title: A high performance cost-effective digital complex correlator for an X-band polarimetry survey.
abstract: The detailed knowledge of the Milky Way radio emission is important to characterize galactic foregrounds masking extragalactic and cosmological signals. The update of the global sky models describing radio emissions over a very large spectral band requires high sensitivity experiments capable of observing large sky areas with long integration times. Here, we present the design of a new 10 GHz (X-band) polarimeter digital back-end to map the polarization components of the galactic synchrotron radiation field of the Northern Hemisphere sky. The design follows the digital processing trends in radio astronomy and implements a large bandwidth (1 GHz) digital complex cross-correlator to extract the Stokes parameters of the incoming synchrotron radiation field. The hardware constraints cover the implemented VLSI hardware description language code and the preliminary results. The implementation is based on the simultaneous digitized acquisition of the Cartesian components of the two linear receiver polarization channels. The design strategy involves a double data rate acquisition of the ADC interleaved parallel bus, and field programmable gate array device programming at the register transfer mode. The digital core of the back-end is capable of processing 32 Gbps and is built around an Altera field programmable gate array clocked at 250 MHz, 1 GSps analog to digital converters and a clock generator. The control of the field programmable gate array internal signal delays and a convenient use of its phase locked loops provide the timing requirements to achieve the target bandwidths and sensitivity. This solution is convenient for radio astronomy experiments requiring large bandwidth, high functionality, high volume availability and low cost. Of particular interest, this correlator was developed for the Galactic Emission Mapping project and is suitable for large sky area polarization continuum surveys. The solutions may also be adapted to be used at signal processing subsystem levels for large projects like the square kilometer array testbeds.
authors.affiliation: Department of Electronics, Telecommunication and Informatics (DETI), Instituto de Telecomunicações, University of Aveiro, Campus Universitário de Santiago, 3810-193 Aveiro, Portugal.
authors.forename: Miguel
authors.initials: M
authors.lastname: Bergano
authors.affiliation: Department of Electronics, Telecommunication and Informatics (DETI), University of Aveiro, Campus Universitário de Santiago, 3810-106 Aveiro, Portugal.
authors.forename: Armando
authors.initials: A
authors.lastname: Rocha
authors.affiliation: LC-Technologies, Aveiro, Portugal.
authors.forename: Luís
authors.initials: L
authors.lastname: Cupido
authors.affiliation: Instituto de Telecomunicações, Campus Universitário de Santiago, 3810-193 Aveiro, Portugal.
authors.forename: Domingos
authors.initials: D
authors.lastname: Barbosa
authors.affiliation: Instituto Nacionals de Pesquisas Espaciais (INPE) - Divisão de Astrofísica - DAS, Av. dos Astronautas, 1.758, Jd. Granja, CEP 12227-010 São Jose dos Campos, SP Brazil.
authors.forename: Thyrso
authors.initials: T
authors.lastname: Villela
authors.affiliation: Instituto Nacionals de Pesquisas Espaciais (INPE) - Divisão de Astrofísica - DAS, Av. dos Astronautas, 1.758, Jd. Granja, CEP 12227-010 São Jose dos Campos, SP Brazil.
authors.forename: José Vilas
authors.initials: JV
authors.lastname: Boas
authors.affiliation: Jet Propulsion Laboratory, M/S 169-327, 4800 Oak Grove Drive, Pasadena, CA 91109 USA ; Caltech, Cahill Building MS 59-33 1200 E. California, Pasadena, CA 91125-3300 USA.
authors.forename: Graça
authors.initials: G
authors.lastname: Rocha
authors.affiliation: Lawrence Berkeley National Lab, 1 Cyclotron Road, MS 50-5005, Berkeley, CA 94720 USA ; Université Paris-Diderot APC, Bâtiment Condorcet, 10 rue Alice Domon et Léonie Duquet, 75205 Paris Cedex 13, France.
authors.forename: George F
authors.initials: GF
authors.lastname: Smoot
keywords: Logic design (hardware); Radioastronomy (astronomy, astrophysics and cosmology); Register-transfer-level implementation (hardware)