1. Highly Scalable Packetised correlators Jason Manley CASPER workshop 2009

2. Contents • Where we’ve come from • CASPER • Correlator design • Dataflow • Engine operations • Scalability • Present and future deployments

3. In the beginning… Big dish Control & Monitoring Analogue processor Computing backend

4. Interferometry… Green Bank 300ft ATA

5. …more recently… EVLA baseline board (Carlson, 2006)

6. CASPERCenter for Astronomy Signal Processing and Electronics Research • Open-source, collaborative environment • Reusable, platform-independent gateware • Modular, upgradeable hardware • Low instrument NRE, shared by the community • Enables rapid development (8 instruments / 2 years) • Industry standard communication protocols • Low Cost

7. CASPER DBE concept

8. CASPER DBE concept

9. Clocking • Clocks: • Locally synchronous, globally asynchronous. • Sampling clock synchronized at F engines. • X engines each run off independent local clock. • Synchronized using global 1pps signal at ADCs • Propagated to X engines using out-of-band signaling on XAUI links. • Headers labeling and timestamping10GbE Ethernet packet data.

10. Correlator Overview

11. How does it scale?

12. Processing power doubling every two years • V4 = ½ power requirements of V2Pro* * Manufacturers claim - Xilinx Inc.

13. Existing systems: PAPER - Green Bank • 8 dual-pol antennas, 150MHz. • 1st Generation: one BEE2 & four IBOBs. • First deployment of packetized system. • Continuous upgrades.

14. Existing systems: Northern Cross, Medicina, Italy • Designed and deployed in under 2 weeks. • 32 single-pol antennas, 32 MHz. • 1st Generation: • one BEE2 • eight IBOBs.

15. New deployments: KAT-7 • 7 dual-pol antennas, 400MHz. • Pure ROACH. • New control and monitoring interface (KATCP), coarse delay, high speed output (less than 100ms). • Expected early 2010.

16. New deployments: GMRT • 32 dual-pol inputs, 400MHz bandwidth. • Collaboration – shares design with KAT-7.

17. New deployments: PSA-32/64/128/256 • PAPER in South Africa, staged deployment • Up to 256 antennas, 100MHz • Generation 1.5 (IBOB+ROACH) initially, • Generation 2.5 (ROACH + ROACH-II) eventually. • First field deployment of ROACH system. • Correlator deployment starting in January!

18. Jason Manley jason_manley@hotmail.com