SA Bursary Conference December 2009 SKA Design. SA Bursary Conference December 2009 SKA Design Designing an optimal SKA around AAs at low frequencies.

SA Bursary Conference December 2009 SKA Design

SA Bursary Conference December 2009 SKA Design Designing an optimal SKA around AAs at low frequencies plus dishes at higher frequencies – maximising the science output for a fixed cost

SA Bursary Conference December 2009 SKA Design.. Sparse AA Dense AA.. Mass Storage TimeStandard Central Processing Facility - CPF User interface via Internet... To 250 AA Stations... DSP... DSP To 2400 Dishes... 12-15m Dishes Correlator – AA & Dish 16 Tb/s 80 Gb/s Control Processors & User interface Post Processor Data Time Control 70-450 MHz Wide FoV 0.4-1.4 GHz Wide FoV 0.8-10 GHz Single Pixel or Focal plane array Tile & Station Processing SKA Overall Structure

SA Bursary Conference December 2009 SKA Design Potential Configuration: AA Station Core ~5km dia Central Processing Facility Comms links Not to scale! 180km Dishes spread along spiral Dishes AA-hi AA-lo ~250 Aperture array stations ~2400 Dishes

SA Bursary Conference December 2009 SKA Design Parameter name UnitRange, Value or Calculation Remarks PAF:ν L MHz500 – 1000 Lower operational frequency for PAF. PAF:ν H MHz1500 – 2000 Maximum operational frequency for PAF. PAF:Δν Max MHz700 Maximum instantaneous bandwidth for PAF. PAF:ν Nyq MHz Calculated: =PAF:ν H Frequency at which PAF antennas are half- wavelength spaced. PAF:T rec K30-60 Receiver temperature for PAF receivers. PAF:η ap %55-70 Aperture efficiency for the PAFs when placed on the dishes. PAF:A geom (ν Nyq ) m2m2 Calculated from dish distribution and aperture efficiency Total effective area for all the Dishes with PAFS together. PAF:B max km0 - 500 Maximum baseline (from core) for PAFs. All dishes within this distance are assumed to have a PAF and a WBSPF on them, therefore this parameter determines how many dishes have PAFs. PAF:N b,max #40 Maximum number of beams required from the PAF. PAF:FTb/s0-Max Data rate output from PAF. Some SKA design parameters..... Parameter name UnitRange, Value or Calculation Remarks AAlo:F Stn Tb/s0-100 Data rate transported from each station. AAlo:ν L MHz70-200 Lower frequency of operation for AAlo. Variable only if we wish to have multiple AAlo element types. AAlo:ν H MHz200 - 450 Highest frequency of operation for AAlo AAlo:ν Nyq MHz100 - 300 Nyquist frequency for AAlo elements. This will be used to determine the element size (half- wavelength at ν Nyq ), and may differ if we use multiple AAlo element types. AAlo:Δν Max MHz calculated: AAlo:ν H  AAlo:ν L AAlo will be capable of using the full frequency range. AAlo:T rec (ν)K calculated: (50, 0.1xT sky (ν)) This must be low enough to be unimportant compared to sky noise, but with a limit of 50K AAlo:A geom (ν Ny q ) m2m2 2-10 x 10 6 This is the geometric footprint of the all the antennas – which will be smaller than the area enclosed within a station’s perimeter if the antennas have been sparsed with a filling factor (see below). This quantity is directly proportional to the number of antennas, regardless of any filling factor. AAlo:ff%50-100 AAlo filling factor: a value of 80% would denote that only 80% of the area within a station’s perimeter is taken up with antenna footprints. AAlo:N#50 - 350 The number of AAlo stations in total. All are assumed to be the same size. AAlo:D Stn m calculated: π×D Stn 2 /4=A geom /(ff×N) The diameter of each AAlo station. This is calculated from the geometric area of antennas, the filling factor and the number of stations. Need to check this against constraints from calibration. AAlo:f core %67 The fraction of AAlo collectors which are within the close-packed core. AAlo:D core km calculated: π×D core 2 /4=(A geom × f core )/(ff×0.91) The diameter of the close-packed core. Calculated, assuming a station packing density of 91% within the core (theoretical max for abutting circles). AAlo:B max kmD core /2 - 400 The maximum baseline (distance from core) that the AAlo stations are placed out to. AAlo:B mid kmD core /2 - 100 Break baseline (radius) for AAlo distribution. AAlo:f mid %95 Fraction of AAlo collectors within B mid. AAlo:η ap %80 The aperture efficiency for the AAlo antennas. Taken as fixed for now – we will use values from LOFAR, but ultimately this will depend on the antenna design. AAlo:S(ν)m 2 /Kcalculated Calculated sensitivity of the AAlo collectors, as a whole. AAlo:BpS#2-8 Bits per Sample for the AAlo data. Parameter nameUnitRange, Value or Calculation Remarks AAhi:F Stn Tb/s0-100 Data rate transported from each station. AAhi:ν L MHz Minimum operational frequency for AAhi AAhi:ν H MHz 1000 – 3000 (AA only) 700 – 1450 (for SKA designs with Dishes) Maximum operational frequency for AAhi. The range of values needed depends upon the telescope being designed: for the AA-only telescope we will need to model the costs of an Aperture array that can perform at high frequency (up to 3GHz), whilst for the SKA designs which include dishes with SPFs/PAFs we will not need to consider such high operational frequencies for the AAhi as they will be covered by these other receivers. AAhi:ν Nyq MHz calculated: 0.7×AAhi:ν H Frequency at which AAhi antennas meet Nyquist sampling criterion. AAhi:Δν Max MHz700 Maximum instantaneous bandwidth for AAhi. AAhi:T rec K30-60 Receiver temperature for AAhi antennas. AAhi:A geom (ν Nyq ) m2m2 0-10 x 10 5 Total effective area, on boresight and at AAhi:ν Nyq for all the AAhi stations together. AAhi:D Stn m calculated: π×D Stn 2 /4=A geom /(N) Diameter of each AAhi station (assumed to all be the same) AAhi:f core %67 Fraction of the AAhi collectors that are within the core. AAhi:D core km calculated: π×D core 2 /4=(A geom × f core )/0.91 Diameter of the core for the AAhi. Calculated from collecting area and core fraction assuming close-packing circles. AAhi:B max kmD core /2 - 500 Maximum baseline (from core) for AAhi. AAhi:N#150 - 350 Number of AAhi stations. AAhi:B mid km10 - 100 Baseline (radius) of AAhi distribution break. AAhi:f mid %95 Fraction of total AAhi collectors within B mid. AAhi:BpS#2-8 Bits per Sample for the AAhi data. AAhi:RF input #1-25 Number of RF inputs into analogue beam-forming unit (see Figure 1). AAhi:RF output #1-AAhi:RF input Number of RF beams output from analogue beamforming unit (see Figure 1). Parameter nameUnitRange, Value or Calculation Remarks DISH:Dm6-25 Dish diameter. DISH:f core %50 The fraction of Dishes that are within the core. DISH:D core kmcalculated The diameter of the core. The core is assumed to be close-packed with its size determined by shadowing requirements and the number of dishes in the core, which is determined from the core fraction. DISH:B max km3000 The maximum baseline (distance from core) that dishes are placed out to. DISH:B mid km100 - 500 Break distance for dish distribution (see next). DISH:f mid %75 Fraction of dishes that are within the B mid distance (including the fraction in the core). DISH:A eff m2m2 0-10 x 10 5 Total effective area of the all the dishes. Parameter name Unit Range, Value or Calculation Remarks SPF:ν L MHz Lowest frequency of operation for the Wide- band feeds. SPF:ν H MHz10,000 Highest frequency of operation for the Wide-band feeds. SPF:Δν Max GHz1-8 Maximum instantaneous bandwidth for the Wide-band feeds. SPF:T rec K15-50 Receiver temperature for the Wide-band feeds (no consideration will be taken of how this varies across the band). This range needs to be checked against current international expectations. SPF:η ap %55-70 Aperture efficiency for the Wide-band feeds when placed on the dishes.

SA Bursary Conference December 2009 SKA Design SKA implementation analysis Instrument Technical Specification: Sensitivity Survey speed Configuration Stability Potential Designs: Collector type Frequency range Data rates etc Operational Constraints: Time allocation Storage Power Operations budget Physical Parameters: Flux Area of sky Polarisation Dynamic range etc KeyScienceExperiments SKADesign Modelling: Variants Performance Cost Power Risk

SA Bursary Conference December 2009 SKA Design Science Requirements.... http://www.skatelescope.org/PDF/091001_DRM_v0.4.pdf

SA Bursary Conference December 2009 SKA Design Design Reference Mission 2. Resolving AGN and Star Formation in Galaxies 3. Pre-biotic molecules in and around Protoplanetary Disks 4. Cosmic Magnetism Deep Field Component 5. Wide Field Polarimetry 6. Tracking Cosmic Star Formation: Continuum Deep Field 7. Neutral Gas in Galaxies: Deep HI Field 8. Epoch of Reionization HI Imaging Tomography 9. Spacetime Env. of the Galactic Center with Radio Pulsars 10a. Theories of Gravity using Ultra-relativistic Binaries: Survey 13a. Pulsar Timing Array for Gravitational Wave Study: Survey 10b. Theories of Gravity using Ultra-relativistic Binaries: Timing 13b. Pulsar Timing Array for Gravitational Wave Study: Timing 11. Galaxy Evolution over Cosmic Time via H I Absorption 12. H I Baryon Acoustic Oscillations 14a. Exploration of the Unknown: The Transient Radio Sky 14b. Exploration of the Unknown: The Transient Radio Sky 15. Probing AGN via HI absorption Science Experiments

SA Bursary Conference December 2009 SKA Design 0 2,500 5,000 7,500 10,000 Sensitivity A eff /T sys m 2 K −1 0.31.03.010.0 Frequency GHz 0.10.141.4 2. Resolving AGN and Star Formation in Galaxies 39,000 5. Wide Field Polarimetry - 2 11. Galaxy Evolution via H I Absorption 12. HI BAO 3. Protoplanetary disks 6. Continuum deep field 7. Deep HI Field 9. Galactic centre pulsars 10a, 13a. Pulsar search 10b, 13b. Pulsar timing 4. Cosmic Magnetism 8. HI EoR Sensitivity Requirements 12,500 15,000 Specified sensitivity Derived from survey speed 5. Wide Field Polarimetry - 1 Huge.... DRM 0.4 15. Probing AGN via HI abs’n

SA Bursary Conference December 2009 SKA Design 1e2 1e4 1e6 1e8 1e10 Survey Speed m 4 K −2 deg 2 0.31.03.010.0 Frequency GHz 0.10.141.4 2. Resolving AGN & Star Form’n 5. Wide Field Polarimetry 11. Galaxy Ev. via HI Abs’n 12. HI BAO 3. Protoplanetary disks 7. Deep HI Field 9. Galactic centre pulsars 10b, 13b. Pulsar timing 4. Cosmic Magnetism 8. HI EoR Survey Speed Requirements 1e1 Specified survey speed Derived from sensitivity 13a. Pulsar search DRM 0.4 6. Continuum deep field

SA Bursary Conference December 2009 SKA Design 10 30 100 300 1,000 Baseline length, k m 0.31.03.010.0 Frequency GHz 0.10.141.4 >3000 2. Resolving AGN and Star Formation in Galaxies 5. Wide Field Polarimetry 11. Galaxy Evolution via HI Absorption 12. HI BAO 3. Protoplanetary disks 6. Continuum deep field 7. Deep HI Field 9. Galactic centre pulsars 10a, 13a. Pulsar search 10b, 13b. Pulsar timing 4. Cosmic Magnetism 8. HI EoR Baseline Requirements 3 1 Stated in DRM Unstated in DRM - assumed DRM 0.4 3000 15. Probing AGN via HI abs’n

SA Bursary Conference December 2009 SKA Design Comments on Science reqts Major surveys are <1.4 GHz: below HI line Only AGN experiments are >500km baseline Interesting how many want 10,000 m 2 /K...... Continuum & Pulsars want as much sensitivity as possible Transients requirements are not shown Would like the parameters as a function of frequency

SA Bursary Conference December 2009 SKA Design Some design trade-offs...... trade-offs......

SA Bursary Conference December 2009 SKA Design Tailoring the AA system 100 10 1 100 1000 Frequency (MHz) Sky Brightness Temperature (K) A eff A eff /T sys Fully sampled AA-hi Sparse AA-lo T sky Becoming sparse A eff / T sys (m 2 / K) AA frequency overlap Dish operation f AA f max

SA Bursary Conference December 2009 SKA Design Ae ….. Tile Processor - hi TH_0 TH_1 TH_n ….. Tile Processor - lo TL_0 TL_1 TL_m Station Processor 0 e/o ….. o/e ……. e/o Station Processor n ……. Long distance drivers ….. o/e e/o Long distance drivers ….. Long distance drivers …...... ….. 1.0-1.4GHz analogue 1.0 GHz analogue 12 fibre lanes @10Gb/s each ………... 12 fibre lanes @10Gb/s each 10Gb/s fibre ….. Max 4 Station Processors Local Processing e.g. Cal; pulsars To Correlator Inputs #: 1296 Channel rate:120Gb/s (raw) Total i/p rate:1.5 Pb/s Typical: AA-hi tiles:300 AA-lo tiles:45 Total:345 I/p data rate:42Tb/s Notes: 1. No control network shown 2. Up to 4 station processor systems can be implemented in parallel 3. Data shown are raw, typ. get 80% data ….. AA Station Configuration

SA Bursary Conference December 2009 SKA Design AA Station performance costs Cost for Field of View, FoV: 10% Cost for A eff /T sys : 90% Sensitivity: A eff /T sys Survey Speed:(A eff /T sys ) 2 x FoV

SA Bursary Conference December 2009 SKA Design Frequency AA – Dish Frequency X-over Dish+feedAA Cost increases as f top 2 Can reduce A eff at high f Cover main survey reqts. low f low implies large dia. Large feed for low freq Costs high for low freq

SA Bursary Conference December 2009 SKA Design Central Processing Facility

SA Bursary Conference December 2009 SKA Design Central Processing Facility... AA slice... AA slice... AA slice... Dish & AA+Dish Correlation...... ProcessorBuffer ProcessorBuffer ProcessorBuffer ProcessorBuffer ProcessorBuffer ProcessorBuffer ProcessorBuffer ProcessorBuffer ProcessorBuffer ProcessorBuffer ProcessorBuffer ProcessorBuffer ProcessorBuffer ProcessorBuffer ProcessorBuffer ProcessorBuffer ProcessorBuffer ProcessorBuffer ProcessorBuffer ProcessorBuffer ProcessorBuffer ProcessorBuffer Data switch...... AA Stations Dishes Data Archive ScienceProcessors Correlator UV Processors Image formation Science analysis, user interface & archive BeamsVisibilitiesUV dataImages 250 x 16Tb/s ~4.8 Pb/s 2400 x 80Gb/s Tb/sGb/s Pb/s... Imaging Processors ~10 Pflop

SA Bursary Conference December 2009 SKA Design The central processing problem….. Data rate, R, from the correlator Each pair of antennas are multiplied togetherR  N c 2 For each beamR  N b Must avoid chromatic aberration – need to split bandwidth  f into N ch channels of width  f < f D / BR  f /  f Longest integration time must sample changing sky due to rotation of the earth  t < 2600  max /  D R  1 /  t Linear for no. of beams Quadratic for no. of collectors Quadratic for baseline length Inverse Quadratic for collector diameter

SA Bursary Conference December 2009 SKA Design The central processing problem….. Data rate, R, from the correlator Each pair of antennas are multiplied togetherR  N c 2 For each beamR  N b Must avoid chromatic aberration – need to split bandwidth  f into N ch channels of width  f < f D / BR  f /  f Longest integration time must sample changing sky due to rotation of the earth  t < 2600  max /  D R  1 /  t Linear for no. of beams Quadratic for no. of collectors Quadratic for baseline length Inverse Quadratic for collector diameter Processing cost.... N b  FoV: cheap B  resolution:expensive D -1  FoV:very expensive Fewer big stations + more beams is much cheaper

SA Bursary Conference December 2009 SKA Design Data rates out of Correlator Experiment3000 Dishes + SPF250 AA stations Description B max (km) Δf (MHz) f max (MHz) Achieved FoVData rate (Tb/s) Achieved FoV 1 Data rate (Tb/s) Survey: High surface brightness continuum 570014000.780.0551080.03 Survey: Nearby HI high res. 32000 channels 570014000.781.01082.6 Survey: Medium spectral resolution; resolved imaging (8000) 3070014000.781.21085.4 Survey: Medium resolution continuum 18070014000.7833.110814.1 Pointed: Medium resolution continuum deep observation 18070014000.7833.10.780.15 High resolution with station beam forming 2 1000200080000.001533.4 High resolution without station beam forming 3 1000200080000.0015429 Highest resolution for deep imaging 2 30004000100000.001391 1.For the AA the data rate assumes constant FoV across the band. 2.Assuming that for the dynamic range the FoV of the station only has to be imaged 3.Assuming that for the dynamic range the FoV of the dish must be imaged

SA Bursary Conference December 2009 SKA Design Processing model

SA Bursary Conference December 2009 SKA Design Model for UV processor Highly parallel – 20 TFlop promised in 2 years – assume 50 Tflop in 2018 Operations/sample reqd.: ~20,000/calibration loop Processor: €1000, 5 calibration loops, 50% efficiency, Each processor can operate on ~ 1 GB/s of data Requirement: 100 PFlop (AA)2 EFlop (dishes) Buffer 1 hr of data  7.2 TB in a fast store Memory est. €200 per TB. Total UV-processing : Cost = €2.5m per TB/s AA< €10m Dishes ~ €125m ProcessorBuffer ProcessorBuffer ProcessorBuffer ProcessorBuffer ProcessorBuffer ProcessorBuffer ProcessorBuffer ProcessorBuffer ProcessorBuffer ProcessorBuffer ProcessorBuffer ProcessorBuffer ProcessorBuffer ProcessorBuffer ProcessorBuffer ProcessorBuffer ProcessorBuffer ProcessorBuffer ProcessorBuffer ProcessorBuffer ProcessorBuffer ProcessorBuffer...... UV Processors UV data Gb/s

SA Bursary Conference December 2009 SKA Design From Bruce Elmegreen, IBM Technology Roadmapping

SA Bursary Conference December 2009 SKA Design Modelling: Design and Costing Tool Also tracks Power & data rate

SA Bursary Conference December 2009 SKA Design Hierarchical designs..

SA Bursary Conference December 2009 SKA Design Data link cost vs length (16Tbit/s) 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 Change from short range to mid range lasers Introduction of first pre- amplifiers Change from short range to mid range lasers Introduction of first amplifiers (80km) Introduction second amplifiers (160km)

SA Bursary Conference December 2009 SKA Design Changing the collector 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

SA Bursary Conference December 2009 SKA Design 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: 60M Euros 95% within 100km, remainder out to 180km: 140M Euros

SA Bursary Conference December 2009 SKA Design Consider a possible SKA....

SA Bursary Conference December 2009 SKA Design 0 2,500 5,000 7,500 10,000 Sensitivity A eff /T sys m 2 K −1 0.31.03.010.0 Frequency GHz 0.10.141.4 2. Resolving AGN and Star Formation in Galaxies 39,000 5. Wide Field Polarimetry - 2 11. Galaxy Evolution via H I Absorption 12. HI BAO 3. Protoplanetary disks 6. Continuum deep field 7. Deep HI Field 9. Galactic centre pulsars 10a, 13a. Pulsar search 10b, 13b. Pulsar timing 4. Cosmic Magnetism 8. HI EoR Sensitivity Requirements 12,500 15,000 Specified sensitivity Derived from survey speed 5. Wide Field Polarimetry - 1 Huge.... DRM 0.4 15. Probing AGN via HI abs’n AA-lo AA-hi Dish Can this reqt. be 5000 m 2 K -1 ? This reqt. is ~16 Km 2 AA!!

SA Bursary Conference December 2009 SKA Design 1e2 1e4 1e6 1e8 1e10 Survey Speed m 4 K −2 deg 2 0.31.03.010.0 Frequency GHz 0.10.141.4 2. Resolving AGN & Star Form’n 5. Wide Field Polarimetry 11. Galaxy Ev. via HI Abs’n 12. HI BAO 3. Protoplanetary disks 7. Deep HI Field 9. Galactic centre pulsars 10b, 13b. Pulsar timing 4. Cosmic Magnetism 8. HI EoR Survey Speed Requirements 1e1 Specified survey speed Derived from sensitivity 13a. Pulsar search DRM 0.4 6. Continuum deep field AA-lo AA-hi Dish Does the science require this?

SA Bursary Conference December 2009 SKA Design 10 30 100 300 1,000 Baseline length, k m 0.31.03.010.0 Frequency GHz 0.10.141.4 >3000 2. Resolving AGN and Star Formation in Galaxies 5. Wide Field Polarimetry 11. Galaxy Evolution via HI Absorption 12. HI BAO 3. Protoplanetary disks 6. Continuum deep field 7. Deep HI Field 9. Galactic centre pulsars 10a, 13a. Pulsar search 10b, 13b. Pulsar timing 4. Cosmic Magnetism 8. HI EoR Baseline Requirements 3 1 Stated in DRM Unstated in DRM - assumed DRM 0.4 3000 15. Probing AGN via HI abs’n AA-lo AA-hi Dish These baselines are very expensive! Fibre & computing A few large low freq dishes?

SA Bursary Conference December 2009 SKA Design SKACost Remarks QuantityEachTotal € 2011 NPV Aperture Arrays: AA-hi arrays2501,467,065366,766,150165 core and 85 outer arrays AA-lo arrays250648,876162,218,926 Station processors 250227,00456,750,988Processing for station beamforming Total AA585,736,064 Dishes: Antenna + feed1200219,175263,010,000 Includes Antenna, feed, electronics and cooling Total dish263,010,000 Communication s: AA core64,313,900 AA outer57,951,575 Dishes28,130,166 Trenching - all92,457,741 Total comms242,853,382 Central Processing Includes control and clock distribution Correlator62,749,341 Includes correlation facilities for both AA and dish collectors Post processing34,000,000Includes processing and storage Clock distribution9,263,217 Total central proc. 106,012,558 Total SKA1,197,612,004 Costs for ‘this’ SKA Costs not Included: Development work Non-recoverable expenses Civil works Power installation Operational Costs Project Management Collectors 250 x 57m dia AA-hi 250x220m dia AA-lo 1200 x 15m dishes Wideband SPFeeds

SA Bursary Conference December 2009 SKA Design SKACost Remarks QuantityEachTotal € 2011 NPV Aperture Arrays: AA-hi arrays2501,467,065366,766,150165 core and 85 outer arrays AA-lo arrays250648,876162,218,926 Station processors 250227,00456,750,988Processing for station beamforming Total AA585,736,064 Dishes: Antenna + feed1200219,175263,010,000 Includes Antenna, feed, electronics and cooling Total dish263,010,000 Communication s: AA core64,313,900 AA outer57,951,575 Dishes28,130,166 Trenching - all92,457,741 Total comms242,853,382 Central Processing Includes control and clock distribution Correlator62,749,341 Includes correlation facilities for both AA and dish collectors Post processing34,000,000Includes processing and storage Clock distribution9,263,217 Total central proc. 106,012,558 Total SKA1,197,612,004 Costs for ‘this’ SKA Costs not Included: Development work Non-recoverable expenses Civil works Power installation Operational Costs Project Management Collectors 250 x 57m dia AA-hi 250x220m dia AA-lo 1200 x 15m dishes Wideband SPFeeds ~€1.2 Bn

SA Bursary Conference December 2009 SKA Design AA-hi Arrays (not inc. station processing) Infrastructure: Cover membrane Steels for Antenna Support Structure Cable Support Poles Velcro Cable Ties Foundations: building poles Civil Engineering Cooling Power Supplies Racking Trenches Infrastructure Build – 3 man years Bunkers Analogue Data Transport: Connection to PCBs = no. of cables Preparation of cables Cable - total length reqd per station Male plugs PCB Outlet plugs (i.e. PCB inputs to first processor) Install cables in field ~€1.5M each array, NPV ~€11 each element, 2011

SA Bursary Conference December 2009 SKA Design Summary

SA Bursary Conference December 2009 SKA Design. SA Bursary Conference December 2009 SKA Design Designing an optimal SKA around AAs at low frequencies.

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SA Bursary Conference December 2009 SKA Design. SA Bursary Conference December 2009 SKA Design Designing an optimal SKA around AAs at low frequencies.

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Presentation on theme: "SA Bursary Conference December 2009 SKA Design. SA Bursary Conference December 2009 SKA Design Designing an optimal SKA around AAs at low frequencies."— Presentation transcript:

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