By : Arjun Radhakrishnan Supervisor : Prof. M. Inggs

 Pulsars and pulsar dispersion  Graphics Processing Units (GPUs)  Research method and Results  Conclusion and Future Work 2

 Pulsars are highly magnetised rotating neutron stars  They emit beams of electromagnetic radiation from their poles 3 Figure 1: A Pulsar with its ‘lighthouse’ beam [hartrao.ac.za]

 Pulsar emissions are distorted upon passing through the ionised Interstellar Medium (ISM)  Lower frequency components of the pulse are delayed more than higher frequencies

Figure 2: Dedispersion 2 5

 Class of consumer parallel processor that has come into use in the last 15 years  Use growing exponentially due to demand from billion-dollar video game industry  NVIDIA and AMD (ATI) are currently major players in the industry  GPUs do not have much on-chip memory – can pack in lots of compute power 6

 Justification for SKA  Large frequency range  1TB of data per minute  SKA needs real-time processing as data storage is not feasible  No communication needed between GPU kernels 7

 Worked at UIUC on the QP GPU cluster  Implemented the following coherent pulsar dedispersion algorithm 4 :  Fourier transform input signal  Apply a phase rotation  Inverse Fourier transform 8

 Code testing is still being conducted  Some trends noted are:  Speedup of up to 5x over CPU implementation  Performance improved approximately linearly with the number of GPUs used  Best performance for larger datasets (minimises effect of IO bottleneck) 9

 GPUs definitely show promise in this application  Further speedup may be possible by using an asynchronous data transfer  Analyse the network requirements and limitations when deployed 10

1. Cordes & McLaughlin (2003), “Searches for Fast Radio Transients”, The Astronomical Journal, vol. 596, pp Jim Cordes, “The SKA as a Radio Synoptic Survey Telescope: Widefield Surveys for Transients, Pulsars and ETI”, SKA Memo NVIDIA, NVIDIA CUDA Programming Guide 4. Walter Brisken, “Real-time Digital Signal Processing for Radio Astronomy” AstroGPU 11

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