2Polarisations All Digital

1
2-Polarisations All Digital
2-Polarisations All Digital
2-PAD

• Dr Georgina Harris / Prof Tony Brown
• SKADS System Design and Team Leader, University
  of Manchester
• Thanks to the 2-PAD Team
• Manchester Chris Shenton, Tim Ikin, Aziz
  AhmedSaid, Richard Whitaker,
• Tony Brown, Dan Kettle, Mina Panahi
• Oxford Mike Jones, Kris Zarb Adami, Sasha
  Shidewy
• Cambridge Andrew Faulkner
• Astron Jan Geralt bij de Vaate, Raymond van
  den Brink

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2-PAD Aims

• To produce a flexible platform upon which to test
  a variety of subsystems for the Aperture Array
  for the SKA
• Digital beamforming
• Prove it can be done
• Realistic technology projections for cost/ power
• Low self induced RFI
• Low cost interconnects are feasible
• Dual polarisation measurements
• Proof of calibration at tile level

3
2-PAD System Design
Bunker RFI Shield
Analogue Conditioning
64 dual channels
Ant. polarisation
4 off Beamformer. Processors
Processor
Total 128 inputs
Digital Pre- processor
ADC
PSU
Beamformer Processing
Beam combiner Processor
ve
Reg

.....
.....
.......
PCB
Output Beams
Analog Conditioning
.......
From other beamformer proc.
Digital Pre- processor
ADC
Analog Interconnect CAT7?
PSU
LNA
64 elements x2 polarisations
Control Processor
Time standard
Up to 20m
Line Tx/Rx
Buffers
Control
Signal Conditioning Rack
Processing Rack
Bunker
Outdoors
4
Antennas

• 2-PAD will use 3 sets of array antennas
• Each antenna tile will be 16 x 16 dual
  polarisation elements
• The central 8 x 8 elements will be active, i.e.
  the signals from these antennas will be amplified
  and processed
• The remaining antennas will be loaded elements,
  i.e. they are present only to reduce the edge
  effects on the central 8 x 8
• Each antenna type is due to be produced as a
  passive tile for RF testing
• After testing, the active antennas will be used
  for 2-PAD.

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Antennas

• FlowPAD antenna
• from our colleagues at Astron
• used as a reference design by which to benchmark
  our other antennas

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Antennas

• BECA
• (Bunny Ear Combline Antenna)
• Designed by the University of Manchester
• A development of a Vivaldi Structure

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Antennas

• ORA
• (Octagon Ring Antenna)
• Designed by the University of Manchester
• New Antenna Design see talk by David Zhang

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2-PAD LNA

• The LNA for each antenna must be impedance
  matched and designed to integrate mechanically
  with the antenna
• There are currently three teams working on LNAs
  in SKADS for 2-PAD
• A completely new single-ended LNA developed in
  Indium Phosphide in Manchester
• A differential LNA designed at ASTRON at 150W
  impedance for use with FlowPAD and BECA antennas
• A differential LNA made up from discrete
  components in Manchester at 150W for use with
  FlowPAD and BECA antennas
• It is likely that the discrete component LNA will
  be installed on 2-PAD initially, however, it will
  be possible for each LNA to undergo validation on
  the 2-PAD platform.

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Gain Chain Version 1
Gain 72dB
Designed constructed and characterised by Richard
Morrow
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2-PAD System Design
Bunker RFI Shield
Analog Conditioning
64 dual channels
Ant. polarisation
4 off Beamformer. Processors
Processor
Total 128 inputs
Digital Pre- processor
ADC
PSU
Beamformer Processing
Beam combiner Processor
ve
Reg

.....
.....
.......
PCB
Output Beams
Analog Conditioning
.......
From other beamformer proc.
Digital Pre- processor
ADC
Analog Twisted Pair
PSU
LNA

• Signal conditioning module
• Analogue signal conditioning on replaceable
  mezzanine board
• Off-the-shelf A/D initially
• FPGA for data conversion and initial signal
  processing

64 elements x2 polarisations
Control Processor
Time standard
Up to 20m
Line Tx/Rx
Buffers
Control
Signal Conditioning Rack
Processing Rack
mini-Bunker
Outdoors
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Receivers
Shielded Bunker
Analogue Conditioner And Sampling Rack
Processor Rack
Front-end Gain.
20Gb
Conditioning Module
Acquisition Processing
Processor Blade
Processor Blade
Processor Blade
Processor Blade
Acquisition Processing
Conditioning Module
Processor Blade
Processor Blade
Acquisition Processing
Conditioning Module
Processor Blade
Processor Blade
Acquisition Processing
Conditioning Module
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Signal conditioning
Midplane
Power Module
Clock Module
2-channel signal conditioning module
2-channel acquisition and processing module
2 x 10Gb Links
Signals from field
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Analogue Conditioning Board
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Analogue Conditioning Board
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DAQ Board
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DAQ Board
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2-PAD System Design
Bunker RFI Shield
Analog Conditioning
64 dual channels
Ant. polarisation
4 off Beamformer. Processors
Processor
Total 128 inputs
Digital Pre- processor
ADC
PSU
Beamformer Processing
Beam combiner Processor
ve
Reg

.....
.....
.......
PCB
Output Beams
Analog Conditioning
.......
From other beamformer proc.
Digital Pre- processor
ADC
Analog Twisted Pair
PSU
LNA
64 elements x2 polarisations

• Processing Subsystem
• 2-PAD Designed to enable the testing of different
  types of processing
• PrepSKA follow-on work to further investigate
  options

Control Processor
Time standard
Up to 20m
Line Tx/Rx
Buffers
Control
Signal Conditioning Rack
Processing Rack
mini-Bunker
Outdoors
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Initial Processing for 2-PAD

• Cyclops processor (IBM)
• Cyclops blades in high-bandwidth rack
• 80 GFlops/blade
• Up to 48 blades/rack
• SIMD Architecture
• 160 thread units per chip
• Further Options see Chris Shentons
  presentation

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Cyclops frame at Jodrell
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Cooling System

• We have a cooling system for 2-PAD which
  includes
• A closed-loop controlled water cooling system
  used to cool the processor chips to keep them
  running at their most efficient
• An air conditioning system used to cool the other
  electronics in the bunker
• The two systems work together to keep the
  electronics at the correct temperature and
  humidity without compromising the RFI shielding
  of the bunker
• This cooling system will make use of free
  uncooled air from outside the bunker whenever
  ambient temperatures permit.

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2-PAD System Design
Bunker RFI Shield
Analog Conditioning
64 dual channels
Ant. polarisation
4 off Beamformer. Processors
Processor
Total 128 inputs
Digital Pre- processor
ADC
PSU
Beamformer Processing
Beam combiner Processor
ve
Reg

.....
.....
.......
PCB
Output Beams
Analog Conditioning
.......
From other beamformer proc.
Digital Pre- processor
ADC
Analog Twisted Pair
PSU
LNA

• Bunker and Shielding
• RFI mitigation techniques
• Housing and cooling system
• Standard container structure

64 elements x2 polarisations
Control Processor
Time standard
Up to 20m
Line Tx/Rx
Buffers
Control
Signal Conditioning Rack
Processing Rack
mini-Bunker
Outdoors
22
Processing Bunker Design
The processing bunker will be manufactured to the
basic pattern of a standard transport container.

• Dual Function
• Provide RFI Shielding
• Permits the processing bunker to be filled with
  computers before it is shipped

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Bunker RFI shielding

• Connect via screened sockets
• Cables through tube
• Wrap foil along cable
• gt60dB suppression at 1GHz, so far

ARJ45 screened connectors
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Potential SKA Station Layout
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Software

• A highly optimised kernel and software library
  has been created for the Cyclops processor from
  scratch in Manchester
• A comprehensive MATLAB broadband beamforming
  model has been developed
• We have a vendor developed software simulator for
  the Cyclops processor and the first version
  single polarisation beamformer has been
  implemented (in the simulator environment). This
  is currently being validated against the MATLAB
  model (refer to presentation by Aziz AhmedSaid).

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2-PAD should be integrated and ready for test by
Q1 2009!