Äîêóìåíò âçÿò èç êýøà ïîèñêîâîé ìàøèíû. Àäðåñ îðèãèíàëüíîãî äîêóìåíòà : http://www.atnf.csiro.au/projects/askap/techdocs/berkeley_overview.pdf Äàòà èçìåíåíèÿ: Fri Jul 20 05:44:22 2001 Äàòà èíäåêñèðîâàíèÿ: Sat Sep 6 16:51:10 2008 Êîäèðîâêà: Ïîèñêîâûå ñëîâà: http www.astronomy.ru forum index.php topic 4644.0.html

Australian SKA ­ Progress & Directions
Peter Hall
Berkeley, July 2001

http://www.atnf.csiro.au/SKA


Australian SKA ­ Year At A Glance
n

Formation of Australian SKA Consortium
­ Executive Committee, Science & Engineering Working Groups now functional ­ First symposium held Feb. 2001

n

Major National Research Facilities (MNRF) bid
­ Submitted May 2001; outcome known August 2001 ­ Contained proposals for 2 major SKA demonstrators

n n n n

Technical Work
­ Significant results in antenna and interference mitigation projects

Site Survey
­ First field work completed in Western Australia

Collaborations
­ Industry and international SKA joint work increasing

Outreach
­ Professional and community



SKA Outreach
n

Professional
­ ­ ­ ­ Institution of Engineers national congress `Engineering World' article ITEE Society mailout Spectrum management & community issues
» Introducing Radio Quiet Zone concept

n

Government
­ ­ ­ ­ Federal parliamentary briefing South Australian Govt. briefing Continuing Western Australian interaction Emerging New South Wales interest

n

General
­ Radio, TV, print material
» Site tests » Prototype Luneburg Lens

­ Local & indigenous community contact


Australian SKA: Some Pictorial Philosophy

Widely separated multi -beaming Wide field-of-view Active interference mitigation Broadband


CSIRO SKA Program ­ Highlights
n

Antennas
­ Luneburg Lens EM design & analysis ­ encouraging first results ­ Russian prototype Luneburg Lens ­ Materials science: Artificial dielectrics & manufacturing » Powders and wires ­ Phased array collaboration (ASTRON, industry....)

n

Site tests & data visualization
­ Initial Western Australia field work ­ Characterize sites AND contribute to international site selection process

n

Interference mitigation
­ Strengths in post-correlation IM ­ Extending to simultaneous multiple satellite sources (IRIDIUM, GLONASS) ­ ATCA operational IM goals

N

Þ Poster N & coffee


Luneburg Lenses for SKA


11

Konkur Luneburg Lens
· Obtained with PRAO collaboration · Two initial uses: - Verify EM design & analysis - Int Mit reference antenna · Currently under test by CSIRO
Diameter Operating frequency range Gain (12 GHz) Aperture efficiency Sidelobe level (standard horn feed) Focal distance Mass 2r = 0.9 m To 12 GHz 39 ± 0.5 dB > 50% < -17 dB 1.5r 90 kg -50 to +50 °C

(Patented construction process)
Operating temperature range


Konkur Lens: First Results
Amplitude (Ref centre meridian plane)

12 GHz Tests; TV Feed

Far-field Beam

2D Beam (Co-polar)

Directivity ~ 39.3 dBi Raw aperture eff ~ 67% - with 0.5 dB dielectric loss ~ 57%


Industry Link: Advanced Nano Technologies
· Collaboration between Advanced Powder Technology (Aust) and Samsung Corning (Korea) · Make particles smaller than thickness of DNA string · Unique chemical, mechanical, optical, magnetic properties · Great potential in artificial dielectrics


Industry Link: CEA Technologies
· Canberra based ·150 employees, $20M turnover ·Modular S and X-band radars sold internationally ·Interested in becoming involved in SKA prototyping


25

Practical Interference Mitigation

Before
ATCA, 1500 MHz, Terrestrial Data Link Interference

After

Post-Correlation Interference Mitigation


37

Site Tests ­ First WA RFI Survey
· CSIRO & WA Govt -Private contractor · 27 March ­ 17 April 2001 ·"First look" study -Representative RFI at one site -Highlight practical challenges -Compare with spectrum database · Analysis continuing ­ reports this week


5

Australian SKA Demonstrators
n n

Explore new territory
­ Concentrators, signal processing....

Money amounts are small ( ~ $US 10M)
­ Careful selection of concepts
» Best short-term astronomy best SKA demo

n

Cover "big" and "smart"
­ Address hard radio science issues AND ­ Focus on scaling and cost issues relevant to SKA

n

Integrate with existing telescopes
­ Extends host's capabilities ­ Allows detailed assessment of concept

n

Contribute to 2005 concept assessment


MNRF Bid ­ The Money Trail
MNRF Bid ($US29M)

Gemini ($18M)

SKA ($11M)

Figures Include 50% Matching Funds

Sydney U. ($0.9M)

CSIRO ($8M)

Swinburne U. ($1.25M)

Molonglo Demonstrator

ATCA Demonstrator, SKA Key Technologies

SuperComputer Simulation, Visualization


5, 10, 21

SKA Demonstrators: What We Propose
n

AT Compact Array demonstrator ($US 6M)
­ New 2 GHz F/X correlator
» Main short-term "astronomical" deliverable » Complements recent mm- wave ATCA upgrade

­ 2 x mini SKA stations
» Final number and form TBD · Lenses or phased arrays prime contenders



"Smart"

­ 4 m Luneburg Lens » Multi-beaming IM reference antenna using AD
n

Molonglo cylindrical reflector demonstrator ($US 0.9M)
­ Multibeaming and advanced DSP

"Big"

n

SKA enabling technology ($US 1.5M)

­ Active focal plane/surface arrays, highly-integrated receivers n System simulations & software correlators ($US 1.25M)


5

ATCA Demonstrator


ATCA Demonstrator ­ Design Decisions
n n

Form of station
­ Concentrator (lens) vs phased array

Number & layout of stations
­ Balance ATCA gains vs breadth of SKA demonstrator
» Calibration issues crucial (min size, ability to adequately test homogeneous elements....) · Potentially powerful `holography' modes

n

Nature of interconnection
­ Fibre interconnect ­ analog or digital? ­ DWDM demonstrator

n

RF issues
­ Should demonstrate highly integrated receiving systems ­ New photonic sampling scheme


22

Photonic PAM System
Antenna K

A Sub-Array Incorporating Impulse Sampling and Photonic A/D Conversion

Antenna 2 Antenna 1 BASE STATION
High repetition rate, low jitter pulse source locked to station reference clock
Multiwavelength Optical Pulse Source
1 1

Receiving Element

To K Antennas

2 2



3 3

... .

N

1xK

Electro-optic Modulator

Detectors and LPFs
DSP A/D

Short optical pulses sample RF at antenna

N

From K Antennas

..



3 3

Downconversion Fringe Rotation Correlation etc

A/D A/D A/D

2 2

WavelengthDivision Demultiplexer



N

....



3 3



2 2



1 1

1 1

-coded samples separated by filter and digitised in parallel


10, 21

Molonglo Demonstrator
n n

18,000 sq m cylindrical paraboloid Currently:
­ 843 MHz operation ­ Analog beamforming

n

Proposed:
­ ­ ­ ­ 300 -1420 MHz coverage Multi-beam line feeds Digital beam formation Versatile FX correlator

n

New observing modes, new science


Australian SKA Directions
n n n

Demonstrator design & construction
­ Selection of demonstrator concepts by Dec 2002

More site studies work
­ Extension to other states

More R&D in additional key technical areas
­ Phased array concept ­ Highly-integrated RF systems ­ Photonics
» Transport, connectivity, RFI filtering » High speed analog ­ digital conversion

­ Configurations and system simulation...need to un-stall
n n

Engagement of wider astronomy community
­ e.g. making the Gemini link real

Expansion of industry and international SKA links
­ Artificial dielectrics Þ prototype Luneburg Lenses ­ Phased array prototypes, integrated receivers, signal processing...