Abstract Details
| Name: Girish B. S. Affiliation: Raman Research Institute Conference ID: ASI2015_592 Title : A New Generation Digital Receiver for the Murchison Wide-field Array Authors and Co-Authors : Srivani K. S., Udaya Shankar N., Avinash A. Deshpande, Dwarakanath K. S., Shiv K. Sethi Affiliation: Raman Research Institute, C. V. Raman Avenue, Sadashivanagar, Bengaluru-560080 Abstract Type : Poster Abstract Category : Instrumentation and Techniques Abstract : The Murchison Wide field Array (MWA) is a low frequency interferometric radio telescope located in the Murchison region of Western Australia. The three key science projects of MWA are: 1) search for redshifted HI signals from the Epoch of Reionization (EoR); 2) wide-field searches for transient and variable objects; and 3) wide-field Galactic and extra-galactic surveys. The MWA is the only low frequency (80 - 300 MHz) Precursor for the Square Kilometre Array (SKA) and is the first of the three SKA Precursors to be fully operational for science (since July 2013). Currently, the MWA consortium is discussing the possibilities of upgrading the array to enhance its scientific productivity. In this presentation, we shall describe a proposal by the Raman Research Institute (RRI) for a new generation Digital Receiver System for phase 2 of MWA that exploits the rapid advances in the processing capabilities of modern FPGAs. The proposed receiver shall be capable of digitizing an analogue signal of bandwidth up to 500 MHz using a 10-bit analogue-to-digital converter (ADC). When compared with the existing receiver which is based on an 8-bit ADC, the proposed receiver provides increased headroom for better RFI management. While the data bandwidth of the existing receiver allows ~10% of the sampled bandwidth to be transported for further processing, the data throughput rate of the proposed receiver will be sufficient to carry the entire observable bandwidth of MWA to the central processing station. This would enhance the sensitivity of the array, when equipped with a wideband correlator. An efficient implementation of a polyphase filter bank-based channelization algorithm is envisaged to channelize the sampled signal into narrow sub bands. Providing access to the entire sampled bandwidth-without flagging off contaminated spectral channels due to aliasing from adjacent sub bands-ensures that there is no undesirable leakage of foreground into the EoR window. Next, this presentation will describe a 2 GHz wide-band precision spectrometer (pSPEC) built and demonstrated at RRI, using two quad 10-bit ADCs followed by an efficient implementation of 8k point channelization architecture inside a Virtex-6 FPGA. With minimal changes, two such pSPEC units could be deployed to serve as a compact digital receiver system for use with 8 tiles of MWA, as has already been in pipeline for use in the Sky Watch Array Network (SWAN) project. This configuration will have about three times the resources available in the present MWA receiver. With this leverage, we are exploring possible co-existence of normal and phased-array modes of MWA. The presentation will conclude with a cost analysis of digital receiver system for phase 2 of MWA. |