Scalable Digital Receiver for Multi-Element Radio Telescopes

Abstract

Modern and upcoming radio telescopes at low frequencies are often characterized by hundreds or thousands of antenna elements operating at wide bandwidths up to about 0.5GHz. A spectral correlator for such an array is required to estimate the cross-power spectrum of the response of each element with that of every other element with a high spectral resolution. The resulting all-to-all connectivity between signals from the entire array poses a serious bottleneck. In this paper, we propose a simple digital receiver architecture that interfaces the digitized time series from a large number of antenna elements to a High-Performance Computing (HPC) cluster through a communication switch to overcome the data ingest bottleneck. Each HPC node can then perform wideband processing in steps of finite but significant time-slices for the entire array. We explain in detail the implementation of our architecture for the proposed expansion of the Ooty Wide Field Array (OWFA) into a 1056 element array. Since the proposed digital receiver is based on Field Programmable Gate Array (FPGA), it can be reconfigured for different applications. This is illustrated by considering the case of Phased Array Feeds (PAF) for the proposed expanded Giant Metrewave Radio Telescope (eGMRT).