Correlation Software for eVLBI

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Correlation Software for e-VLBI

• Real-time fringe checking
• Craig West

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Fringe Checking Structure

• Record data onto disks
• Choose time to fringe check
• Transfer some data to central processor
• Perform fringe check on data
• Output results to webpage
• Allow for feedback...

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Current Status

• Working fringe checker
• Uses XF based checking with integration
• Detected fringes between
• Parkes, Narrabri, Mopra, Ceduna
• Currently two stand alone programs
• Data collection / Fringe checker
• Based on Swinburne Software Correlator!

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Example
Vela Pulsar - On pulse fringes - 4ms
PARKES-ATCA
PARKES-MOPRA
PARKES-CEDUNA
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Speed

• Dominated by data transfer time
• Can be reduced if sending to a telescope
• Currently XF correlation - fast enough
• Only need to fringe check on calibrator
• Fringe Rotation for long baselines
• Currently post fringe rotation

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Future versions...

• FX based fringe checking?
• Correct fringe rotation
• Real time data transfer
• Feedback from fringe checking into model
• Monitoring of Clock Rate drifts (EVN style)

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Information Exchange

• Time of data
• Clock rates
• Telescope used
• Sources observed
• What else is needed?
• When to fringe check? - Calibrators

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Timescales

• Working version?
• Trials?
• Telescopes?
• Correlator?
• Clock monitoring?