Message 13/504 Steve Parsley Oct 17, 2000 11:13:49 am +0100 Date: Tue, 17 Oct 2000 11:13:49 +0100 To: Subject: EVNtech: JIVE fiber developments for TOG Content-Disposition: inline Sender: owner-evntech@jb.man.ac.uk Precedence: bulk X-MIME-Autoconverted: from quoted-printable to 8bit by newton.astro.uni.torun.pl id LAA00496 FIBRE DEVELOPMENTS - PILOT EXPERIMENTS TOG TORUN OCT 2000 Steve Parsley - 13 October 2000 JIVE is at the very early stages of planning an EVN pilot Project to examine the possibility of real-time connected VLBI using fibre-optic links. Current costs are prohibitive but plans to create a pan-European gigabit research network (Geant) could make such a system affordable in the future. The pilot project is needed now to ensure that we are ready, when the time comes, to grasp whatever opportunities may arise. Benefits - Wider bandwidth - Gain in sensitivity - Better reliability - Better time efficiency - Easier data "logistics" - Lower operating costs at both stations and processing centre - Near real-time results - More effective network monitoring Objectives To be useful the pilot experiments should gather experience and knowledge which will enable the magnitude of full-scale implementation to be evaluated. Ideally the pilot will yield real designs which can be adapted and replicated for the full network. To this end the project should: - Establish relations with suitable network providers - Identify potential hardware and software for acquisition unit and data processor receiver - Establish interfaces to signal sources and correlator - Evaluate the relationship between the design of a fibre connected system and the design of future correlators - Prepare software interfaces to field system and correlator control - Understand logistical and administrative requirements The pilot should also attempt to yield some new scientific astronomical capability if possible. High resolution spectroscopic VLBI, multi-bit signal sampling and continuous delay tracking are possible candidates. Initially we set a target of four stations, each delivering 64Mbit/s comprising 4 X 2-bit channels at 8Mhz bandwidth or multi-bit sampling for narrower bandwidths. Implementation The initial aim will be to use commercial, off-the-shelf (COTS) products. Very high speed, industry standard backplanes are becoming available. A system built from high specification A/D, digital I/O and DSP boards seems plausible. With the addition of one custom module to realise a VLBI Standard Interface (VSI) a self contained acquisition unit can be developed. Initially this can be done without commitment to any particular form of network connection. A unit built on similar principles can be developed to receive data at JIVE and interface to the correlator. Some commonality between the acquisition unit and the processing centre units may be possible. There is also potential to look at other developments such as DSP correlation and station based fringe stopping in such a unit. The project will pay close attention related developments such as eMerlin at Jodrell Bank, the THEA and ALMA back-ends at NFRA, and COTS HDR at Haystack. Timescale Three to four years elapsed time is envisaged. One year will be spent researching available hardware, software and development facilities. One to two years should be enough to design and build laboratory units. The final year will be used to replicate and deploy the station-based equipment and to run the trial. In parallel with this details of the network connection must be worked out. Budget Order of magnitude estimates indicate 20my labour and 500kEuro material cost.