SKADS System Design and Costing Update and next

SKADS System Design and Costing: Update and next steps Rosie Bolton University of Cambridge 2 nd SKADS Workshop 10 -11 October 2007 Rosie Bolton

Outline of Talk §Summary of Design and Costing work done so far: §SKADS Benchmark Scenario §Strengths and weaknesses §Next Steps 2 nd SKADS Workshop 10 -11 October 2007 Rosie Bolton

SKADS D&C work – Memo 93 • Detailed design and costing of an SKA meeting the full Benchmark Specification. 100 -300 MHz 1 -25 GHz 300 -1000 MHz Comparison of Fo. V from SKA Memo 69 and SKADS Benchmark Scenario 2 nd SKADS Workshop 10 -11 October 2007 Rosie Bolton

D&C Methodology 2 nd SKADS Workshop 10 -11 October 2007 Rosie Bolton

Overall SKA Configuration Mid Freq AA Station Proces -sing Comms links Link to Correlator freq. Dishes Core Highanalogue fibre (5 Km dia), with madelink AA antennas up of Eo. R closewith analogue link (may be close packed stations packed) Correlator in or near Core Station Desert Not to scale! 2 nd SKADS Workshop 10 -11 October 2007 Rosie Bolton

We followed the signal path: 2 nd SKADS Workshop 10 -11 October 2007 Rosie Bolton

We followed the signal path: 2 nd SKADS Workshop 10 -11 October 2007 Rosie Bolton

We followed the signal path: 2 nd SKADS Workshop 10 -11 October 2007 Rosie Bolton

We followed the signal path: 2 nd SKADS Workshop 10 -11 October 2007 Rosie Bolton

We followed the signal path: 2 nd SKADS Workshop 10 -11 October 2007 Rosie Bolton

Cost Breakdown for BS Total SKA cost breakdown Total cost: Clock, control, Correlator 7. 9% phase standard 1. 4% Mid Freq AA € 1. 91 Bn (2011) Antennas 11. 3% Mid Freq AA Comms. >480 km Analogue Data 9. 6% Transport 9. 7% Comms. <480 km 8. 1% 2 nd stage Mid Freq AA Signal processors Processing 4. 4% 15. 0% Common Station Infrastructure Mid Freq AA 1. 2% AA costs total 45% (€ 860 M) Comms. costs 18% € 340 M – with 1/9 th data rate on outer stations. Calibration source 0. 1% Mid Freq AA High Freq Dishes Infrastructure 19. 2% Extra € 500 M for full data rate. 9. 5% Low-Freq AA 2. 5% 2 nd SKADS Workshop 10 -11 October 2007 Rosie Bolton

Strengths of the Design and Costing work üCarefully considered, highly detailed design – for Mid Frequency Aperture Array. üCosting input from relevant experts (the engineers in this room): excellent to have got SKADS Engineers talking to each other. üSpeed: Excel implementation is easy for users to study, and was relatively fast to develop – five months from start of process to final document. üA very good starting point for further work … but why do we need to do more work? 2 nd SKADS Workshop 10 -11 October 2007 Rosie Bolton

Weaknesses of the Design and Costing work ûNot very flexible – difficult to change parameters: can only be done with thorough understanding of the limitations of the spreadsheet. ûOnly one SKA design was considered: e. g. single antenna arrangement for aperture array within stations. ûThe effects of station arrangement of stations over SKA area were not considered: we assumed 5 -arm log spiral. ûError analysis simplistic – all uncertainties assumed uncorrelated ûScaling with quantities to study cost / performance trade-offs graphically is not automated ûSome areas were not modelled in detail – e. g. the correlator 2 nd SKADS Workshop 10 -11 October 2007 Rosie Bolton

The Importance of the Design and Costing Work • € 1. 9 Billion is too much! • In order to get the SKA built we must find ways of reducing the system cost. • Current “acceptable” estimate would be around € 1. 5 Billion (NPV): 20% less than our Memo 93 cost. 2 nd SKADS Workshop 10 -11 October 2007 Rosie Bolton

Next Steps for D&C Effort • Central Processing to be considered in detail • Inclusion of Science requirements as a driver • Differing array designs: will mean changes in infrastructure • System temperature considerations – cost is strongly dependent on this • Cost modelling analysis 2 nd SKADS Workshop 10 -11 October 2007 Rosie Bolton

SKADS D&C in the context of the SKA • Next document to be ready early December • Updated costs: improved computing, different array layout • In time to give input into new SKA design by ISPO, early 2008 • Will enable comparison between SKA configurations and ensure that the SKADS Aperture Array work remains at the forefront of SKA design work 2 nd SKADS Workshop 10 -11 October 2007 Rosie Bolton