SKA System Design Kobus Cloete 9 December 2010

1. "Exploring the Universe with the world's largest radio telescope" SKA System DesignKobus Cloete9 December 2010 AAVP Workshop

2. The System in Context User System Level 7 User system System Level 6 System Dish Array AA-low Infrastructure Level 5 Subsystem Dish Receiver WBSPF PAF Receptor Data links Station Processor Roads Buildings Trenching Level 4 (See full hierarchy presented as part of R. Schilizzi’s talk yesterday)

3. SKA High Level Conceptual SKA1 System Block Diagram

4. SKA Memo 125

5. Memo 125 – Summary (1) • Definition of Baseline • Low frequency sparse aperture array • Dish array • Signal transport and networks • Correlator and Non visibility processor • Central Data Processing, Science Processing and System Software. • Central timing and synchronisation subsystem, including time and frequency reference distribution, • Infrastructure (buildings, roads, facilities, labs etc.), • Power delivery and distribution, • Support and maintenance equipment and facilities

6. Memo 125 – Summary (2) • Advanced Instrumentation Program • Dense Aperture Arrays • Phased Array Feeds • Ultra Wide band Single Pixel Feeds • Decision points for AIP identified • 2016, or • As modular sub-systems of the SKA1 dishes • How do we continue with the SKA definition and design and at the same time take all of these aspects into consideration?

7. 1. How do we get to this? 2. How do we move from this ….. To this!

8. Challenges • Challenges include: • Maintaining a focus on full SKA • Definition of potential Phase 2 envelopes to ensure Phase 1 extensibility for example: • Scope of the infrastructure to be developed for Phase 1 balancing cost and Phase 2 view/extension • Selection of receptor technologies for Phase 2 in 2016 implies that the full scope, definition and design of Phase 2 will only be finalised after selection • Potentially higher costs because of wrong choices and resulting rework • Degree of integration of the AIP receptors with the Phase 1 instrument • Guard against discontinuity in buildout • Carry risks for longer

9. Route to SKA • How do we continue with the SKA definition and design and at the same time take all of these aspects into consideration? • Recently a conceptual Route to SKA was developed attempting to maintain the structure of the project but at the same time maintain flexibility to accommodate all the identified future enhancements. • Always maintain focus on the full SKA.

10. Graphical Representation (from PEP)

13. SKA1 • From the SKA1 science requirements (Memo 125) • Derive the SKA1 technical requirements • Develop initial SKA2 system technical requirements based on the science requirements contained in the Design Reference Mission (DRM). • Derive all other requirements • Perform preliminary system design for SKA1 • To be informed by early preliminary designs for the SKA2 options, so as to ensure extendibility to SKA2. • Tradeoffs of performance against cost. • Full detailed design for SKA1.

14. SKA2 • To inform the SKA1 design process • Draft initial technical requirements for the four system options for SKA2 (Baseline Technology alone + the three AIP options in combination with the Baseline Technology), • Carry out early preliminary system designs for each of the options. • Continue to track Phase 2 requirements to prepare for a decision on technology selection in 2016.

15. AIP • The AIP will build up the level of maturity in anticipation of their utilisation in SKA1 and SKA2. • General steps: • Analyse the SKA requirements to maximise potential to enhance system performance, achieve more of the initial system requirements and/or reduce cost, as compared with the baseline. • Develop a preliminary design assuming the particular AIP technology will be used at the element or subsystem level of the system. • Carry out a verification program to test the level of achievement of requirements, to develop performance/cost models for the AIP technology, and to ascertain remaining risk.

16. Requirements emanate from various sources Obsolescence Standardisation Skill level of maintainers Test equipment Simulators ….

17. Flow of requirements Science and others Requirements Top - down System Requirements Element Requirements Sub-system Comply to? Existing Solution 1 Bottom - up Existing Solution 2 New Solution

18. Process in more detail Science and other requirements Science and other requirements System System System Element 1 Element 1 Element 2 Element 2 Element 3 Element 3 Subsystem 1 Subsystem 1 CoDRs SRRs

19. (More comprehensive view) How does it all fit together? Memo 125 Time

20. Verification Programs • Example considerations: • What is the aim of the verification program? • Which requirements will be verified and how? • If not all, will a next development model be built and tested to verify these requirements? • Other considerations?

21. Where are we? • System CoDR was held in February 2010 • Provided guidance an all these aspects • Documents available at WP2 wiki: • http://www.skatelescope.org/public/2010‐02_System_CoDR_Documents/ • WP2 wiki • Memo 125 • System documents being reworked for delta CoDR in February 2011 • Will be followed by element level CoDRs during 2011 • System Requirements Review in 2012.

22. Other presentations for reference • Annual WP2 meeting (October in Oxford) • Presentations available of SKA Indico Site • Turner • Systems Methodology for the SKA • Dewdney • Refining the DRM & Deriving Technical Requirements • Cloete • System Design Plan • System Engineering Tools and Strategies • WP2 planning and Beyond PrepSKA • McCool, Hall, Bolton • Costing Strategy

23. Thank you