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SKADS Costing work: beyond the benchmark scenario

SKADS Costing work: beyond the benchmark scenario. Rosie Bolton Paul Alexander, Andy Faulkner and SKADS Costing tool development with Aaron Chippendale, Tim Colegate, Dominic Ford, Peter Hall and CDIT and …. Overview. SKADS costing work to date Memo 93, Benchmark scenario

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SKADS Costing work: beyond the benchmark scenario

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  1. SKADS Costing work: beyond the benchmark scenario Rosie Bolton Paul Alexander, Andy Faulkner and SKADS Costing tool development with Aaron Chippendale, Tim Colegate, Dominic Ford, Peter Hall and CDIT and …

  2. Overview • SKADS costing work to date • Memo 93, Benchmark scenario • “Second round” – Tiger Team Preliminary Specification for the SKA, costing of the SKADS “vision” for the SKA • Current / Future work: The SKA design and costing tool

  3. Previous SKADS costing work • Benchmark scenario (old) • 12,800 6.1m dishes (ATA), in dish stations • 250 Aperture array stations, co-placed with dish stations • Radius range out to 3,000km • Low frequency array costed very roughly • Reduction in data rate for longest distances (for AA), • Comms very expensive: 300 M€, +500 M€ for full data rate • Total cost ~1.9 Bn Euros (2011)

  4. Outline Configuration: Tiger team doc • Follow concentration based on the SKA Draft specification: • Dish AA-hi AA-lo • <1Km 20% 30% ~15% • <5Km 50% 66% 50% • <180Km 75% 100% 100% • <3000Km 100% • AAs only out to 180km, frequency bands 70MHz-450MHz and 300MHz-1,000MHz. AA bandwidth up to full range – set by data transfer spec • Dishes all correlated, not beam-formed in Stations. 800MHz-10GHz. B/W 4GHz • 5 spiral arms, with • 3 to 3,000km, 2 only to 180km (saves trenching cost but configuration studies must verify / challenge this) Core ~5km dia Station 180km Central Processing Facility Dishes Not to scale! AA-hi AA-lo

  5. SKA Dishes and feeds in core and in outer array 2400 dishes Central processing and correlator Digital Signal Transport AA Collectors Infrastructure and Trenching AA Station 85 Stations, 1 AA-lo, 1 AA-hi “array” in each AA-hi core 165 AA-hi “arrays” AA-lo core 165 AA-lo “arrays” Station beam-former AA-lo AA-hi First stage Analogue beam-former First stage digital beam-forming AA-hi array antennas AA-lo array antennas First stage digital beamforning Digital data transport Analogue data transport Mechanical infrastructure Local digital data transport Mechanical Infrastructure Analogue data transport Processing boxes System design overview

  6. System design overview SKA • Central Processing Facility • Correlator • Back-end computing • Some station beamforming for AA-lo core Dishes and feeds in core and in outer array 2400 dishes Central processing and correlator Digital Signal Transport AA Collectors Infrastructure and Trenching Comms links Dishes spread along spiral arms Core ~5km dia Station 180km Central Processing Facility Dishes Not to scale! AA-hi AA-lo

  7. System design overview SKA • Digital Signal Transport • Detailed model for Communications • Technology choice dependent on link length and data rate • Development work in progress within SKADS (Roshene McCool and others) Dishes and feeds in core and in outer array 2400 dishes Central processing and correlator Digital Signal Transport AA Collectors Infrastructure and Trenching Comms links Dishes spread along spiral arms Core ~5km dia Station 180km Central Processing Facility Dishes Not to scale! AA-hi AA-lo

  8. System design overview SKA • Dishes • 15m (in line with Tiger Team Spec) • Costed from SKAcost • Cost of dish and feed • €200,000 NPV per dish • 2,400 dishes • Range Dishes and feeds in core and in outer array 2400 dishes Central processing and correlator Digital Signal Transport AA Collectors Infrastructure and Trenching Comms links Dishes spread along spiral arms Core ~5km dia Station 180km Central Processing Facility Dishes Not to scale! AA-hi AA-lo

  9. System design overview SKA • AA collectors are SKADS focuses – especially the AA-hi (300-1,000MHz) • AA collectors sit in central cores (AA-lo and AA-hi separately) and in outer stations (together) Dishes and feeds in core and in outer array 2400 dishes Central processing and correlator Digital Signal Transport AA Collectors Infrastructure and Trenching Comms links Dishes spread along spiral arms Core ~5km dia Station 180km Central Processing Facility Dishes Not to scale! AA-hi AA-lo

  10. AA Collectors AA Station 85 Stations, 1 AA-lo, 1 AA-hi “array” in each AA-hi core 165 AA-hi “arrays” AA-lo core 165 AA-lo “arrays” Station beam-former LOFAR high-band AA-lo AA-hi Log-Periodic dipole schematic First stage Analogue beam-former First stage digital beam-forming AA-hi array antennas AA-lo array antennas First stage digital beamforming Digital data transport Each AA-lo array is ~180m diameter Core may be fully-filled for improved temperature sensitivity (EoR signal) Analogue data transport Mechanical infrastructure Local digital data transport Mechanical Infrastructure Analogue data transport Processing boxes Each AA-hi station ~60m diameter Aperture array systems

  11. Costed Data Rates • AA-hi Data rate equivalent to 250 square degrees across the whole band from 300 MHZ to 1,000 MHz. Including 8:10 encoding, 16.5 Tb/s per station • AA-lo Data rate equivalent to 200 square degrees across the band from 70 MHz to 450 MHz, 12.5 Tb/s • Complete flexibility in the beams that are sent back • Increase field of view (more beams on the sky) • Decrease the bandwidth

  12. Aperture array sensitivity Sensitivity averaged over scan angles out to 30º

  13. No: Infrastructure Roads, buildings No: Development costs NREs, tooling No: Software development costs No: Project management costs No: Contingency No: Running costs SKA cost breakdown (but we do have an uncertainty estimate)

  14. SKA cost breakdown €34 Million €63 Million €92 Million €162 Million Special Offer: 1.52 Billion Euros NPV ± 31% €165 Million €394 Million €526 Million

  15. Scaling models: the way forward

  16. RELATIVE COMMUNICATIONS COSTS BECOME MUCH MORE EXPENSIVE AFTER 50KM OF FIBRE DISTANCE FURTHER BREAK POINT AT 480KM WHERE O-E-O REGEN IS REQUIRED Comms cost scaling - Dishes c a b First, second and third amplifiers added a: Cheap VCSELs can be used out to 10km fibre length b: Uncooled, directly modulated lasers out to 50km c: Cooled, externally modulated lasers > 50 km

  17. Comms cost scaling - AA Comms costs are sensitive to station placement Config work and costing work must be linked 60 million!

  18. Cost scaling: Aeff for AAs

  19. Cost scaling: Aeff for AAs • Variation with scan angle due to: • Projected area • Element response • Fixed <Aeff> ... Amount of collecting area required is a strong function of scan angle requirement: change 30 deg to 45 deg, need 40% more collector: extra ~500 million Euros!

  20. Scaling: complex dependencies Interdependencies are too complex to do with a spreadsheet: we need a more sophisticated model SKACost

  21. The Job of PrepSKA Science Requirements Case Studies Eng. Simulations Four Years Prototypes Pathfinders & DS Technical R&D SKACost Readiness Assessments Courtesy Peter Dewdney Engineering Design & Cost

  22. Future work: • SKADS AA model is already scalable on a broad level • Collecting area requirements • Bandwidth • FoV • Needs more work to make fine details scale: • Operating frequency / Antenna spacing requirements • Station layout / Configuration • AA-lo: further design work required for low-freq antennas • Analogue beamforming / Digital beam-forming • SKACost costing tool is essential for this • SKACost will be used by selection committee to further define the SKA spec • Important that all technologies are adequately represented in SKACost • Need a shift in approach towards a “model”

  23. Future work: • SKACost developments will include: • Improved web-tool, with AA costing, in near-term future • End-August distribution of GUI-based tool • Help required to test this tool - contact us! (Me, Tim Colegate, Dominic Ford, Aaron Chippendale, Peter Hall, Paul Alexander) • The better the tool is a describing the technology, the better the merits of that option will show up. • Longer-term flexible GUI-based tool allowing design blocks and components to be created and an SKA designed from a shopping basket of sub-components

  24. Web-tool plug: http://www.atnf.csiro.au/projects/ska/cost/ …it’s not perfect but we are working on it, and are keen for feedback Paul Rosie Dominic Tim

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