1. Technical Foundations & Enabling Technologies – DS4
Andrew Faulkner

2. Technical foundations Enabling Technologies
Remit:
Technical foundations
and
Enabling Technologies
The Demonstrator is:
2-PAD
4 December 2018
SKADS Workshop 2006

3. Overall There are 3 more years......
DS4 very broad range with many institutions involved
Schedule is disrupted – particularly in UK – due to funding delays (funds now awarded)
We will deliver by June 2009
There are 3 more years......
4 December 2018
SKADS Workshop 2006

4. DS4 work schedule 2006 Investigate and consider any possible approach.
Blue Sky etc...
2007-Q1 Select 2 or 3 of the most likely approaches
2007 Prototyping and developing phase.
Build models, bring together systems
2008-Q1 Select 2-PAD components and finalise
2-PAD design
note: individual subsystem work will continue
2008 Build 2-PAD
2009-1H Test 2-PAD and write report
Report on advances in subsystem research
4 December 2018
SKADS Workshop 2006

5. Risks Low Risk: the components exist, but can be improved....
Antenna array, needs performance and cost and ease improvement
LNA, the system noise and the cost need to be improved
Processing, currently far to little capacity, but will work at some limited bandwidth
High Risk: does not exist...
Low power, low cost high speed ADC
Cheap enough analog links – must be <€5 each
RFI mitigation - unproven
4 December 2018
SKADS Workshop 2006

6. We need information from Site surveys
Bits
Digitisation is not to do with instrument dynamic range!
It is to do with the RFI environment.
To make a practical all-digital aperture array must use minimal digitisation e.g. 4-bits
CANNOT design for a European environment!!
We need information from Site surveys
First cut suggests that 4-bits is OK...(phew!)
4 December 2018
SKADS Workshop 2006

7. 2-PAD System Consider Station level AA with 2-PAD as a subsystem
Hence understand scaling and processing issues
Distances, cooling, power etc
Station wide construction requirements
Reliability analysis (system layout vital)
Important to have benchmark specification!
Building first model
Focus on the bottlenecks
Possibility/availability of components
Cost
4 December 2018
SKADS Workshop 2006

8. Possible Station - Side view
4 December 2018
SKADS Workshop 2006

9. Possible Station - Side view
Element array
50m x 50m
Inflatable
Ray dome
Short range analogue links from
elements to local processing
Array physical
support grid
To scale
Entrance
Inflation pump
Station Proc.
Local P.
Desert
FOV processing
+ ¼ tile processing
10m x 5m x 2.5m
FOV processing
+ ¼ tile processing
10m x 5m
Array supports
providing ~1.6m
headroom
Cooling system
Using heat transfer
ground
Optical fibre
digital links
Tile processing
for ¼ of array
5m x 5m x 2.5m
4 December 2018
SKADS Workshop 2006

10. Station Layout (looking up) 4 December 2018 SKADS Workshop 2006
Short range
analogue links
from elements
to local proc
(only ¼ shown)
Matrix of supports
~2m spacing (625)
Local
Proc.
Local
Proc.
Inflatable
Ray dome
Station
Layout
(looking up)
Element array
50m x 50m
Optical fibre
digital links
Entrance
Station
Processing
Local
Proc.
Wide area
fibre link to
Correlator
Tile processing
for ¼ of array
5m x 5m
Inflation
pump
FOV processing
+ ¼ tile processing
10m x 5m
4 December 2018
SKADS Workshop 2006

11. Tile Receiving elements
Vert. Pol.
Horiz. Pol.
Antenna
LNA
Filter +
Differential
Line driver
+ve
Reg
Reg
Individual
PCB
Processing centre
Low cost screened twisted pair
20m max
4 December 2018
SKADS Workshop 2006

12. ‘Tile’ configuration … … … … … … … … … … … … … … … … … … … … … … … … 1 2 3 4 5 6 7 12 13 14 15 …
element
receiver = … …
Notes:
16 elements / side
Groups of 16 Rx
in a cluster (4x4)
Overall size:
3.0m square
9.0m2
512 links / tile
(2x16x16) … … … … … … … … … … … … … … … … … … … … …
4x4 receiver units
Analogue twisted pair to Processing Centre
4 December 2018
SKADS Workshop 2006

13. Overall Station } .. .. To Correlator ….. ….. ….. ….. .. . Bunkers
Assumes 4-bit samples
256 Tile
processors
8 (say) FOV
processors
1GHz signals
From each element
600MHz BW
FOVs; 8 per tile
256 beams
of 600MHz BW
per FOV
16 x 16 array
of Tiles ~2300 m2
Bunkers
TP1
FOV1
TP2 .. }
TP3 .
TP17
FOV2 ..
TP18
TP19
To Correlator
…..
…..
…..
…..
FOV8 ..
TP254
TP255
256 x 8
5-10Gb Optical
fibres
32 off
40Gb Optical
fibres per
FOV polarisation
TP256
256 x 256 1GHz Analog links
4 December 2018
SKADS Workshop 2006

14. possible, practical and cost effective
Final Thoughts....
Cost dominated by array and analogue links
Total power requirements vital
Power and cost of ADC an issue
Communications for the internal data streams
Continue system design:
Frequency dependant aperture
Calibration approaches
Independent many small beams over whole scan angle
Flexibility on beams/bandwidth/sampling for Tx to correlator
On SKA timescales: a digital AA appears:
possible, practical and cost effective
4 December 2018
SKADS Workshop 2006