  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 ~100MHz baseband and processes signals from 512
antennas (256 dual polarization) over a ~58MHz instantaneous sub-band,
achieving 16.8Tops/s and 0.236 Tbit/s throughput in a 9kW envelope and single
rack footprint. The output data rate is 260MB/s for 9 second time averaging of
cross-power and 1 second 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.
