technical foundations & enabling technologies – ds4

Technical Foundations &Technical Foundations &Enabling Technologies – Enabling Technologies – DS4DS4

Andrew Faulkner

April 22, 2023 SKADS Workshop 2006 Andrew Faulkner 2

Remit:Remit:

Technical foundations and

Enabling Technologies

The Demonstrator is:

2-PAD2-PAD


OverallOverall

• 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......


DS4 work scheduleDS4 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 finalise2-PAD designnote: individual subsystem work will continue

2008 Build 2-PAD

2009-1H Test 2-PAD and write reportReport on advances in subsystem research


RisksRisks

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


We need information from Site surveys

BitsBits

• 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

CANNOTCANNOT design for a European environment!!

First cut suggests that 4-bits is OK...(phew!)


2-PAD System2-PAD System

• Consider Station level AA with 2-PAD2-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 modelBuilding first model

• Focus on the bottlenecks– Possibility/availability of components

– CostCost


Possible Station - Side viewPossible Station - Side view


Desert

Station Proc. Local P.

FOV processing+ ¼ tile processing10m x 5m

FOV processing+ ¼ tile processing10m x 5m x 2.5m

Cooling systemUsing heat transfer ground

Optical fibredigital links

Tile processingfor ¼ of array5m x 5m x 2.5m

Array supportsproviding ~1.6m headroom

Inflation pumpEntrance

Element array50m x 50m

Short range analogue links from elements to local processing

Array physical support grid

Inflatable Ray dome

Possible Station - Side viewPossible Station - Side view

To scale


LocalProc.

LocalProc.

StationProcessing

LocalProc.

Matrix of supports~2m spacing (625)

Inflatable Ray dome

Entrance

Inflationpump

Element array50m x 50m

Tile processingfor ¼ of array5m x 5m

Optical fibredigital links

Wide area fibre link to Correlator

FOV processing+ ¼ tile processing10m x 5m

Short range analogue linksfrom elementsto local proc(only ¼ shown)

StationStationLayoutLayout(looking up)(looking up)


Tile Receiving elementsTile Receiving elements

LNA

Antenna

Filter+

DifferentialLine driver

Vert. Pol. Horiz. Pol.

Low cost screened twisted pair 20m max

Processing centre

+veReg Reg

IndividualPCB


‘‘Tile’ configurationTile’ configuration element receiver

=

Analogue twisted pair to Processing Centre

0 1 2 3 4 5 6 7 12 13 14 15 01234567

12131415

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

……

…

………………

…

……

… … … … … … … … …… … …


Overall StationOverall Station

Bunkers

…..

…..

..

..

..

16 x 16 array of Tiles ~2300 m2

256 Tile processors

FOV1

256 x 256 1GHz Analog links

FOV2

FOV8

…..

8 (say) FOV

processors

TP1TP2TP3

TP17TP18TP19

TP254TP255TP256

…..

.

256 x 85-10Gb Optical

fibres

1GHz signalsFrom each element

600MHz BWFOVs; 8 per tile

32 off40Gb Optical

fibres per FOV polarisation

To Correlator

256 beams of 600MHz BW

per FOV

Assumes 4-bit samples


Final Thoughts....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 AAAA appears:

possible, practical and cost effective

technical foundations & enabling technologies – ds4

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