A full-band voltage beam forming mode for the MurchisonWidefield Array digital receiver

T. Prabu9*, K. S. Srivani9, P. A. Kamini9, S. Madhavi9, A. A. Deshpande9, N. Udaya Shankar9, R. Subrahmanyan9,17, F. Briggs2,17, A. Roshi8, S. M. Ord4,17, N. D. R. Bhat4, S. Tremblay4,17, S. J. I. Oronsaye4, E. Morgan7, R. Goeke7, M. Waterson4,2, D. Emrich4, B. Crosse4, A. Williams4, D. Pallot4, M. R. Gopalakrishna9, J. Pathikulangara18, J. D. Bunton18, G. Hampson3, G. Bernardi5,10,19, J. D. Bowman1, R. J. Cappallo6, B. E. Corey6, L. J. Greenhill5, B. J. Hazelton14, J. N. Hewitt7, M. Johnston-Hollitt16, D. L. Kaplan15, J. C. Kasper5, E. Kratzenberg6, C. J. Lonsdale6, M. J. Lynch4, S. R. McWhirter6, D. A. Mitchell3,17, M. F. Morales14, D. Oberoi11, A. E. E. Rogers6, S. J. Tingay4,17, R. B. Wayth4,17, R. L. Webster12,17, A. R. Whitney6 and C. L. Williams7
1Arizona State University, Tempe, USA
2The Australian National University, Canberra, Australia
3CSIRO Astronomy and Space Science, Marsfield, Australia
4Curtin University, Perth, Australia
5Harvard-Smithsonian Center for Astrophysics, Cambridge, USA
6MIT Haystack Observatory, Westford, MA, USA
7MIT Kavli Institute for Astrophysics and Space Research, Cambridge, USA
8National Radio Astronomy Observatory, Charlottesville, USA
9Raman Research Institute, Bangalore, India
10Square Kilometre Array South Africa (SKA SA), Cape Town, South Africa
11National Center for Radio Astrophysics, Pune, India
12The University of Melbourne, Melbourne, Australia
13University of Sydney, Sydney, Australia
14University of Washington, Seattle, USA
15University of Wisconsin–Milwaukee, Milwaukee, USA
16Victoria University of Wellington, New Zealand
17ARC Centre of Excellence for All-sky Astrophysics (CAASTRO)
18CSIRO Computational Informatics, Marsfield, Australia
19Department of Physics and Electronics, Rhodes University, Grahamstown, South Africa

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Abstract

A digital receiver at the Murchison Widefield Array (MWA) processes signal from eight MWA tiles for a band between 80 and 300 MHz. The digitized outputs are processed in the digital receiver using a polyphase filter bank to get a 1.28 MHz wide sub-bands. During a normal operation, 24 such sub-bands (corresponding to a 30.72 MHz band) are selected and sent out for processing in an FX correlator. To facilitate sensitive targeted searches and fast transient observations with the MWA, the digital receiver is enhanced to form a new mode, where a voltage beam is formed across the 80 to 300 MHz band. The digital receiver’s data path and the firmware logic are enhanced to achieve this mode. The enhanced digital receiver can phase the full-band signals from eight tiles to form the voltage beams at each station. Now, the development of this beamformer mode to the MWA digital receiver is complete, and the new functionality is being tested in the lab. We present here briefly an introduction, the implementation of the new mode, the current status and the future plans.



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Keywords :Murchison Widefield Array – digital receiver – voltage beam – phased array – fast transient