AA-mid demonstrator

Dion Kant

AAVP 20108 – 10 December 2010, Cambridge, UK.

AA-mid 2 - GWK, 2010/12/10AAVP 2010

Outline

• Project target• Description of Work• Project partnerships• Current activities• Evaluation results• Conclusion

AA-mid 3 - GWK, 2010/12/10AAVP 2010

AA-mid (draft) key requirements

Physical collecting area ~2000 m^2Number of stations 10 to 15Polarisation Dual polarisationFrequency range 400 – 1450 MHzArchitecture Based on EMBRACET_sys 50K TargetDynamic range @ ADC 42 dBInstantaneous bandwidth ~250 MHzNumber of independent FoVs 2HPBW (FoV) 16 degrees @ 1 GHzStation output bandwidth 500 MHz

Requirements may still be adapted

AA-mid 4 - GWK, 2010/12/10AAVP 2010

AA-mid time line, phases and

• Full project (~2000 m^2 AA) not funded today• AAVS1 = first phase • Funding for design phase within AAVS1

– 2010 to 2013– Delivers design + small number of front end proto types– Use EMBRACE evaluation as input for design– Use EMBRACE platform as test-bed for new tile developments– New design based on EMBRACE

• Site selection will be decided on later• First testing will be performed at current EMBRACE stations• Second stage testing: Use Portugal site (SKA like environment)• Second phase (AAVS2) (beyond 2013) full roll-out AA-mid

demonstrator

AA-mid 5 - GWK, 2010/12/10AAVP 2010

Design approach

• Base new design on EMBRACE architecture and other demonstrators• Incremental approach

– Level 1 topics (should)– Level 2 topics (may)

• Main enhancements are (level 1 topics):– Introduce dual polarisation signal processing– Reduce power consumption per signal path– Improve tile control system– Reduce system noise– Second generation beam former chip (4-bit phase control)– Improve mechanical design, this includes housing & radome– Improve design for manufacturability

AA-mid 6 - GWK, 2010/12/10AAVP 2010

Design approach level 2 topics

• Investigate LNA above ground plane (integrated on feed board). Main goal is to be able to use FR4 for feed board (element cost reduction)

• Investigate balanced LNA approach• Improve station processing bandwidth

– Input bandwidth (250 MHz per channel)– Output bandwidth >2x250 MHz– As a fall back current EMBRACE

processing hardware will be used• Investigate non-continues

Unit/substation approach;• Obtain better EM model of tile to predict radiation pattern

including polarisation behavior. • ….

AA-mid 7 - GWK, 2010/12/10AAVP 2010 7

• XX “tiles” in a substation.• Every substation slightly tilted.• Substation closed by EPS wall en top.• Passive cooling by ground connection through poles.

• SKA station formed by multiple substations.• Walkable spaces between substations.• 56m diameter

288.000 antenna elements

Non-continues substations

AA-mid 8 - GWK, 2010/12/10AAVP 2010

Design approach level 2 topics

Topics to be solved :• Need software development partnership• Need correlator suitable for 15x2x1GS/s inputs• …

Can survive with current EMBRACE system in first phase of the project

AA-mid 9 - GWK, 2010/12/10AAVP 2010

Project partnerships

• Established members:– OPAR, France: Part of system design, beam former chip design,

EMBRACE evaluation;– ASTRON, the Netherlands: Part of system design, focus on level 1 front-

end topics, industrialisation and EMBRACE evaluation– …

• Members (becoming established):– Italy, INAF: Possible topics: Receiver, LO system, …– UK Several Institutes: Antenna design alternatives including electronic

integration and testing, Digital processing, …– Germany, MPIfR: Signal distribution and multiplexing, digital processing;– Portugal, Preparation for Portugal station roll out and site development– France, AD converter including poly phase filter bank integration– …

AA-mid 10 - GWK, 2010/12/10AAVP 2010

Current Activities and Progress

• First AAmid proto type tile underway

Octa boardsConnection boards

Center boardAluminum ground plane

AA-mid 11 - GWK, 2010/12/10AAVP 2010

Current Activities and Progress

• First AAmid proto type tile underway

Bottom view Octa concept

AA-mid 12 - GWK, 2010/12/10AAVP 2010

AAmid Octa Concept; 3D bottom view

Current Activities and Progress

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Improved element mechanics

SKA Station Design

Multiple vivaldi antennas in one sheet

LNA close to pick-up point

Plastic support to keep tops in place

AA-mid 14 - GWK, 2010/12/10AAVP 2010

Aluminum Large Plates to decrease assembly time

SKA Station Design

Metal-Metal joining by clinching

Also expandable (connectable) in other

direction

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• XX “tiles” in a substation.• Every substation slightly tilted.• Substation closed by EPS wall en top.• Passive cooling by ground connection through poles.

• SKA station formed by multiple substations.• Walkable spaces between substations.• 56m diameter

288.000 antenna elements

EM analysis of non-continues substations

AA-mid 16 - GWK, 2010/12/10AAVP 2010

EM analysis of non-continues substations

Vacuum formed “tile” bottom for

six modules(approx. 1.5 x 2m)

Placement in field by forklift or crane,

like LOFAR HBA.

AA-mid 17 - GWK, 2010/12/10AAVP 2010

Small tile: Simulate and measure

AA-mid 18 - GWK, 2010/12/10AAVP 2010

Good resemblance model and measurements

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Good resemblance model and measurements

Measured and simulated phases

AA-mid 20 - GWK, 2010/12/10AAVP 2010

Current Activities and Progress

• EMBRACE Evaluation and test-bed development

AA-mid 21 - GWK, 2010/12/10AAVP 2010

Status Nançay Station

• ~ 62 m2 area 56 Tiles• 4032 Vivaldi elements (single linear polarisation)• Currently 48 tiles cabled up end-to-end• Grouped into tilesets of 4 tiles• 64 tiles to be installed by end 2010• Ultimately, 80 tiles in early 2011

Current Activities and Progress

AA-mid 22 - GWK, 2010/12/10AAVP 2010

Status Westerbork Station

• 64 Tiles, (~70 m^2)• 25 Tiles online in a 3x3 and 4x4 array configuration• Ultimately 144 Tiles (160 m^2) in 2011

Current Activities and Progress

AA-mid 23 - GWK, 2010/12/10AAVP 2010

Digital beam former details

AA-mid 24 - GWK, 2010/12/10AAVP 2010

Modified architecture to more generic one

• Full data rate can be exploited:• 2x62 Ebeamlets per CDO output; e.g.

two beams of 12 MHz each• Digital beam former software less

complex (can use Matrix formalism now)• Increased update rate digital beam

weights

AA-mid 25 - GWK, 2010/12/10AAVP 2010

EMBRACE station experiment objectives and results• Detection of GPS satellite signals• Scanned Beam Pattern on Afristar• Redundant base line experiments on Afristar• Solar Fringes and system noise verification• Fringes of Cas A and Cygnus• RECENT RESULT: Detection of pulsar

Current Activities and Progress

• Simultaneous detection of two pulsars within one FoV• Simultaneous detection of two widely separated pulsars

using independent FoVs• Detection of HI• Simultaneous detection of HI and pulsars• Beam swapping with beams on Cas A and Cygnus• Correlate with WSRT dish

• RECENT RESULT: Detection of pulsar

Plan

AA-mid 26 - GWK, 2010/12/10AAVP 2010

Drift scan of GPS satellite

• Strong carrier at 1227MHz• Subband statistics• Pointing offset between

tilesets

AA-mid 27 - GWK, 2010/12/10AAVP 2010

Early highlights: solar fringes

Interferometric measurement with 10 tiles two E-W ULAs frequency: 1179 MHz integration: 10 s bandwidth: 195 kHz

Initial performance est. A/T = 4.7·10-3 (to sun) Tsys = 103 – 117 K (to zenith)

AA-mid 28 - GWK, 2010/12/10AAVP 2010

Early highlights: instrument quality

• Redundant baselines produce redundant visibilities

Scanned Tile Beam pattern measured on Afristar satellite

Model Measurement

AA-mid 30 - GWK, 2010/12/10AAVP 2010

Fringes of Cas A!

• Experimental settings• 3x3 array• 1254 MHz• 30 s integration• 195 kHz bandwidth

• Initial conclusions• Confirms A/T• Correlation offsets

AA-mid 31 - GWK, 2010/12/10AAVP 2010

Pulsar detection Setup details

AA-mid 32 - GWK, 2010/12/10AAVP 2010

EMBRACE first pulsar result

AA-mid 33 - GWK, 2010/12/10AAVP 2010

Conclusion

• AA-mid is ramping up• EMBRACE Pulsar Detection demonstrates first L-

band AA detection ever! It demonstrates:• Complete data path and processing is under control• Hierarchical beam forming is working

• and much more to come

Thank you