The DiFX software correlator
DiFX is an FX-style correlator developed in C++, optimized for performance using Intel vector libraries. Designed for commodity clusters, it enhances accessibility to complex correlator parameter spaces, now utilized by LBA and VLBA. The new functionality increases spectral and temporal resolution, with capabilities for flexible pulsar processing and support for higher data rates. Future enhancements include the use of multiple phase centers, improving survey speed and addressing demanding applications in astrophysics. With modest investment, DiFX significantly boosts throughput and efficiency for next-gen radio astronomy.
The DiFX software correlator
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Presentation Transcript
The DiFX software correlator • DiFX is an FX style correlator written in C++ • Designed to run on commodity clusters • Optimised Intel vector libraries are used for good performance • Makes hard-to-reach areas of correlator parameter space accessible • Now used by LBA, VLBA and (soon) AuScope, MPIfR (Bonn)
DiFX at the VLBA • Acceptance testing is all but complete - correlator switchover by end of year (call for proposals already made in October) • Investment has been modest: 10 node cluster costing ~$25,000 enables throughput of ~500 Mbps/antenna for 10 stations (roughly double the hardware correlator)
VLBA DiFX verification Visibility phase vs time:Colors are a little hard to see: blue is HWC, purple is SWC, cyan is where they overlap perfectly
New VLBA functionality: now • Much increased spectral and temporal resolution: in principle almost infinite, in practice at least 16x previous is offered • Much more flexible pulsar processing; previously only an on/off gate available • Ability to process data in previously inaccessible formats (like the higher datarate Mark5B/B+)
Future features: Multiple PCs • At any given instant, the phase centre (PC) of correlation can be changed by rotating the visibilities by a phase value equal to the sky frequency x delay (between desired phase centre and current phase centre) • When done in-correlator,very high spectral andtemporal resolution meansalmost no smearing primary beam uv-shifted “pencil” fields
Future features: Multiple PCs • At low frequencies (and high sensitivity) there will be many sources per primary beam • Thus a dramatic improvement in survey speed! • Applications in in-beam calibrator searches, star-formation regions, galaxy evolution studies and more
