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A high performance cost-effective digital complex correlator for an X-band polarimetry survey.

Bergano M, Rocha A, Cupido L, Barbosa D, Villela T, Boas JV, Rocha G, Smoot GF - Springerplus (2016)

Bottom Line: The hardware constraints cover the implemented VLSI hardware description language code and the preliminary results.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.

View Article: PubMed Central - PubMed

Affiliation: Department of Electronics, Telecommunication and Informatics (DETI), Instituto de Telecomunicações, University of Aveiro, Campus Universitário de Santiago, 3810-193 Aveiro, Portugal.

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.

No MeSH data available.


Linear left polarization Stokes I parameter: simulated versus measured
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Fig8: Linear left polarization Stokes I parameter: simulated versus measured

Mentions: The best approach here was to send the Stokes parameters time series, for later analysis, to a small computer using a GPIO interface. Three scenarios were considered: one for linear polarization, one for circular polarization and other for partial polarization. Two sinusoids with different amplitudes and frequencies for each polarization are created to mimic these polarizations Fig. 6. We opted to present the results of a circular polarization situation, that is, two sinusoids with the same amplitude and frequency and phase imbalance of π/2 radians. The power of the testing signal was manually switched during a few seconds through the levels of -12 dBm, -18 dBm, -24 dBm and -30 dBm. The test results are shown in Figs. 7 and in 8.Fig. 6


A high performance cost-effective digital complex correlator for an X-band polarimetry survey.

Bergano M, Rocha A, Cupido L, Barbosa D, Villela T, Boas JV, Rocha G, Smoot GF - Springerplus (2016)

Linear left polarization Stokes I parameter: simulated versus measured
© Copyright Policy - OpenAccess
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4837755&req=5

Fig8: Linear left polarization Stokes I parameter: simulated versus measured
Mentions: The best approach here was to send the Stokes parameters time series, for later analysis, to a small computer using a GPIO interface. Three scenarios were considered: one for linear polarization, one for circular polarization and other for partial polarization. Two sinusoids with different amplitudes and frequencies for each polarization are created to mimic these polarizations Fig. 6. We opted to present the results of a circular polarization situation, that is, two sinusoids with the same amplitude and frequency and phase imbalance of π/2 radians. The power of the testing signal was manually switched during a few seconds through the levels of -12 dBm, -18 dBm, -24 dBm and -30 dBm. The test results are shown in Figs. 7 and in 8.Fig. 6

Bottom Line: The hardware constraints cover the implemented VLSI hardware description language code and the preliminary results.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.

View Article: PubMed Central - PubMed

Affiliation: Department of Electronics, Telecommunication and Informatics (DETI), Instituto de Telecomunicações, University of Aveiro, Campus Universitário de Santiago, 3810-193 Aveiro, Portugal.

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.

No MeSH data available.