EVLA Correlator

NRC-HIA is constructing a special-purpose supercomputer called a correlator for the Expanded Very Large Array (EVLA) project. The Very Large Array (VLA) is an array of twenty-seven 25 m antennas in New Mexico, which is currently being upgraded (expanded) in bandwidth, sensitivity, and signal processing capability. This is a joint US-Canada-Mexico project, costing nearly $100 million, and Canada, through NRC-HIA, is contributing a $20 million correlator.

The correlator consists of nearly 300 large printed circuit boards all interconnected by 1000 cables, each carrying nearly 10 Gbits/sec of data. Each circuit board is 16” × 19”, contains 28 layers, tens of thousands of wires as fine as a human hair, and thousands of components, including up to 200 Ball Grid Array devices with up to 1000 solder points each. Each antenna is capable of 16 GHz of bandwidth resulting in 96 Gbits/sec per antenna flowing to the correlator, and the correlator must calculate the cross-correlation function for every pair of antennas (a “baseline”), handling up to 32 antennas (496 baselines). In the correlator, each baseline produces 16,000 to 4 million spectral channels; these channels help astronomers determine the wavelength content of astronomical sources.

The correlator is mostly FPGA (Field Programmable Gate Array) based, but does include a custom ASIC (Application Specific Integrated Circuit) with 16 million transistors fabricated in 130 nm CMOS.

Related Information

Institutes:

• NRC Herzberg Institute of Astrophysics