towards ska-low: aavs and other practicalities
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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, ... - PowerPoint PPT PresentationTRANSCRIPT
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 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
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 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)?
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