Digital Signal Processing Using Stream High Performance Computing: A 512-Input Broadband Correlator for Radio Astronomy

Abstract

A "large-N" correlator that makes use of Field Programmable Gate Arrays and Graphics Processing Units has been deployed as the digital signal processing system for the Long Wavelength Array station at Owens Valley Radio Observatory (LWA-OV), to enable the Large Aperture Experiment to Detect the Dark Ages (LEDA). The system samples a ̃ 100 MHz baseband and processes signals from 512 antennas (256 dual polarization) over a ̃ 58 MHz instantaneous sub-band, achieving 16.8 Tops s<SUP>-1</SUP> and 0.236 Tbit s<SUP>-1</SUP> throughput in a 9 kW envelope and single rack footprint. The output data rate is 260 MB s<SUP>-1</SUP> for 9-s time averaging of cross-power and 1 s averaging of total power data. At deployment, the LWA-OV correlator was the largest in production in terms of N and is the third largest in terms of complex multiply accumulations, after the Very Large Array and Atacama Large Millimeter Array. The correlator's comparatively fast development time and low cost establish a practical foundation for the scalability of a modular, heterogeneous, computing architecture.