Rosie Bolton SKADS Workshop April 10th 2008 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 …

Rosie Bolton SKADS Workshop April 10th 2008 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

Rosie Bolton SKADS Workshop April 10th 2008 Previous SKADS costing work Benchmark scenario (old) –12, m 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)

Rosie Bolton SKADS Workshop April 10th 2008 Outline Configuration: Tiger team doc Follow concentration based on the SKA Draft specification: – DishAA-hiAA-lo –<1Km 20%30%~15% –<5Km50%66%50% –<180Km75%100%100% –<3000Km100% – 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) Station Core ~5km dia Central Processing Facility Not to scale! 180km Dishes AA-hi AA-lo

Rosie Bolton SKADS Workshop April 10th 2008 System design overview Dishes and feeds in core and in outer array 2400 dishes Dishes and feeds in core and in outer array 2400 dishes AA-lo array antennas AA Station 85 Stations, 1 AA-lo, 1 AA-hi “array” in each AA Station 85 Stations, 1 AA-lo, 1 AA-hi “array” in each Digital Signal Transport Central processing and correlator SKA First stage Analogue beam-former First stage digital beam- forming Station beam-former Analogue data transport Mechanical infrastructure AA-hi array antennas AA-hi Local digital data transport Mechanical Infrastructure Analogue data transport Digital data transport First stage digital beamforning AA-lo AA Collectors AA-hi core 165 AA-hi “arrays” AA-hi core 165 AA-hi “arrays” AA-lo core 165 AA-lo “arrays” AA-lo core 165 AA-lo “arrays” Processing boxes Infrastructure and Trenching

Rosie Bolton SKADS Workshop April 10th 2008 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 Dishes and feeds in core and in outer array 2400 dishes Digital Signal Transport SKA AA Collectors Infrastructure and Trenching System design overview Station Core ~5km dia Central Processing Facility Comms links Not to scale! 180km Dishes spread along spiral arms Dishes AA-hi AA-lo Central processing and correlator

Rosie Bolton SKADS Workshop April 10th 2008 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 Dishes and feeds in core and in outer array 2400 dishes Central processing and correlator SKA AA Collectors Infrastructure and Trenching System design overview Station Core ~5km dia Central Processing Facility Comms links Not to scale! 180km Dishes spread along spiral arms Dishes AA-hi AA-lo Digital Signal Transport

Rosie Bolton SKADS Workshop April 10th 2008 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 Digital Signal Transport Central processing and correlator SKA AA Collectors Infrastructure and Trenching System design overview Station Core ~5km dia Central Processing Facility Comms links Not to scale! 180km Dishes spread along spiral arms Dishes AA-hi AA-lo Dishes and feeds in core and in outer array 2400 dishes Dishes and feeds in core and in outer array 2400 dishes

Rosie Bolton SKADS Workshop April 10th 2008 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 Dishes and feeds in core and in outer array 2400 dishes Digital Signal Transport Central processing and correlator SKA Infrastructure and Trenching System design overview Station Core ~5km dia Central Processing Facility Comms links Not to scale! 180km Dishes spread along spiral arms Dishes AA-hi AA-lo AA Collectors

Rosie Bolton SKADS Workshop April 10th 2008 Aperture array systems AA-lo array antennas AA Station 85 Stations, 1 AA-lo, 1 AA-hi “array” in each AA Station 85 Stations, 1 AA-lo, 1 AA-hi “array” in each First stage Analogue beam-former First stage digital beam- forming Station beam-former Analogue data transport Mechanical infrastructure AA-hi array antennas AA-hi Local digital data transport Mechanical Infrastructure Analogue data transport Digital data transport First stage digital beamforming AA-lo AA Collectors AA-hi core 165 AA-hi “arrays” AA-hi core 165 AA-hi “arrays” AA-lo core 165 AA-lo “arrays” AA-lo core 165 AA-lo “arrays” Processing boxes Each AA-lo array is ~180m diameter Core may be fully-filled for improved temperature sensitivity (EoR signal) LOFAR high-band Log-Periodic dipole schematic Each AA-hi station ~60m diameter

Rosie Bolton SKADS Workshop April 10th 2008 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

Rosie Bolton SKADS Workshop April 10th 2008 Aperture array sensitivity Sensitivity averaged over scan angles out to 30º

Rosie Bolton SKADS Workshop April 10th 2008 SKA cost breakdown No: Infrastructure Roads, buildings No: Development costs NREs, tooling No: Software development costs No: Running costs No: Project management costs No: Contingency (but we do have an uncertainty estimate)

Rosie Bolton SKADS Workshop April 10th 2008 SKA cost breakdown €162 Million €394 Million €526 Million €165 Million €92 Million €63 Million €34 Million Special Offer: 1.52 Billion Euros NPV ± 31%

Rosie Bolton SKADS Workshop April 10th 2008 Scaling models: the way forward

Rosie Bolton SKADS Workshop April 10th 2008 Comms cost scaling - Dishes First, second and third amplifiers added a b c a: Cheap VCSELs can be used out to 10km fibre length RELATIVE COMMUNICATIONS COSTS BECOME MUCH MORE EXPENSIVE AFTER 50KM OF FIBRE DISTANCE FURTHER BREAK POINT AT 480KM WHERE O-E-O REGEN IS REQUIRED b: Uncooled, directly modulated lasers out to 50km c: Cooled, externally modulated lasers > 50 km

Rosie Bolton SKADS Workshop April 10th 2008 Comms cost scaling - AA Comms costs are sensitive to station placement Config work and costing work must be linked 60 million!

Rosie Bolton SKADS Workshop April 10th 2008 Cost scaling: A eff for AAs

Rosie Bolton SKADS Workshop April 10th 2008 Cost scaling: A eff for AAs Variation with scan angle due to: Projected area Element response Fixed... 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!

Rosie Bolton SKADS Workshop April 10th 2008 Scaling: complex dependencies Collector costs Data transport CorrelatorBack end computing Trenching AA Field of View  Sensitivity ( ) Tsys ( ) AA Station size  ( ) Dish size ( ) Bandwidth  Layout  Interdependencies are too complex to do with a spreadsheet: we need a more sophisticated model SKACost

Rosie Bolton SKADS Workshop April 10th 2008 Science Requirements Engineering Design & Cost The Job of PrepSKA Readiness Assessments Eng. Simulations Prototypes Pathfinders & DS Technical R&D Four Years Case Studies SKACost Courtesy Peter Dewdney

Rosie Bolton SKADS Workshop April 10th 2008 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”

Rosie Bolton SKADS Workshop April 10th 2008 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

Rosie Bolton SKADS Workshop April 10th 2008 Web-tool plug: …it’s not perfect but we are working on it, and are keen for feedback Dominic Rosie Tim Paul