Towards SKA-low: AAVS and Other Practicalities

1. Towards SKA-low: AAVS and Other Practicalities Peter Hall and Mark Waterson ICRAR/Curtin AAVP Workshop, Cambridge, 10 December 2010

2. What are the goals of AAVS? • Technology demonstrator (primarily) • Reduce risk • SKA-low ready for deployment in 2016 • Learn from LOFAR, MWA, ... • Re-invent as little as possible • Emphasize engineering • But include a focused program of science and system learning • Design validation – for (sub)systems • Does it work? • Can it be produced in quantity? • Can it be deployed cost-effectively? Fast enough? • Collaboration demonstrator • Develop culture of collaboration • Tools, processes, management, ...

3. AAVS requirements • Build functional interferometer • Validate design extensions to LOFAR, MWA • Well -defined imaging and non-imaging tests • Verify performance • Not capability (comes with adding DSP etc) • Verify scalability to SKA-low • Construction, commissioning, deployment, operation • e.g. measuring MTBF of system • Develop within institute having substantial engineering capability • AAVS will be the first dedicated SKA development! • Totally driven by SKA

4. Site impact • Ground (soil) and related issues • Finite conductivity and e.m. “mirror” • Metal ground-planes with all antenna types? • Lightning, surge considerations • Induced noise (e.g. mutual impedance coupling) • Attractiveness of galvanic isolation • Solar powered elements (PV + storage)? • Physical environment • Climate, wildlife, dust, ... • Make or break issues in design • Materials selection • Enclosure selection • Environmental conditioning (cooling, ...) • Mechanics of deployment • Low RFI – enables cost effective aperture arrays • Engineering driver: locate AAVS (mainly) at SKA site • Site must provide AAVS infrastructure and logistical support

5. ICRAR and AAVP • Moderate, but in-place resources • Euro 5M project, 25 FTE (total), € 300k capital for SKA-low prototyping • New radio astronomy engineering lab (€2M) • Explicit resources to support MRO (desert site) prototyping • Full connectivity to MRO in next 6 months • Internet access • Innovative program for SKA-low “exploratory technology” • Single antenna 70-450 MHz solution BUT in system context • Solar powered elements, low-power digital receiver and transport, galvanic isolation, .... • Major materials engineering, packaging, deployment focus • Links with mature industry partners • Development, site and logistical resources available to entire AAVP partnership

6. Power • Power is a critical issue for SKA (PITF) • AAVS can be a platform for power supply innovation • AAVS must develop a culture of power demand minimization • Design against a power budget from outset, review progress • Push low-power everywhere • RF components, DSP, data transport, control systems. ... • Investigate dynamic power management – sleep modes, “instant-on” to keep idle costs down • Collect and publish cost-benefit trade studies to educate all development groups • Most groups havelittleexperience in this but there are experts around (e.g. JPL)

7. Commercial solar powered active antenna Currently about USD 50 (1 off) (consumer AM/SW)

8. The MWA as an SKA engineering demonstrator • Proposed as a science-driven instrument but also a technology and operations demonstrator: • Base-band direct conversion • Reconfigurable backend processors (FPGA) • Enough dynamic range to ‘look between” terrestrial interference signals • Real-time calibration and beam solutions • Distributed system configuration and control • Deployment, operations and maintenance

9. Project lessons from MWA • “Basic” project management + “SE lite” not good enough in highly distributed project • The culture of a long-term project is hard to change once started • Foster common standards and project metrics from the outset • Takes time to get the tools and infrastructure of collaborative project management working • Use AAVS to ramp up to actual SKA methodologies • One “hero” PM isn’t enough, every group must be involved so that they learn how to work in a Global team • Exchange programs really work – send team members off to work at the other group’s base for 2-4 weeks, to understand the culture, resources a limitations

10. Recommendations from MWA • Lab “mock-up” is critical • Test everything before going to site • and if it doesn’t work, DON’T GO! • Enforce transparency – especially out-of-organization reviews, personnel exchanges • Separate project status reports/meetings from design workshops • Look at other data-heavy projects for development priorities – eg LHC, PanSTARRS, LSST, …

11. More specific to SKA-low • Don’t underestimate the cost of complexity • High unit counts make simple things complicated • Include studies of maintenance cost (and time) • Even a simple thing is hard if you have to do it 16 000 times! • Include real failure handling functions in designs • Ability to isolate, and turn off, malfunctioning elements at acceptably sized sections • Include transparent restart capability • Be aware of cumulative MTBFs • Analyze cumulative failure degradation carefully • How often will maintenance really be required? • What is the maintenance model (within SKA operations plan)?

12. Industry and SKA-low • Industry will make and deploy our systems • Design for manufacture, design for deployment • Combine pathfinder experience with site-knowledgeable industry know-how • Many Global industries with relevant experience • Construction and operation of remote facilities in AU, RSA • e.g. mining, resource, communications, ... • Infrastructure provision rests squarely with industry • Commissioning is where industry is most deficient • We need a commissioning plan and international commissioning crew • Constructors will not wait for leisurely sign-off large commissioning crew • Cross-disciplinary (astronomy + engineering) • Mobile (significant time at, or near, site) • Likely to grow out of AAVP team

13. Conclusion • Use Pathfinders for “active learning” • Use phased resourcing within AAVP wisely • Push for maximum SKA site-specific learning • From this point, integrate SKA-low and SKA-mid system design • Keep an open mind but require timely demonstration • Innovation important, but 2016 timescale imposes real limits • Accept that we now entering a major engineering project and be prepared to make hard decisions on specifications