1. Georgina Harris1 2-PAD 4 th SKADS Workshop, Lisbon, 2-3 October 2008 2-Polarisations All Digital Dr Georgina Harris / Prof Tony Brown SKADS System Design and Team Leader, University of Manchester Thanks to the 2-PAD Team: Manchester Chris Shenton, Tim Ikin, Aziz AhmedSaid, Richard Whitaker, Tony Brown, Dan Kettle, Mina Panahi Oxford Mike Jones, Kris Zarb Adami, Sasha Shidewy Cambridge Andrew Faulkner Astron Jan Geralt bij de Vaate, Raymond van den Brink 2-P A D 2-Polarisations All Digital2-PAD

2. Georgina Harris2 2-PAD 4 th SKADS Workshop, Lisbon, 2-3 October 2008 2-PAD Aims To produce a flexible platform upon which to test a variety of subsystems for the Aperture Array for the SKA Digital beamforming –Prove it can be done –Realistic technology projections for cost/ power –Low self induced RFI –Low cost interconnects are feasible Dual polarisation measurements Proof of calibration at tile level

3. Georgina Harris3 2-PAD 4 th SKADS Workshop, Lisbon, 2-3 October 2008 2-PAD System Design +ve Reg Ant. polarisation LNA Analog Conditioning PCB Analog Interconnect CAT7? Bunker RFI Shield PSU Analogue Conditioning....... Total 128 inputs 64 elements x2 polarisations Beam combiner Processor....... Output Beams 4 off Beamformer. Processors Processor Control Processor Line Tx/Rx Control Time standard Buffers From other beamformer proc. Beamformer Processing Digital Pre- processor ADC PSU Digital Pre- processor ADC..... Signal Conditioning Rack Processing Rack BunkerOutdoors 64 dual channels Up to ~20m

4. Georgina Harris4 2-PAD 4 th SKADS Workshop, Lisbon, 2-3 October 2008 Antennas 2-PAD will use 3 sets of array antennas Each antenna tile will be 16 x 16 dual polarisation elements The central 8 x 8 elements will be ‘active’, i.e. the signals from these antennas will be amplified and processed The remaining antennas will be ‘loaded’ elements, i.e. they are present only to reduce the edge effects on the central 8 x 8 Each antenna type is due to be produced as a passive tile for RF testing After testing, the active antennas will be used for 2-PAD.

5. Georgina Harris5 2-PAD 4 th SKADS Workshop, Lisbon, 2-3 October 2008 Antennas FlowPAD antenna from our colleagues at Astron used as a reference design by which to benchmark our other antennas

6. Georgina Harris6 2-PAD 4 th SKADS Workshop, Lisbon, 2-3 October 2008 Antennas BECA (Bunny Ear Combline Antenna) Designed by the University of Manchester A development of a Vivaldi Structure

7. Georgina Harris7 2-PAD 4 th SKADS Workshop, Lisbon, 2-3 October 2008 Antennas ORA (Octagon Ring Antenna) Designed by the University of Manchester New Antenna Design – see talk by David Zhang

8. Georgina Harris8 2-PAD 4 th SKADS Workshop, Lisbon, 2-3 October 2008 2-PAD LNA The LNA for each antenna must be impedance matched and designed to integrate mechanically with the antenna There are currently three teams working on LNAs in SKADS for 2-PAD –A completely new single-ended LNA developed in Indium Phosphide in Manchester –A differential LNA designed at ASTRON at 150  impedance for use with FlowPAD and BECA antennas –A differential LNA made up from discrete components in Manchester at 150  for use with FlowPAD and BECA antennas It is likely that the discrete component LNA will be installed on 2-PAD initially, however, it will be possible for each LNA to undergo validation on the 2-PAD platform.

9. Georgina Harris9 2-PAD 4 th SKADS Workshop, Lisbon, 2-3 October 2008 Gain = 72dB Designed constructed and characterised by Richard Morrow Gain Chain Version 1

10. Georgina Harris10 2-PAD 4 th SKADS Workshop, Lisbon, 2-3 October 2008 2-PAD System Design +ve Reg Ant. polarisation LNA Analog Conditioning PCB Analog Twisted Pair Bunker RFI Shield PSU Analog Conditioning....... Total 128 inputs 64 elements x2 polarisations Beam combiner Processor....... Output Beams 4 off Beamformer. Processors Processor Control Processor Line Tx/Rx Control Time standard Buffers From other beamformer proc. Beamformer Processing Digital Pre- processor ADC PSU Digital Pre- processor ADC..... Signal Conditioning Rack Processing Rack mini-BunkerOutdoors 64 dual channels Up to ~20m Signal conditioning module Analogue signal conditioning on replaceable mezzanine board Off-the-shelf A/D initially FPGA for data conversion and initial signal processing

11. Georgina Harris11 2-PAD 4 th SKADS Workshop, Lisbon, 2-3 October 2008 Shielded Bunker Analogue Conditioner And Sampling Rack Processor Rack 20Gb Conditioning Module Acquisition &Processing Processor Blade Processor Blade Processor Blade Processor Blade Processor Blade Processor Blade Processor Blade Processor Blade Receivers Front-end Gain. Acquisition &Processing Acquisition &Processing Acquisition &Processing Conditioning Module Conditioning Module Conditioning Module

12. Georgina Harris12 2-PAD 4 th SKADS Workshop, Lisbon, 2-3 October 2008 Power Module 2-channel signal conditioning module Clock Module 2-channel acquisition and processing module Signals from field 2 x 10Gb Links Midplane Signal conditioning

13. Georgina Harris13 2-PAD 4 th SKADS Workshop, Lisbon, 2-3 October 2008 Analogue Conditioning Board

14. Georgina Harris14 2-PAD 4 th SKADS Workshop, Lisbon, 2-3 October 2008 Analogue Conditioning Board

15. Georgina Harris15 2-PAD 4 th SKADS Workshop, Lisbon, 2-3 October 2008 DAQ Board

16. Georgina Harris16 2-PAD 4 th SKADS Workshop, Lisbon, 2-3 October 2008 DAQ Board

17. Georgina Harris17 2-PAD 4 th SKADS Workshop, Lisbon, 2-3 October 2008 2-PAD System Design +ve Reg Ant. polarisation LNA Analog Conditioning PCB Analog Twisted Pair Bunker RFI Shield PSU Analog Conditioning....... Total 128 inputs 64 elements x2 polarisations Beam combiner Processor....... Output Beams 4 off Beamformer. Processors Processor Control Processor Line Tx/Rx Control Time standard Buffers From other beamformer proc. Beamformer Processing Digital Pre- processor ADC PSU Digital Pre- processor ADC..... Signal Conditioning Rack Processing Rack mini-BunkerOutdoors 64 dual channels Up to ~20m Processing Subsystem 2-PAD Designed to enable the testing of different types of processing PrepSKA follow-on work to further investigate options

18. Georgina Harris18 2-PAD 4 th SKADS Workshop, Lisbon, 2-3 October 2008 Initial Processing for 2-PAD Cyclops processor (IBM) Cyclops blades in high-bandwidth rack 80 GFlops/blade Up to 48 blades/rack SIMD Architecture 160 thread units per chip Further Options – see Chris Shenton’s presentation

19. Georgina Harris19 2-PAD 4 th SKADS Workshop, Lisbon, 2-3 October 2008 Cyclops frame at Jodrell

20. Georgina Harris20 2-PAD 4 th SKADS Workshop, Lisbon, 2-3 October 2008 Cooling System We have a cooling system for 2-PAD which includes: A closed-loop controlled water cooling system used to cool the processor chips to keep them running at their most efficient An air conditioning system used to cool the other electronics in the bunker The two systems work together to keep the electronics at the correct temperature and humidity without compromising the RFI shielding of the bunker This cooling system will make use of ‘free’ uncooled air from outside the bunker whenever ambient temperatures permit.

21. Georgina Harris21 2-PAD 4 th SKADS Workshop, Lisbon, 2-3 October 2008 2-PAD System Design +ve Reg Ant. polarisation LNA Analog Conditioning PCB Analog Twisted Pair Bunker RFI Shield PSU Analog Conditioning....... Total 128 inputs 64 elements x2 polarisations Beam combiner Processor....... Output Beams 4 off Beamformer. Processors Processor Control Processor Line Tx/Rx Control Time standard Buffers From other beamformer proc. Beamformer Processing Digital Pre- processor ADC PSU Digital Pre- processor ADC..... Signal Conditioning Rack Processing Rack mini-BunkerOutdoors 64 dual channels Up to ~20m Bunker and Shielding RFI mitigation techniques Housing and cooling system ‘Standard’ container structure

22. Georgina Harris22 2-PAD 4 th SKADS Workshop, Lisbon, 2-3 October 2008 Processing Bunker Design The processing bunker will be manufactured to the basic pattern of a standard transport container. Dual Function: 1.Provide RFI Shielding 2.Permits the processing bunker to be filled with computers before it is shipped

23. Georgina Harris23 2-PAD 4 th SKADS Workshop, Lisbon, 2-3 October 2008 Bunker RFI shielding Connect via screened sockets Cables through tube Wrap foil along cable >60dB suppression at 1GHz, so far ARJ45 screened connectors

24. Georgina Harris24 2-PAD 4 th SKADS Workshop, Lisbon, 2-3 October 2008 Potential SKA Station Layout

25. Georgina Harris25 2-PAD 4 th SKADS Workshop, Lisbon, 2-3 October 2008 Software A highly optimised kernel and software library has been created for the Cyclops processor from scratch in Manchester A comprehensive MATLAB broadband beamforming model has been developed We have a vendor developed software simulator for the Cyclops processor and the first version single polarisation beamformer has been implemented (in the simulator environment). This is currently being validated against the MATLAB model (refer to presentation by Aziz AhmedSaid).

26. Georgina Harris26 2-PAD 4 th SKADS Workshop, Lisbon, 2-3 October 2008 2-PAD should be integrated and ready for test by Q1 2009!