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

Naldi, G.; Mattana, A.; Pastore, S.; Alderighi, M.; Adami, Kristian Zarb; Schillirò, F.; Aminaei, A.; Baker, J. O.; Belli, Carolina; Comoretto, G.; Chiarucci, Simone; Chiello, Riccardo; D'Angelo, S.; Mura, Gabriele Dalle; Marco, Andrea De; Halsall, R.; Magro, Alessio; Monari, Jader; Roberts, M. J.; Perini, Federico; Poloni, M.; Pupillo, G.; Rusticelli, Simone; Schiaffino, Marco; Zaccaro, Emanuele

doi:10.1142/s2251171716410142

Cited by 28 publications

(15 citation statements)

References 4 publications

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“…Observations were conducted using the Engineering Development Array, version 2 (EDA2: Figure 1), an array of 256 MWA antennas arranged in an SKA_low station configuration (station diameter of 35 m) and located at the MRO (Wayth et al in preparation). Analogue signal chains from the individual antennas (both polarisations; X and Y) are digitised and coarse-channelised in the firmware (Comoretto et al 2017) implemented in Tile Processing Modules (TPM; Naldi et al 2017). The coarse-channelised voltage streams are received on the data acquisition computer and signals from individual antennas are correlated using the xGPU (Clark, La Plante, & Greenhill 2011) software correlator.…”

Section: Observationsmentioning

confidence: 99%

A survey of spatially and temporally resolved radio frequency interference in the FM band at the Murchison Radio-astronomy Observatory

Tingay

Sokołowski

Wayth

et al. 2020

Publ. Astron. Soc. Aust.

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We present the first survey of radio frequency interference (RFI) at the future site of the low frequency Square Kilometre Array (SKA), the Murchison Radio-astronomy Observatory (MRO), that both temporally and spatially resolves the RFI. The survey is conducted in a 1 MHz frequency range within the FM band, designed to encompass the closest and strongest FM transmitters to the MRO (located in Geraldton, approximately 300 km distant). Conducted over approximately three days using the second iteration of the Engineering Development Array in an all-sky imaging mode, we find a range of RFI signals. We are able to categorise the signals into: those received directly from the transmitters, from their horizon locations; reflections from aircraft (occupying approximately 13% of the observation duration); reflections from objects in Earth orbit; and reflections from meteor ionisation trails. In total, we analyse 33 994 images at 7.92 s time resolution in both polarisations with angular resolution of approximately 3.5 $^{\circ}$ , detecting approximately forty thousand RFI events. This detailed breakdown of RFI in the MRO environment will enable future detailed analyses of the likely impacts of RFI on key science at low radio frequencies with the SKA.

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Section: Observationsmentioning

confidence: 99%

A survey of spatially and temporally resolved radio frequency interference in the FM band at the Murchison Radio-astronomy Observatory

Tingay

Sokołowski

Wayth

et al. 2020

Publ. Astron. Soc. Aust.

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“…11(b) where the full receiving system of SKA1-Low has been exploited, i.e. optical fiber link, receiver (including digital step attenuator) and digital acquisition system [25]. The higher complexity of the receiver justifies the 6-dB difference in the predicted absolute values, i.e.…”

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confidence: 99%

Test-Driven Design of an Active Dual-Polarized Log-Periodic Antenna for the Square Kilometre Array

Bolli

Mezzadrelli

Monari

et al. 2020

IEEE Open J. Antennas Propag.

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An active dual-polarized Log-Periodic antenna has been designed to meet the requirements of the low-frequency (50-350 MHz) radio telescope of the Square Kilometre Array (SKA). The integration of antenna and low noise amplifier has been conceived in order to achieve a high degree of testability. This aspect has been found to be crucial to obtain a smooth frequency response compatible with the SKA science cases. The design has also been driven by other factors such as the large-volume production (more than 130 000 antennas will be built) and the environmental conditions of the harsh Australian desert. A specific verification approach based on both wideband radiometric spectral and spatial measurements in relevant laboratory and in-situ conditions has been developed. Electromagnetic analyses and experimental results exhibit a very good agreement. In December 2019, this antenna was part of the reference solution for the System Critical Design Review of the SKA.

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“…The analogue signals from individual antennas (X and Y polarisations) are converted to optical signals near the antennas and transported over the 5.5 km fibre to the central processing facility. The EDA2 and AAVS2 both use tile processing modules (TPM; Naldi et al 2017) to digitise incoming signals. The TPM is a 32input signal processing board designed for SKA-Low.…”

Section: Ska-low Prototype Stationsmentioning

confidence: 99%

A Southern-Hemisphere all-sky radio transient monitor for SKA-Low prototype stations

Sokołowski

Wayth

Price

et al. 2021

Publ. Astron. Soc. Aust.

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We present the first Southern-Hemisphere all-sky imager and radio-transient monitoring system implemented on two prototype stations of the low-frequency component of the Square Kilometre Array (SKA-Low). Since its deployment, the system has been used for real-time monitoring of the recorded commissioning data. Additionally, a transient searching algorithm has been executed on the resulting all-sky images. It uses a difference imaging technique to enable identification of a wide variety of transient classes, ranging from human-made radio-frequency interference to genuine astrophysical events. Observations at the frequency 159.375 MHz and higher in a single coarse channel ( $\approx$ 0.926 MHz) were made with 2 s time resolution, and multiple nights were analysed generating thousands of images. Despite having modest sensitivity ( $\sim$ few Jy beam–1), using a single coarse channel and 2-s imaging, the system was able to detect multiple bright transients from PSR B0950+08, proving that it can be used to detect bright transients of an astrophysical origin. The unusual, extreme activity of the pulsar PSR B0950+08 (maximum flux density $\sim$ 155 Jy beam–1) was initially detected in a ‘blind’ search in the 2020 April 10/11 data and later assigned to this specific pulsar. The limitations of our data, however, prevent us from making firm conclusions of the effect being due to a combination of refractive and diffractive scintillation or intrinsic emission mechanisms. The system can routinely collect data over many days without interruptions; the large amount of recorded data at 159.375 and 229.6875 MHz allowed us to determine a preliminary transient surface density upper limit of $1.32 \times 10^{-9} \text{deg}^{-2}$ for a timescale and limiting flux density of 2 s and 42 Jy, respectively. In the future, we plan to extend the observing bandwidth to tens of MHz and improve time resolution to tens of milliseconds in order to increase the sensitivity and enable detections of fast radio bursts below 300 MHz.

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

Cited by 28 publications

References 4 publications

A survey of spatially and temporally resolved radio frequency interference in the FM band at the Murchison Radio-astronomy Observatory

A survey of spatially and temporally resolved radio frequency interference in the FM band at the Murchison Radio-astronomy Observatory

Test-Driven Design of an Active Dual-Polarized Log-Periodic Antenna for the Square Kilometre Array

A Southern-Hemisphere all-sky radio transient monitor for SKA-Low prototype stations

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