Technologies for Radio Astronomy
Graeme Carrad | Assistant Director - Engineering
Mark Bowen | Group Leader – Front End Technologies
JULY 2012
CSIRO ASTRONOMY AND SPACE SCIENCE
Outline
Technologies for Radio Astronomy
• CABB
• ATCA C/X Upgrade
• FAST
Parkes – Future Receiver Systems
Technologies | Graeme Carrad| Page 2
Compact Array Broadband Backend
Status
• 64MHz zoom mode with all 16 zooms available has an estimated delivery
date this winter season.
• Late but can only apologise.
• The complexity demands more experienced resources and they are not
available. It is estimated at 90% complete with the remaining work being to
output the data in a suitable format to cope with the data rate at 64 times the
1 MHz rate. Not all the data can come out at once.
• Tim Bateman, Bob Sault and Warwick Wilson tackling, successfully, a long
list of operational issues highlighted by Jamie Stevens and Robin Wark.
• Last ATUC meeting it was asked, do we stop zoom development after
64
MHz delivery and fix CABB’s bugs first? – The feeling is that much will have
been accomplished in bug fixes.
Technologies | Graeme Carrad| Page 3
ATCA C/X Upgrade
Status
• Australian Astronomy Ltd. funded program - upgrade
funding continues until June 2013.
• Prototype receiver installed on ATCA during Nov 2011.
• Development of a production LNA is complete and the
manufacture of LNA hardware is underway.
• The manufacture of hardware and components for the
production receivers is well underway.
• The first two receivers (production) are currently in the
CASS Marsfield laboratories undergoing modification.
• Two production receivers will be installed on the
ATCA during Aug – Sep 2012.
Parkes receiver options| Graeme Carrad| Page 4
ATCA C/X Upgrade
4.0 – 12.25GHz Feed Prototype
• Existing C/X feed horn does not work above 10.8GHz.
• Feed investigations carried out by CSIRO ICT Centre and
BAE Systems.
• Consultation with user community identified limited
interest in extending operation from 10.8GHz – 12.0GHz.
• A prototype 4.0 – 12.25GHz feed horn will be delivered
by BAE Systems.
• The feed will be tested on the ICT Centre
antenna range then installed on the ATCA for
evaluation.
• An estimate of the cost to outfit the ATCA
including new feeds and CABB signal path
hardware modifications will be made.
FAST Multi-beam Receiver - Feasibility Study
Background
• 19 beams at 1.05GHz – 1.45GHz.
• CSIRO ICT Centre designing feed and OMT, CASS
studying LNA and cryostat.
• JBCA developing alternative designs.
Status
• ICTC feed electromagnetic design complete.
• CASS LNA and cryostat design underway.
Parkes receiver options| Graeme Carrad| Page 6
Parkes Receivers
What are we considering?
First stage in developing a longer term plan
Wideband Receiver
 700 MHz to 4 GHz
 4 – 16GHz (18GHz?) (20GHz?)(24GHz?)
PAF
 Frequency coverage comparable to ASKAP PAF?
20 - 25GHz Multibeam Receiver
 Does this development make the most from the feasibility studies?
 Should we build another multibeam receiver?
Parkes receiver options| Graeme Carrad| Page 8
What would a PAF provide?
 ASKAP MkII system is already achieving rather competitive
Tsys/η ≈ 55 K on 12 m, likely between about 800 – 1600 MHz.
 PAFs provide much better spectral baseline performance than
SPFs.
 New science possibilities with 36 beams:
– Pulsar surveys
– Deep HI for “Intensity Mapping” and “HI Cosmic Web”
What do we know?
Wideband Receivers
 MPIfR are developing a 600 MHz - 3 GHz receiver with uncooled
feed/OMT. Target of Tsys ≤ 50K
 Our own investigations indicate the wideband elements are non
trivial/difficult to design despite knowledge of the MPIfR program.
 Cooling the feed/OMT is desirable but presents a challenge.
 The wide bandwidth is likely to require a compromise - lesser
performance than current receivers over some or all of the band.
 This development may complement plans for future receiver
rationalisation.
 At this stage we do not know enough to advise on likely
performance.
Parkes receiver options| Graeme Carrad| | Page 10
What do we know?
PAF
 Experience in modelling, fabricating and the performance (ASKAP).
 BETA PAF exists – Mk. 1.
 ADE PAF is under development but the initial results (5x4) look
promising – Mk. 2.
 Current BETA PAF on Parkes is likely to be an ‘experiment’. This
might be a quick way to explore PAFs on a large dish but will carry
an operational overhead. Additional resources required from
proponents.
 CASS is more likely to lead a program for a PAF with the
performance of the current 5x4 (Full Bandwidth).
 Modularity is necessary for future upgrades. (Cryo PAF?)
 External support for a Parkes PAF has been mooted. (SIEF?)
Parkes receiver options| Graeme Carrad| | Page 11
What do we know?
20 – 25 GHz Multibeam Receiver
 We have the experience in this frequency range.
 MMIC fabrication is almost certainly required together with a
significant conversion and frequency conversion scheme.
 Likely high cost and longer term program to deliver.
 The Parkes dish performance is poorer at these frequencies
compared with the lower frequencies.
 The majority of observing at Parkes (~70%) is done at lower
frequencies.
Parkes receiver options| Graeme Carrad| | Page 12
Approaches
Wideband Receivers
 Conduct a feasibilty study to determine the design, performance and
compromises as well as addressing some of the challenges in cooling.
 This study is likely to take 6 months (best estimate).
 Backend considerations aligned with Parkes needs.
 Stay in touch with MPIfR progress.
 A 4GHz ‘up’ proof of concept to start off would be smaller and physically less
demanding, provide experience and give Parkes enhanced capability.
 It may be more appropriate to start development at the higher frequency as
one step in the path to the 700MHz – 4GHz receiver.
 Starting with a 600MHz to 4GHz receiver addresses the majority of the
observing but if the performance falls short there is knowledge gained but no
suitable receiver to replace existing ones.
 A successful implementation of a 700MHz – 4GHz also aligns with the strategy
of reducing receiver changes.
Parkes receiver options| Graeme Carrad| | Page 13
Approaches
PAF
 Conduct a feasibility study to determine scope of work required to fit a PAF to
Parkes.
 How good does the PAF need to be?
 Does it need to be a replacement for the centre beam of the L band multibeam?
 If that can’t be achieved with current designs then that implies more
development. This will set the timeline for implementation.
 Can a new chequerboard and amplifiers coming from ADE developments be
adapted for a BETA PAF?
 Upgrade path for BETA and ADE PAF systems.
 Have a design team start exploring the incorporation of BETA and ADE PAF
structures into Parkes focus cabin – mechanical and heat load considerations.
 Backend considerations aligned with Parkes needs.
Parkes receiver options| Graeme Carrad| | Page 14
Considerations
Calibration
 A parallel program to ensure a calibration scheme is developed along with both
wideband receiver and PAF.
 Single dish as opposed to array for PAF.
RFI
 Future developments in communications threaten low frequency band
integrity.
 Do we program mitigation in, or abandon specific frequency bands?
 The backend complexity/cost might be defined by the need cross correlation or
other mitigation techniques.
Resources
 There is likely to be sufficient effort available to study the feasibility of two
developments in parallel i.e Wideband receivers and PAF.
Parkes receiver options| Graeme Carrad| | Page 15
Timelines
 Nice to have studies done for the next ATUC meeting (Nov) but that seems too
soon. We will report on progress of the studies then.
 The June 2013 meeting might be too far away to seek advice on the outcomes
of the studies so an out of session gathering might be considered?
Parkes receiver options| Graeme Carrad| | Page 16
Priorities
Parkes
 Are there other options?
 Is the high frequency multibeam the lower priority of the three
considerations?
 We are likely to investigate both, but if there was a preference for
investigating wideband receiver or PAF which would it be?
 We feel our wideband approach is less risky than the ‘all eggs in
one basket’ consideration of the lower frequency receiver only.
Compact Array
 Future ATUC meeting - The case for going to 12.2 GHz on the
ATCA.
Parkes receiver options| Graeme Carrad| | Page 17
Thank you
CSIRO Astronomy and Space Science
Graeme Carrad
Assistant Director - Engineering
t +61 2 9372 4305
e Graeme.Carrad@csiro.au
w www.csiro.au/lorem
CSIRO ASTRONOMY AND SPACE SCIENCE
CSIRO Astronomy and Space Science
Mark Bowen
Group Leader – Front End Technologies
t +61 2 9372 4356
e Mark.Bowen@csiro.au
w www.csiro.au/lorem