservatorio Astronomico di Cagliari

Osservatorio Astrofisico di Catania

Agenzia Spaziale Italiana

Trieste Astronomical Observatory

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Design and prototyping of the Italian Tile Processing Module (ITPM) 1.6 for the low-frequency aperture array deployment

F. Schillirò M. Alderighi Carolina Belli Simone Chiarucci Riccardo Chiello

A novel version of digital hardware Italian Tile Processing Module (ITPM) 1.6 has been released for the Low-Frequency Aperture Array (LFAA) component of the Square Kilometre Array (SKA). This back-end includes two plugged-in main blocks, as an analog device , the Pre-ADU board, and an Analog to Digital Unit (ADU), a 6U board containing sixteen dual-inputs Analog to Digital Converters and two Field Programmable Gate Array (FPGA) devices, capable of digitizing and processing 32 RF input signals (50-650 MHz). We present the main features of the upgrade of the board compared to previous versions: there are new and high performance components improving processing capability, mechanical changes matching the design of the housing sub-rack and finally a general reduction of the overall power consumption. The ITPM ADU 1.6 version, now in engineering phase together with its sub-rack system, is currently the last prototype before the design of the industrial line for mass production, necessary for the LFAA deployment. Results of system performances will be presented.

Upgrade

Aperture (computer memory)

Gate array

10.1117/12.2562085

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The Digital Signal Processing Platform for the Low Frequency Aperture Array: Preliminary Results on the Data Acquisition Unit

Journal of Astronomical Instrumentation (2017)

G. Naldi A. Mattana S. Pastore M. Alderighi Kristian Zarb Adami

A signal processing hardware platform has been developed for the Low Frequency Aperture Array component of the Square Kilometre Array (SKA). The processing board, called an Analog Digital Unit (ADU), is able to acquire and digitize broadband (up to 500[Formula: see text]MHz bandwidth) radio-frequency streams from 16 dual polarized antennas, channel the data streams and then combine them flexibly as part of a larger beamforming system. It is envisaged that there will be more than 8000 of these signal processing platforms in the first phase of the SKA, so particular attention has been devoted to ensure the design is low-cost and low-power. This paper describes the main features of the data acquisition unit of such a platform and presents preliminary results characterizing its performance.

Array Processing

10.1142/s2251171716410142

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Design of PHAROS2 Phased Array Feed

2018 2nd URSI Atlantic Radio Science Meeting (AT-RASC) (2018)

A. Navarrini Jader Monari A. Scalambra A. Melis R. Concu

We describe the design and architecture of PHAROS2, a cryogenically cooled 4-8 GHz Phased Array Feed (PAF) demonstrator with digital beamformer for radio astronomy application. The instrument will be capable of synthesizing four independent single-polarization beams by combining 24 active elements of an array of Vivaldi antennas. PHAROS2, the upgrade of PHAROS (PHased Arrays for Reflector Observing Systems), features: a) commercial cryogenic LNAs with state-of-the-art performance, b) a "Warm Section" for signal filtering, conditioning and single downconversion to select a ≈ 275 MHz: Intermediate Frequency (IF) bandwidth within the 4-8 GHz Radio Frequency (RF) band, c) an IF signal transportation by analog WDM (Wavelength Division Mutiplexing) fiber-optic link, and d) a FPGA-based Italian Tile Processing Module (iTPM) digital backend. PHAROS2 will be mounted at the primary focus of the 76-m diameter Lovell radio telescope (Jodrell Bank Observatory, UK) for technical and scientific validation.

Phased-array optics

10.23919/ursi-at-rasc.2018.8471305

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Radio Antenna Design for Sky-Averaged 21cm Cosmology Experiments: The REACH Case

Journal of Astronomical Instrumentation (2021)

John Cumner Eloy de Lera Acedo Dirk I. L. de Villiers Dominic Anstey C. I. Kolitsidas

Following the reported detection of an absorption profile associated with the 21[Formula: see text]cm sky-averaged signal from the Cosmic Dawn by the EDGES experiment in 2018, a number of experiments have been set up to verify this result. This paper discusses the design process used for global 21[Formula: see text]cm experiments, focusing specifically on the Radio Experiment for the Analysis of Cosmic Hydrogen (REACH). This experiment will seek to understand and compensate for systematic errors present using detailed modeling and characterization of the instrumentation. Detailed quantitative figures of merit and numerical modeling are used to assist the design process of the REACH dipole antenna (one of the two antenna designs for REACH Phase I). This design process produced a 2.5:1 frequency bandwidth dipole. The aim of this design was to balance spectral smoothness and low impedance reflections with the ability to describe and understand the antenna response to the sky signal to inform the critically important calibration during observation and data analysis.

Skywave

10.1142/s2251171722500015

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The REACH radiometer for detecting the 21-cm hydrogen signal from redshift z ≈ 7.5–28

Nature Astronomy (2022)

Eloy de Lera Acedo Dirk I. L. de Villiers N. Razavi‐Ghods Will Handley Anastasia Fialkov

SIGNAL (programming language)

10.1038/s41550-022-01709-9

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Citations (65)

Digitizing MEXART -- System Overview and Verification

arXiv (Cornell University) (2021)

Alessio Magro J. Borg Riccardo Chiello D. Cutajar Kristian Zarb Adami

The Mexican Array Radio Telescope (MEXART), located in the state of Michoacan in Mexico, has been operating in an analog fashion, utilizing a Butler Matrix to generate fixed beams on the sky, since its inception. Calibrating this instrument has proved difficult, leading to loss in sensitivity. It was also a rigid setup, requiring manual intervention and tuning for different observation requirements. The RF system has now been replaced with a digital one. This digital backend is a hybrid system utilizing both FPGA-based technology and GPU acceleration, and is capable of automatically calibrating the different rows of the array, as well as generating a configurable number of frequency-domain synthesized beams to towards selected locations on the sky. A monitoring and control system, together with a full-featured web-based front-end, has also been developed, greatly simplifying the interaction with the instrument. This paper presents the design, implementation and deployment of the new digital backend, including preliminary analysis of system performance and stability.

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Receiver design for the REACH global 21-cm signal experiment

Experimental Astronomy (2025)

I. L. V. Roque N. Razavi‐Ghods Steven Carey John A. Ely Will Handley

We detail the REACH radiometric system designed to enable measurements of the 21-cm neutral hydrogen line. Included is the radiometer architecture and end-to-end system simulations as well as a discussion of the challenges intrinsic to highly-calibratable system development. Following this, we share laboratory results based on the calculation of noise wave parameters utilising an over-constrained least squares approach. For five hours of integration on a custom-made source with comparable impedance to that of the antenna used in the field, we demonstrate a calibration RMSE of 80 mK. This paper therefore documents the state of the calibrator and data analysis in December 2022 in Cambridge before shipping to South Africa.

SIGNAL (programming language)

10.1007/s10686-024-09975-3

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A Digital Beamformer for the PHAROS2 Phased Array Feed

Journal of Astronomical Instrumentation (2020)

A. Melis Riccardo Chiello G. Comoretto R. Concu Alessio Magro

PHased Arrays for Reflector Observing Systems (PHAROS) is a C-band (4–8[Formula: see text]GHz) Phased Array Feed (PAF) receiver designed to operate from the primary focus of a large single-dish radio astronomy antenna. It consists of an array of 220-element Vivaldi antennas ([Formula: see text] polarization), cryogenically cooled at roughly 20[Formula: see text]K along with low noise amplifiers (LNAs), and of analogue beamformers cryogenically cooled at roughly 80[Formula: see text]K. PHAROS2, the upgrade of PHAROS, is a PAF demonstrator developed in the framework of the Square Kilometer Array Advanced Instrumentation Program (SKA AIP) with the goal of investigating the potential of the PAF technologies at high frequencies in view of their possible application on the SKA dish telescopes. The PHAROS2 design includes new cryogenically cooled LNAs with state-of-the-art performance, a digital beamformer capable of synthesizing four beams from a sub-array of 24 single-polarization antenna elements, and a C-band multi-channel Warm Section receiver capable of analogue filtering and down-converting the signals from the antennas to a suitable frequency range at the input of the digital backend, providing an instantaneous bandwidth of 275[Formula: see text]MHz for each signal. In this paper, we describe the design and performance of the PHAROS2 digital backend/beamformer, based on the Italian Tile Processing Module (ITPM) hardware, which was initially developed for the SKA Low Frequency Aperture Array (LFAA). The backend was adapted to perform the beamforming for our PAF application. We describe the implementation of the beamformer on the Field Programmable Gate Arrays (FPGAs) of the ITPM and how the backend was successfully used to synthesize four independent beams, both in the laboratory (across the entire 275[Formula: see text]MHz instantaneous bandwidth) and during on-field observations at the BEST-2 array (across 16[Formula: see text]MHz instantaneous bandwidth), which is a subset of the Northern Cross Radio Telescope (located in the district of Bologna, Italy). The beamformer design allows re-scaling to a greater number of beams and wider bandwidths.

Reflector (photography)

10.1142/s2251171720500130

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Citations (7)

The low frequency receivers for SKA 1-low: Design and verification

P. Benthem Marchei Gerbers J.G. Bij de Vaate Stefan Wynholds J. E. Bast

The initial phase of the Square Kilometre Array (SKA) [1] is represented by a ~10% instrument and construction should start in 2018. SKA 1-Low, a sparse Aperture Array (AA) covering the frequency range 50 to 350 MHz, will be part of this. This instrument will consist of 512 stations, each hosting 256 antennas creating a total of 131,072 antennas. A first verification system towards SKA 1-Low, Aperture Array Verification System 1 (AAVSl), is being deployed and validated in 2017.

Aperture (computer memory)

Square (algebra)

10.23919/ursigass.2017.8104992

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The Aperture Array Verification System 1: System overview and early commissioning results.

arXiv (Cornell University) (2021)

P. Benthem R. B. Wayth Eloy de Lera Acedo Kristian Zarb Adami M. Alderighi

The design and development process for the Square Kilometre Array (SKA) radio telescope, the Low Frequency Aperture Array component, was progressed during the SKA pre-construction phase by an international consortium, with the goal of meeting requirements for a critical design review. As part of the development process a full-sized prototype SKA Low station was deployed, the Aperture Array Verification System 1 (AAVS1). We provide a system overview and describe the commissioning results of AAVS1, which is a low frequency radio telescope with 256 dual-polarisation log-periodic dipole antennas working as a phased array. A detailed system description is provided, including an in-depth overview of relevant sub-systems, ranging from hardware, firmware, software, calibration,and control sub-systems. Early commissioning results cover initial bootstrapping, array calibration, stability testing, beam-forming,and on-sky sensitivity validation. Lessons learned are presented, along with future developments.

Firmware

Aperture (computer memory)

Installation

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