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

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,...

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

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

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 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

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 have little experience in this but there are experts around (e.g. JPL)

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

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

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

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, …

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 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)?

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

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