Characterizing the performance of high-speed data converters for RFSoC-based radio astronomy receivers

Monthly Notices of the Royal Astronomical Society Oxford University Press 501:4 (2020) 5096-5104

Authors:

Chao Liu, Michael Jones, Angela Taylor

Abstract:

RF system-on-chip (RFSoC) devices provide the potential for implementing a complete radio astronomy receiver on a single board, but performance of the integrated analogue-to-digital converters (ADCs) is critical. We have evaluated the performance of the data converters in the Xilinx ZU28DR RFSoC, which are 12-bit, 8-fold interleaved converters with a maximum sample speed of 4.096 Giga-sample per second (GSPS). We measured the spurious-free dynamic range (SFDR), signal-to-noise and distortion (SINAD), effective number of bits (ENOB), intermodulation distortion (IMD), and cross-talk between adjacent channels over the bandwidth of 2.048 GHz. We both captured data for off-line analysis with floating-point arithmetic, and implemented a real-time integer arithmetic spectrometer on the RFSoC. The performance of the ADCs is sufficient for radio astronomy applications and close to the vendor specifications in most of the scenarios. We have carried out spectral integrations of up to 100 s and stability tests over tens of hours and find thermal noise-limited performance over these time-scales.

Resolved observations at 31 GHz of spinning dust emissivity variations in rho Oph

MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY 495:3 (2020) 3482-3493

Authors:

Carla Arce-Tord, Matias Vidal, Simon Casassus, Miguel Carcamo, Clive Dickinson, Brandon S Hensley, Ricardo Genova-Santos, J Richard Bond, Michael E Jones, Anthony CS Readhead, Angela C Taylor, J Anton Zensus

Abstract:

© 2020 The Author(s) Published by Oxford University Press on behalf of the Royal Astronomical Society. The ρ Oph molecular cloud is one of the best examples of spinning dust emission, first detected by the cosmic background imager (CBI). Here, we present 4.5 arcmin observations with CBI 2 that confirm 31 GHz emission from ρ Oph W, the PDR exposed to B-Type star HD 147889, and highlight the absence of signal from S1, the brightest IR nebula in the complex. In order to quantify an association with dust-related emission mechanisms, we calculated correlations at different angular resolutions between the 31 GHz map and proxies for the column density of IR emitters, dust radiance, and optical depth templates. We found that the 31 GHz emission correlates best with the PAH column density tracers, while the correlation with the dust radiance improves when considering emission that is more extended (from the shorter baselines), suggesting that the angular resolution of the observations affects the correlation results. A proxy for the spinning dust emissivity reveals large variations within the complex, with a dynamic range of 25 at 3σ and a variation by a factor of at least 23, at 3σ, between the peak in ρ Oph W and the location of S1, which means that environmental factors are responsible for boosting spinning dust emissivities locally.

The C-Band All-Sky Survey (C-BASS): total intensity point source detection over the northern sky

Monthly Notices of the Royal Astronomical Society Oxford University Press (2020) staa1572

Authors:

Rdp Grumitt, Angela Taylor, Luke Jew, Michael E Jones, C Dickinson, A Barr, R Cepeda-Arroita, Hc Chiang, Se Harper, Hm Heilgendorff, JL Jonas, JP Leahy, Jamie Leech, TJ Pearson, MW Peel, ACS Readhead, J Sievers

Abstract:

We present a point source detection algorithm that employs the second order Spherical Mexican Hat Wavelet filter (SMHW2), and use it on C-BASS northern intensity data to produce a catalogue of point sources. The SMHW2 allows us to filter the entire sky at once, avoiding complications from edge effects arising when filtering small sky patches. The algorithm is validated against a set of Monte Carlo simulations, consisting of diffuse emission, instrumental noise, and various point source populations. The simulated source populations are successfully recovered. The SMHW2 detection algorithm is used to produce a $4.76\,\mathrm{GHz}$ northern sky source catalogue in total intensity, containing 1729 sources and covering declinations $\delta\geq-10^{\circ}$. The C-BASS catalogue is matched with the GB6 and PMN catalogues over their common declinations. From this we estimate the $90\%$ completeness level to be approximately $630\,\mathrm{mJy}$, with a corresponding reliability of $95\%$, when applying a Galactic mask covering $20\%$ of the sky. We find the C-BASS and GB6/PMN flux density scales to be consistent with one another to within $3\%$. The absolute positional offsets of C-BASS sources from matched GB6/PMN sources peak at approximately $3.5\,\mathrm{arcmin}$.

Progress Report on the Large-Scale Polarization Explorer

JOURNAL OF LOW TEMPERATURE PHYSICS Springer Science and Business Media LLC 200:5-6 (2020) 374-383

Authors:

L Lamagna, G Addamo, Par Ade, C Baccigalupi, Am Baldini, Pm Battaglia, E Battistelli, A Bau, M Bersanelli, M Biasotti, C Boragno, A Boscaleri, B Caccianiga, S Caprioli, F Cavaliere, F Cei, Ka Cleary, F Columbro, G Coppi, A Coppolecchia, D Corsini, F Cuttaia, G D'Alessandro, P de Bernardis, G De Gasperis

Abstract:

© 2020, Springer Science+Business Media, LLC, part of Springer Nature. The large-scale polarization explorer (LSPE) is a cosmology program for the measurement of large-scale curl-like features (B-modes) in the polarization of the cosmic microwave background. Its goal is to constrain the background of inflationary gravity waves traveling through the universe at the time of matter-radiation decoupling. The two instruments of LSPE are meant to synergically operate by covering a large portion of the northern microwave sky. LSPE/STRIP is a coherent array of receivers planned to be operated from the Teide Observatory in Tenerife, for the control and characterization of the low-frequency polarized signals of galactic origin; LSPE/SWIPE is a balloon-borne bolometric polarimeter based on 330 large throughput multi-moded detectors, designed to measure the CMB polarization at 150 GHz and to monitor the polarized emission by galactic dust above 200 GHz. The combined performance and the expected level of systematics mitigation will allow LSPE to constrain primordial B-modes down to a tensor/scalar ratio of 10 - 2. We here report the status of the STRIP pre-commissioning phase and the progress in the characterization of the key subsystems of the SWIPE payload (namely the cryogenic polarization modulation unit and the multi-moded TES pixels) prior to receiver integration.

Permittivity and permeability of epoxy-magnetite powder composites at microwave frequencies

Journal of Applied Physics 127:4 (2020)

Authors:

M Zannoni, T Ghigna, Me Jones, A Simonetto

Abstract:

© 2020 Author(s). Radio, millimeter, and sub-millimeter astronomy experiments as well as remote sensing applications often require castable absorbers with well known electromagnetic properties to design and realize calibration targets. In this context, we fabricated and characterized two samples using different ratios of two easily commercially available materials: epoxy (Stycast 2850FT) and magnetite (F e 3 O 4) powder. We performed transmission and reflection measurements from 7 GHz up to 170 GHz with a vector network analyzer equipped with a series of standard horn antennas. Using an empirical model, we analyzed the data to extract complex permittivity and permeability from transmission data; then, we used reflection data to validate the results. In this paper, we present the sample fabrication procedure, analysis method, parameter extraction pipeline, and results for two samples with different epoxy-powder mass ratios.