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Please use this identifier to cite or link to this item: http://hdl.handle.net/2289/5857
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dc.contributor.authorPatra, Nipanjana-
dc.contributor.authorSubrahmanyan, Ravi-
dc.contributor.authorRaghunathan, A.-
dc.contributor.authorUdaya Shankar, N.-
dc.date.accessioned2014-02-20T07:29:02Z-
dc.date.available2014-02-20T07:29:02Z-
dc.date.issued2013-08-
dc.identifier.citationExperimental Astronomy, 2013, Vol. 36, p319-370.en
dc.identifier.issn1572-9508-
dc.identifier.issn0922-6435 (Online)-
dc.identifier.urihttp://hdl.handle.net/2289/5857-
dc.descriptionRestricted Access. An open-access version is available at arXiv.org (one of the alternative locations)en
dc.description.abstractSARAS is a correlation spectrometer purpose designed for precision measurements of the cosmic radio background and faint features in the sky spectrum at long wavelengths that arise from redshifted 21-cm from gas in the reionization epoch. SARAS operates in the octave band 87.5–175 MHz. We present herein the system design arguing for a complex correlation spectrometer concept. The SARAS design concept provides a differential measurement between the antenna temperature and that of an internal reference termination, with measurements in switched system states allowing for cancellation of additive contaminants from a large part of the signal flow path including the digital spectrometer. A switched noise injection scheme provides absolute spectral calibration. Additionally, we argue for an electrically small frequency-independent antenna over an absorber ground. Various critical design features that aid in avoidance of systematics and in providing calibration products for the parametrization of other unavoidable systematics are described and the rationale discussed. The signal flow and processing is analyzed and the response to noise temperatures of the antenna, reference termination and amplifiers is computed. Multi-path propagation arising from internal reflections are considered in the analysis, which includes a harmonic series of internal reflections. We opine that the SARAS design concept is advantageous for precision measurement of the absolute cosmic radio background spectrum; therefore, the design features and analysis methods presented here are expected to serve as a basis for implementations tailored to measurements of a multiplicity of features in the background sky at long wavelengths, which may arise from events in the dark ages and subsequent reionization era.en
dc.language.isoenen
dc.publisherSpringeren
dc.relation.urihttp://adsabs.harvard.edu/abs/2013ExA....36..319Pen
dc.relation.urihttp://arxiv.org/abs/1211.3800en
dc.relation.urihttp://dx.doi.org/10.1007/s10686-013-9336-3en
dc.rights2013 Springeren
dc.titleSARAS: a precision system for measurement of the cosmic radio background and signatures from the epoch of reionizationen
dc.typeArticleen
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