ASKAP Data Transmission and Signal Transport
The signal distribution and data interconnectivity systems for ASKAP include the data transport from the telescope site to a major network link.
As ASKAP can be configured as either an interferometer or single phased array dish (sum of 36 antennas), both phase coherent receiver and signal processing systems are required.
Atomic clocks and back-haul data transport systems used by ASKAP will also be made available for use by other arrays, experiments and facilities sharing the Murchison Radio-astronomy Observatory (MRO) site.
Antenna specific hardware and subsystems is being developed in the Sydney laboratories and tested at the phased array feed (PAF) testbed antenna at Parkes.
A paper detailing the architectural requirements for the ASKAP system and the role of cost effective photonics solutions for the transport of signals within each antenna, intra-array, and to the outside world, can be found here (pdf, conference paper pre-print).
Technical challenges
The transport of the astronomical data signals from the PAF to the analogue to digital convertor (ADC) systems and on to the digital beamformer is a key challenge for ASKAP and for SKA in the future. The hundreds of feed elements required in the PAF necessitate a large number of connections through rotating cable wraps at all three antenna axes.To synchronize the array, high quality local oscillator signals will be sent from a central master timebase, an ultra pure 16MHz carrier.
Connecting antennas to the central site digital signal processing (beamformer and correlator) will require Terabit per second data pipelines over distances of up to 8 km. The total output data rate per antenna will be approximately 2 Tbps and the total input rate to the digital beamformers will be a continuous 72Tbps. Commercial off-the-shelf 1Ge Ethernet will be networked to each antenna and around site for system monitoring and control.
A long-haul (400km) DWDM data transmission system with three intermediate repeater huts will also be needed for transport of visibility data from the remote array site (the MRO) to the Geraldton science centre (the MSF) and beyond. High data rate paths will also be required back (bi-directional) to the ASKAP site from other remote antenna installations around the continent as a demonstration for SKA. Initial AKSKAP BETA requirements are for a 1Gbps link expandable to several hundred gigabits per second using 10Gbps DWDM. The fibre choice (dispersion shifted G655) will enable expansion to 40Gbps and 100Gbps per wavelength for future SKA requirements.
Design study for a data transmission link
The Australian SKA Pathfinder (ASKAP) radio telescope project requires a new optical-fibre network connection from the Murchison Radio-astronomy Observatory (MRO) in the Mid-west of WA to a site in Geraldton. As the MRO is Australia's candidate site for the SKA, we plan to have sufficient fibre installed to meet the estimated needs of the SKA.
CSIRO has contracted AARNet to conduct a design study to define technical options for the project, make cost-benefit analyses for different options, design the fibre route, produce a detailed costing of the entire project, and analyse project risks. The study has now been completed, and an update on the data transmission project is available here.
This document is freely available and is being circulated to all parties who have expressed interest in ASKAP.
Please note that this document is not an invitation to tender. The procurement process will strictly follow the Commonwealth Procurement Guidelines.