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Engineering Overview

Engineering Overview. Andrew Faulkner. Engineering Aims. From Science simulation specifications (DS2 T1) : Simulate the performance for the overall SKA, (DS2 T2) Optimise SKA architecture through simulation (DS3 T3) Prove a mid-frequency, 0.3-1.0 GHz, Aperture Array:

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Engineering Overview

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  1. Engineering Overview Andrew Faulkner

  2. Engineering Aims From Science simulation specifications (DS2 T1): • Simulate the performance for the overall SKA, (DS2 T2) • Optimise SKA architecture through simulation (DS3 T3) • Prove a mid-frequency, 0.3-1.0 GHz, Aperture Array: • Operation, collector cost and radio-astronomy demonstrator (DS5) • Develop components & sub-systems (DS3 T1, 2; DS4 T1-5, DS6) • Build small, high-performance demonstrator (DS4 T6) • Produce costed design for SKA (DS8)with ISPO SKADS Workshop 2006

  3. A start-up year..... • Patchy progress by country, primarily due to funding • Teams being built up or in place • Considerable thought on system issues • Relationship with Reference Design (memo 69) • Some evolution of system ideas Details by DS Later SKADS Workshop 2006

  4. Communications • Significant meetings: • EMBRACE & BEST ongoing project meetings • ‘Technical’ Meeting: Scientists + Engineers • Simulation Meeting: DS2-T2 + DS3-T3 • Kick-offs: • DS2-T1 Science Simulation • DS3-T1 Data Transport + Phase Transfer • DS4-T1, T2+T3, T4 Front-end; RFI+Digitisation; Antenna • Wiki Site for Project communications and interaction • www.skads-eu.org  wikis • Email Exploder + Archiving (see wiki) SKADS Workshop 2006

  5. The Netherlands Early start, EMBRACE ~on schedule Excellent participation UK Slow start, due to Finance delay Major recruitment programmes System config. by academics France Engineers in place, working on EMBRACE Kick-off DS4-T3 Italy BEST1 going well BEST2 projected 2Q2007 Rx for EMBRACE underway Spain Engineers in place Participating DS4-T4 Initial work completed & reported Other Participants SA: KAT Australia: xNTD Canada: PHAD Country Progress } Underway and active SKADS Workshop 2006

  6. Despite slow start-up: SKADSis Targeted to Finish on time Crucial for International SKA timeline.... SKADS Workshop 2006

  7. SKADS‘Benchmark’ design Kickoffs and System discussions Show the need for a Starting Specification... SKADS Workshop 2006

  8. We need a target specification now to ‘aim’ at, for: • Scientists in DS2-T1 to simulate their observations • Technical and network simulations in DS2-T2 and DS3-T3 • Engineers to realistically design to and evaluate • Early costing..... ‘Benchmark’ Specification This will be the basis to evolve the final spec. SKADS Workshop 2006

  9. Do we believe that Aperture Arrays will be the ONLY collecting area over a frequency band? • Ability to image • Dynamic range etc • What is the TOP frequency we are planning foran Aperture Array? Firstly, two questions.... SKADS Workshop 2006

  10. Cost viability of AA critically dependent on top freq. e.g. cost for Nyquist sampled 1.0 GHz < 50% cost for 1.4 GHz!! Top Frequency.... The cost of a close packed aperture array varies as: Cost ≈freq2+ε+ infrastructure BUT: MUST support the science! • Top freq2due to linear pitch is ~λ/2 • εdue to additional bandwidth and higher cost ADC and analogue parts etc. (0→1) • Infrastructure is relatively low cost SKADS Workshop 2006

  11. SKA Reference Design LOFAR, MWA etc. AA duplicates freq. EOR AA All Sky AA ~10m Dishes FPA ~10m Dishes WBF 0.1 0.3 1.0 3.0 10.0 30.0 GHz ≥ 10m for 300 MHz FPA for FOV How to switch w/very large FPA? Assuming we have confidence in AA.... SKADS Workshop 2006

  12. AA fully used AA a critical part of SKA: Large FOV, excellent at low freq EOR AA Mid-Freq AA ~10m Dishes FPA ~6m Dishes WBF Not required?! 0.1 0.3 1.0 3.0 10.0 30.0 GHz 6m dish: larger natural FOV easier hi-freq, ‘cheap’ SKADS Workshop 2006

  13. FOV specification EOR AA: 200 deg2 10m Dish + FPA-2: 5 deg2 10m Dish + WBF (1.4/f)2 deg2 10m Dish + FPA-1: 50 deg2 SKADS Workshop 2006

  14. FOV specification EOR AA: 200 deg2 Mid AA: 250 deg2 6m Dish + WBF 3*(1.4/f)2 deg2 At 1.4GHz ... Ref: 5 deg2 B’mark: ~4 deg2 SKADS Workshop 2006

  15. Further Notes • 300-500 MHz is a problem: • Dishes perform less well at low frequencies • Sky noise is increasing, which needs bigger collecting area • Consider frequency dependant AA: more collecting area at lower frequencies <500MHz. • Consider allowing >1.0 GHz (1.2 GHz?) with grating lobes on AA. • Are there any ‘low cost’ 10+m dishes? • 6m dish design will be proven by ATA • No consideration has yet given to multiple beams or very large (>500 deg2) FOVs to trade with sensitivity • WBFs will be proven (0.5-11 GHz): modify for 0.9-25 GHz? SKADS Workshop 2006

  16. Some perceived issues with AA • Community skepticism on cost and performance • Limited scan angle range: ±45° to ±60° (dishes may be < ±90°) • Geometrically reducing aperture with scan angle • Quality of beam formation • Effects of strong sources anywhere in the sky • Sources in the sidelobes SKADS Workshop 2006

  17. SKADS will .... Use two SKA Specifications for Simulations and Costing (Engineering will only R & D the Benchmark Design): • Reference Design • EOR Aperture Array • Fish-eye lens AA 0.3 – 1.0 GHz • 10m dish + • FPA1 0.3 – 1.0 GHz • FPA2 1.0 -3.0 GHz • WBF 3.0 – 25 GHz • SKADS Benchmark • EOR Aperture Array • Mid-freq AA 0.3 – 1.0 GHz • 6m dish + • WBF 0.9 – 25 GHz Compare: Science capability + Cost information SKADS Workshop 2006

  18. ‘Fleshed out’ Specifications based on SKA memos are on the WIKI Please put up comments on-line! Over to the Science...... SKADS Workshop 2006

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