AA-mid demonstrator

Dion Kant

AAVP 2010

8 – 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^2

Number of stations 10 to 15

Polarisation Dual polarisation

Frequency range 400 – 1450 MHz

Architecture Based on EMBRACE

T_sys 50K Target

Dynamic range @ ADC 42 dB

Instantaneous bandwidth ~250 MHz

Number of independent FoVs 2

HPBW (FoV) 16 degrees @ 1 GHz

Station 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

AA-mid 13 - GWK, 2010/12/10AAVP 2010

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

AA-mid 15 - GWK, 2010/12/10AAVP 2010 15

• 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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AA-mid 19 - GWK, 2010/12/10AAVP 2010

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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