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
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