Current LBA Developments Chris Phillips CSIRO ATNF 13/7/2005.
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Transcript of Current LBA Developments Chris Phillips CSIRO ATNF 13/7/2005.
![Page 1: Current LBA Developments Chris Phillips CSIRO ATNF 13/7/2005.](https://reader035.fdocuments.in/reader035/viewer/2022062801/56649e175503460f94b02832/html5/thumbnails/1.jpg)
Current LBA Developments
Chris PhillipsCSIRO ATNF
13/7/2005
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Disk Based Recording
• Thanks to initial work by Uni of Tasmania and Swinburn Uni, the LBA has disk based recorders at all Australian stations & NZ
• Based on Metsähovi “VSIB” digital input card– “PCEVN”
• Have just ordered 10 systems for uniformity across LBA
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System Setup
• LBA DAS for sampling and digital filtering– Produces up to two 16 MHz bands for 2 IFs– 256 Mbps data rate– Parkes, Mopra and ATCA have 2 DAS (512
Mbps)
• MRO “VSIC” converts S2 input data into VSI-H format
• MRO “VSIB” PCI card used for data input into standard PC
• Data recorded onto disk using normal Linux filesystem
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Recorder PC setup• Dual processor (AMD64 )Tyan motherboard• Dual onboard gigabit Ethernet• Primary disk recording into Apple Xserve
RAID– 14 400 GB disks in RAID5 configuration
• 4 400 GB removable IDE (PATA) disks in software RAID configuration for compatibility– Running on Promise Ultra133 TX2
• Also 2 400 GB internal SATA disks– 4 onboard SATA-II connectors
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Recorder Costs
• PC with 800 GB disk space– €2410 ($A3890)
• VSIB+VSIC input cards– €1090
• Apple Xserve RAID with 5.6 TB disk space– €9900 ($A1600)
• 4x400 GB IDE PATA disks– €1014 ($A1640)
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Why Not Mark5?
• Mark 5a not compatible with LBA DAS– MRO systems engineered to work with S2
data format
• MRO system better suited to software correlation– Data recorded using normal Linux
filesystems
• Cost is similar to Mark5– Apple Xserve RAID is major component
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Huygens VLBI Experiment
• Intended to be Mark5– Not compatible with LBA (Parkes, ATCA,
Mopra, Ceduna)
• Installed second DAS for experiment• Produced special cable to record data
from 2 DAS onto one disk recorder
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Real Time Fringe Testing
• Suite of networked Perl scripts allow almost realtime interactive fringe testing
• 0.5-1 seconds of data transferred to Swinburne to correlate in software– Limited by slow networks,
• 512 kbps for ATCA, Parkes• 33kbps modem for Hobart!
• Can get fringes within 30sec– Usually a couple of minutes
• Routinely run for all LBA experiments
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Observations to Date
• First full LBA test experiment in April04– Including Hart, VLBA, Kashima (Mk5, K5)
• Also Nov04, May05• Tests to NZ • Huygens experiment and Huygens tests• High spectral resolution of OH masers
– 4 MHz, 16000 channels
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Disk VLBI Availability
• Disk based recording added as option for OCT05 observing session– Shared risk basis
• Data recorded at rates up to 512 Mbps– Possibly up to 1 Gbps
• Will be correlated using Swinburne software correlator
• Suitable for sensitive observations, high spectral resolution, pulsar coherence dedispersion etc
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Future Developments
• MRO systems are not compatible with ATNF S2 correlator– Delay tracking performed by S2 playbacks
• All disk & eVLBI correlation using Swinburne software correlator– May be able to do disk S2 copying
• On-going project to record 2x64 MHz bands from DAS (512 Mbps)– Currently problem with clocking
• 2x16 MHz 8bit (or 10bit)
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eVLBI
• Recorders equipped with dual onboard gigabit Ethernet
• Suitable for 512 Mbps transfer• Initially record and transmit, then
remote recording• Will experiment with realtime software
correlation– Initially single baseline– Possibly to Uni of Western Australia
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Long Term Plan
• New correlator being developed for ATCA– Based on FPGA digital filterbanks
• Plan to use as VLBI correlator– Should handle data rates up to 64 Gbps
• 2 GHz, 2 Pol, 8 bit