Technologies for Radio Astronomy

Graeme Carrad | Assistant Director - Engineering

Mark Bowen | Group Leader – Front End Technologies

JULY 2012

CSIRO ASTRONOMY AND SPACE SCIENCE

OutlineTechnologies for Radio Astronomy

•CABB •ATCA C/X Upgrade•FAST

Parkes – Future Receiver Systems

Technologies | Graeme Carrad| Page 2

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.

Compact Array Broadband Backend

Technologies | Graeme Carrad| Page 3

ATCA C/X Upgrade

Parkes receiver options| Graeme Carrad| Page 4

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.

ATCA C/X Upgrade4.0 – 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

Parkes receiver options| Graeme Carrad| Page 6

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 Receivers

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?

What are we considering?First stage in developing a longer term plan

Parkes receiver options| Graeme Carrad| Page 8

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 would a PAF provide?

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.

What do we know?

Parkes receiver options| Graeme Carrad| | Page 10

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?)

What do we know?

Parkes receiver options| Graeme Carrad| | Page 11

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.

What do we know?

Parkes receiver options| Graeme Carrad| | Page 12

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.

Approaches

Parkes receiver options| Graeme Carrad| | Page 14

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.

Considerations

Parkes receiver options| Graeme Carrad| | Page 15

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?

Timelines

Parkes receiver options| Graeme Carrad| | Page 16

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.

PrioritiesParkes

Parkes receiver options| Graeme Carrad| | Page 17

Compact Array

Future ATUC meeting - The case for going to 12.2 GHz on the ATCA.

Thank youCSIRO Astronomy and Space ScienceGraeme CarradAssistant Director - Engineeringt +61 2 9372 4305e Graeme.Carrad@csiro.auw www.csiro.au/lorem

CSIRO ASTRONOMY AND SPACE SCIENCE

CSIRO Astronomy and Space ScienceMark BowenGroup Leader – Front End Technologiest +61 2 9372 4356e Mark.Bowen@csiro.auw www.csiro.au/lorem