Long baseline Array (LBA) Telescopes in Australia –ATNF, U.Tasmania, NASA –core Oz VLBI network + South Africa + Telescopes in Asia Pacific region –Japan, China, Hawaii, VLBA(west),… Asia Pacific Telescope (APT)
LBA - S2 system Canadian S2 VCR-based recorder –8 VCR recorders 128 Mbps max data rates 7-station LBA correlator at ATNF Sydney –XF architecture (ATCA correlator design) –Max 16 MHz channels (2-bit) –Spectral line system (2k+ channels) –Very configurable –(visits can be arranged during workshop) Remains the main production-VLBI system –No plans to upgrade correlator –S2 maintenance issues (no external support) Phase-out within ~3-4 years?
LBA - DAS DAS: Based on Digital Filters –2 input IFs @ 64 MHz BW (2 pols or 2 frequencies) –Sampling (10 bits) + Digital filters (ideal passbands) –Bands: 64MHz 125 KHz –S2 mode: 2 x 16 MHz ( 128 Mbps to match S2) –Huygens mode: 4 x 16 MHz (256 Mbps) –Maximum: 2 x 64 MHz (512 Mbps) –Multibit mode: 2 x 16 MHz x 8(10) bits 512 Mbps Interference excision? ATNF stations: 2 DAS units –512 Mbps for Huygens –1 Gbps with 64 MHz channels (under development) Remains the main DAS for LBA systems (tapes or disks)
LBA - Operations Open network EVN model of operation Limited support - 1 correlator operator Schedules via VLBA SCHED Information on systems and proposals: –http://www.atnf.csiro.au/observers/ –http://www.atnf.csiro.au/vlbi New: Array sensitivity calculator
LBA - Disk recorders (See C. Phillips talk for details) PCEVN-Metsahovi VSI interface system –VSIC (ECL-LVDS) & VSIB(computer) –Connects to LBA DAS –All LBA antennas equipped COTS server-class computers –Dell 1600SC servers (test systems) –New dual CPU machines ordered –X-RAID hardware RAID systems –IDE disks & software-RAID - PATA disks
Software correlators See talks by S. Tingay & A. Deller Swinburne Supercomputer – > 100 Dell computers in cluster –Much slower than real time? Cray XD-1 supercomputer in WA –Under development –Approach real-time operation? XF & FX software versions Only Oz correlators for disk systems
New LBA National Facility capability Limited National Facility observing offered in 2005OCTS with: – disk-based systems + software correlation Limits: –Disk availability –Software correlator time Technical details at: –http://www.atnf.csiro.au/vlbi/documentation/VLBI_ National_Facility_upgrade.html
LBA support for Huygens See C. Phillips talk Spacecraft tracking of Huygens probe descent onto Titan (14 January 2005) LBA 512 Mbps disk system development Software correlation underway at JIVE Huge publicity for VLBI Limited e-VLBI - delayed network transmission ATNF JIVE Demonstrated need for global e-VLBI connectivity
Real-time fringe testing Disk-system runs parallel to S2 VCRs –S2 C2 output port ~0.1 sec data acquired Transfer to Swinburne - (slow) ftp Correlate and post on web –Within a few minutes –Record fringe in ~30secs Semi-automatic operation Routine for all LBA observations –Monitor fringes for all calibrators Increased LBA reliability and robustness
The Future? e-VLBI –CABB Hardware Correlator –Network Connectivity
CABB Correlator See talk by w. Wilson Broadband upgrade of ATCA –VLBI capability added 4 Gsamples x (8) bits 32 Gbps streams – 4 IFs per antenna – 8 antennas Digital Polyphase filters ATCA operation in 2007 - VLBI?
Multiple Zoom (>2 possible) Compound Zoom Simple Zoom Basic Configuration FFT FIR Filterbank Fringe Rotators Correlator s DMUX A 2GHz bandwidth polyphase digital filterbank with 4096 channels...... will fit into four XC2V6000 FPGAs FPGA hardware may be completely reprogrammed to produce many different filterbank configurations, as different observations may require. RF, IF and Baseband Signal Path Filterbank Architecture A Wideband Upgrade for the Australia Telescope Compact Array Luneburg Lens Phased Array 6 * 22m antenna AT Compact Array
Network connectivity See talks by K. Burston & G. McLaughlin AARNet3 Regional Network Fibre tails to ATNF antennas in 2005 –$2M project, awaits final CSIRO approval 1 Gbps connectivity at start 10 Gbps (x multiple wavelengths) backbone Multiple 10 Gbps streams to CABB correlator Good international connectivity Future: -switching?