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The CARMA correlator

Hawkins, D. W. and Woody, D. P. and Wiitala, B. and Fredsti, J. and Rauch, K. P. (2004) The CARMA correlator. In: Millimeter and Submillimeter Detectors for Astronomy II. Proceedings of SPIE. No.5498. Society of Photo-optical Instrumentation Engineers (SPIE) , Bellingham, WA, pp. 567-578. ISBN 9780819454300.

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The Combined Array for Research in Millimeter-wave Astronomy (CARMA) requires a flexible correlator to process the data from up to 23 telescopes and up to 8GHz of receiver bandwidth. The Caltech Owens Valley Broadband Reconfigurable Array (COBRA) correlator, developed for use at the Owens Valley millimeter-wave array and being used by the Sunyaev-Zeldovich Array (SZA), will be adapted for use by CARMA. The COBRA correlator system, a hybrid analog-digital design, consisting of downconverters, digitizers and correlators will be presented in this paper. The downconverters receive an input IF of 1-9GHz and produce a selectable output bandwidth of 62.5MHz, 125MHz, 250MHz, or 500MHz. The downconverter output is digitized at 1Gsample/s to 2-bits per sample. The digitized data is optionally digitally filtered to produce bands narrower than 62.5MHz (down to 2MHz). The digital correlator system is a lag- or XF-based system implemented using Field-Programmable Gate Arrays (FPGAs). The digital system implements delay lines, calculates the autocorrelations for each antenna, and the cross-correlations for each baseline. The number of lags, and hence spectral channels, produced by the system is a function of the input bandwidth; with the 500MHz band having the coarsest resolution, and the narrowest bandwidths having the finest resolution.

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Additional Information:© 2004 Society of Photo-optical Instrumentation Engineers (SPIE). This paper has been produced on behalf of the CARMA consortium, and represents the work of scientists, engineers and technicians at the University of California (Berkeley), the University of Maryland (College Park), the University of Illinois (Urbana-Champaign), the California Institute of Technology Owens Valley Radio Observatory and the University of Chicago. The OVRO and BIMA arrays and CARMA are partially supported by National Science Foundation grants NSF-9981546, NSF-AST9983108, NSF- AST9981363, NSF-AST991289 and NSF 011616558. The SZA is supported by NSF grants AST-0096913 and PHY-0114422, the James S. McDonnell Foundation, the David and Lucile Packard Foundation and the University of Chicago.
Funding AgencyGrant Number
James S. McDonnell FoundationUNSPECIFIED
David and Lucile Packard FoundationUNSPECIFIED
University of ChicagoUNSPECIFIED
Subject Keywords:Radio astronomy, interferometry, lag (XF) correlator
Series Name:Proceedings of SPIE
Issue or Number:5498
Record Number:CaltechAUTHORS:20190117-145734624
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Official Citation:David W. Hawkins, David P. Woody, B. Wiitala, J. Fredsti, K. P. Rauch, "The CARMA correlator," Proc. SPIE 5498, Millimeter and Submillimeter Detectors for Astronomy II, (8 October 2004); doi: 10.1117/12.552430
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:92350
Deposited By: Tony Diaz
Deposited On:18 Jan 2019 02:44
Last Modified:16 Nov 2021 03:49

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