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System Design choices for the SKA: Cost and performance trade-offs.

System Design choices for the SKA: Cost and performance trade-offs. Rosie Bolton, Paul Alexander, Tim Colegate, Andy Faulkner, Dominic Ford, Peter Hall and th e SKADS System Group. Outline. The SKA Cost/Performance tool Populating the tool: Hierarchical telescope design

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System Design choices for the SKA: Cost and performance trade-offs.

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  1. System Design choices for the SKA: Cost and performance trade-offs. Rosie Bolton, Paul Alexander, Tim Colegate, Andy Faulkner, Dominic Ford, Peter Hall and the SKADS System Group.

  2. Outline • The SKA Cost/Performance tool • Populating the tool: Hierarchical telescope design • Example of design block structure • Examples of some trade-offs

  3. The SKA Costing tool • Concept of “Design Blocks” was introduced in SKADS for D&C 1: Hierarchical Telescope designs made up of discrete blocks and components. • SKACost tool was developed by the ISPO (Peter Hall, Aaron Chippendale and Tim Colegate) • Initial SKADS costing based on Excel spreadsheet • The new SKA costing tool combines the best of these approaches • Advanced cost modelling and uncertainty handling (Monte Carlo) • Plug-and-play telescope designs • GUI for easy browsing and editing

  4. Overview of the tool GUI is the easiest way for non-experts to interact with telescope designs and explore cost trade-offs The engine is written in Python Design blocks are stored in portable XML format. This could be extended into a full database including other information about components Command-line Interface Graphical User Interface Socket-based Interface Python Interface Costing/Performance Tool Engine Telescope Design Data

  5. Hierarchical designs..

  6. Hierarchical designs..

  7. Hierarchical designs… Tarpaulin: cost per unit area Air con unit: cost per item Labour: cost per hour Wooden poles: cost per unit length

  8. Example: parameterised designs. • Designs are parameterised – many inputs such as collecting area, number of stations, dish diameter etc. • Tool supports “Parameter surveys” where successive telescopes can be built by varying one input parameter. This allows cost scaling to be investigated.

  9. Processing boxes in AAlo station

  10. Processing boxes in AAlo station • AA lo Station: integer number of processing boards per processing box. More boxes mean shorter analogue cables from antennas. • “Wrong” number of boxes means inefficient use of processors, so more cost. • Boxes themselves cost money. • Example is for a 90m radius station with 1.5m spaced antennas.

  11. Data link cost vs link length (16Tbit/s link) Introduction second amplifiers (160km) Introduction of first amplifiers (80km) • Large data rate link costs from tool show the combine effect of distance break points for different technologies. • These break have strong implications for cost savings if we change the layout of the Aperture Arrays Introduction of first pre-amplifiers Change from short range to mid range lasers Change from short range to mid range lasers

  12. Impact of changing the distribution • Does this matter? Yes. Look at the estimated costs for 250 AA station links, each with 16 Tbit/s. Vary Bmid – distance within which 95% of all stations are placed, cost implications of the order 100 Million EUR. • 95% within 10km, very few stations out to 180km • 95% within 100km, remainder out to 180km

  13. Impact of changing the distribution • Does this matter? Yes. Look at the estimated costs for 250 AA station links, each with 16 Tbit/s. Vary Bmid – distance within which 95% of all stations are placed, cost implications of the order 100 Million EUR. • 95% within 10km, very few stations out to 180km: data links total estimate 60M Euros • 95% within 100km, remainder out to 180km: data links total estimate 140M Euros

  14. Summary • The SKA cost/performance tool developed in SKADS and major input from an international team – flexible format designs, extensible python code. • Telescope designs can be investigated by unplugging one design block and replacing it with another. • Parameterised designs allow the impact of varying any of the inputs to be assessed – with automated output. • Currently the tool provides a useful starting point for visualising the overall system and making trade-offs. • Future work must incorporate some more book-keeping e.g. basis of estimates for cost, improved power information. • The information in the tool will fit naturally into a database, which will be essential as the SKA project moves forward.

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