Square Kilometre Array Low Atomic commercial off-the-shelf correlator and beamformer

The Square Kilometre Array Low is a next generation radio telescope, consisting of 512 antenna stations spread over 65 km, to be built in Western Australia. The correlator and beamformer (CBF) design is central to the telescope signal processing. CBF receives 6 Tera-bits-per-second (Tbps) of station data continuously and processes it in real time with a compute load of 2 Peta-operations-per-second (Pops). The correlator calculates up to 22 million cross products between all pairs of stations, whereas the beamformers (BFs) coherently sum station data to form more than 500 beams. The output of the correlator is up to 7 Tbps, and the BF 2 Tbps. The design philosophy, called "Atomic COTS," is based on commercial off-the-shelf (COTS) hardware. Data routing is implemented in network switches programmed using the Programming Protocol-Independent Packet Processors (P4) language and the signal processing occurs in COTS field-programmable gate array (FPGA) cards. The P4 language allows routing to be determined from the metadata in the Ethernet packets from the stations. That is, metadata describing the contents of the packet determines the routing. Each FPGA card inputs a fraction of the overall bandwidth for all stations and then implements the processing needed to generate complete science data products. Generation of complete science products in a single FPGA is named here as Atomic processing. A Tango distributed control system configures the multitude of processing modes as well as maintaining the overall health of the CBF system hardware. The resulting 6 Tbps in and 9 Tbps out, 2 Pops Atomic COTS network attached accelerator occupies five racks and consumes 60 kW. (C) The Authors. Published by SPIE under a Creative Commons Attribution 4.0 International License.