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