22 research outputs found
Real-Time Dedispersion for Fast Radio Transient Surveys, using Auto Tuning on Many-Core Accelerators
Dedispersion, the removal of deleterious smearing of impulsive signals by the
interstellar matter, is one of the most intensive processing steps in any radio
survey for pulsars and fast transients. We here present a study of the
parallelization of this algorithm on many-core accelerators, including GPUs
from AMD and NVIDIA, and the Intel Xeon Phi. We find that dedispersion is
inherently memory-bound. Even in a perfect scenario, hardware limitations keep
the arithmetic intensity low, thus limiting performance. We next exploit
auto-tuning to adapt dedispersion to different accelerators, observations, and
even telescopes. We demonstrate that the optimal settings differ between
observational setups, and that auto-tuning significantly improves performance.
This impacts time-domain surveys from Apertif to SKA.Comment: 8 pages, accepted for publication in Astronomy and Computin
Real-Time RFI Mitigation for the Apertif Radio Transient System
Current and upcoming radio telescopes are being designed with increasing
sensitivity to detect new and mysterious radio sources of astrophysical origin.
While this increased sensitivity improves the likelihood of discoveries, it
also makes these instruments more susceptible to the deleterious effects of
Radio Frequency Interference (RFI). The challenge posed by RFI is exacerbated
by the high data-rates achieved by modern radio telescopes, which require
real-time processing to keep up with the data. Furthermore, the high data-rates
do not allow for permanent storage of observations at high resolution. Offline
RFI mitigation is therefore not possible anymore. The real-time requirement
makes RFI mitigation even more challenging because, on one side, the techniques
used for mitigation need to be fast and simple, and on the other side they also
need to be robust enough to cope with just a partial view of the data.
The Apertif Radio Transient System (ARTS) is the real-time, time-domain,
transient detection instrument of the Westerbork Synthesis Radio Telescope
(WSRT), processing 73 Gb of data per second. Even with a deep learning
classifier, the ARTS pipeline requires state-of-the-art real-time RFI
mitigation to reduce the number of false-positive detections. Our solution to
this challenge is RFIm, a high-performance, open-source, tuned, and extensible
RFI mitigation library. The goal of this library is to provide users with RFI
mitigation routines that are designed to run in real-time on many-core
accelerators, such as Graphics Processing Units, and that can be highly-tuned
to achieve code and performance portability to different hardware platforms and
scientific use-cases. Results on the ARTS show that we can achieve real-time
RFI mitigation, with a minimal impact on the total execution time of the search
pipeline, and considerably reduce the number of false-positives.Comment: 6 pages, 10 figures. To appear in Proceedings from the 2019 Radio
Frequency Interference workshop (RFI 2019), Toulouse, France (23-26
September
High-Performance Computing for SKA Transient Search: Use of FPGA based Accelerators -- a brief review
This paper presents the High-Performance computing efforts with FPGA for the
accelerated pulsar/transient search for the SKA. Case studies are presented
from within SKA and pathfinder telescopes highlighting future opportunities. It
reviews the scenario that has shifted from offline processing of the radio
telescope data to digitizing several hundreds/thousands of antenna outputs over
huge bandwidths, forming several 100s of beams, and processing the data in the
SKA real-time pulsar search pipelines. A brief account of the different
architectures of the accelerators, primarily the new generation Field
Programmable Gate Array-based accelerators, showing their critical roles to
achieve high-performance computing and in handling the enormous data volume
problems of the SKA is presented here. It also presents the power-performance
efficiency of this emerging technology and presents potential future scenarios.Comment: Accepted for JoAA, SKA Special issue on SKA (2022
Fast Radio Bursts
The discovery of radio pulsars over a half century ago was a seminal moment
in astronomy. It demonstrated the existence of neutron stars, gave a powerful
observational tool to study them, and has allowed us to probe strong gravity,
dense matter, and the interstellar medium. More recently, pulsar surveys have
led to the serendipitous discovery of fast radio bursts (FRBs). While FRBs
appear similar to the individual pulses from pulsars, their large dispersive
delays suggest that they originate from far outside the Milky Way and hence are
many orders-of-magnitude more luminous. While most FRBs appear to be one-off,
perhaps cataclysmic events, two sources are now known to repeat and thus
clearly have a longer-lived central engine. Beyond understanding how they are
created, there is also the prospect of using FRBs -- as with pulsars -- to
probe the extremes of the Universe as well as the otherwise invisible
intervening medium. Such studies will be aided by the high implied all-sky
event rate: there is a detectable FRB roughly once every minute occurring
somewhere on the sky. The fact that less than a hundred FRB sources have been
discovered in the last decade is largely due to the small fields-of-view of
current radio telescopes. A new generation of wide-field instruments is now
coming online, however, and these will be capable of detecting multiple FRBs
per day. We are thus on the brink of further breakthroughs in the
short-duration radio transient phase space, which will be critical for
differentiating between the many proposed theories for the origin of FRBs. In
this review, we give an observational and theoretical introduction at a level
that is accessible to astronomers entering the field.Comment: Invited review article for The Astronomy and Astrophysics Revie
Fast Radio Bursts
The discovery of radio pulsars over a half century ago was a seminal moment
in astronomy. It demonstrated the existence of neutron stars, gave a powerful
observational tool to study them, and has allowed us to probe strong gravity,
dense matter, and the interstellar medium. More recently, pulsar surveys have
led to the serendipitous discovery of fast radio bursts (FRBs). While FRBs
appear similar to the individual pulses from pulsars, their large dispersive
delays suggest that they originate from far outside the Milky Way and hence are
many orders-of-magnitude more luminous. While most FRBs appear to be one-off,
perhaps cataclysmic events, two sources are now known to repeat and thus
clearly have a longer-lived central engine. Beyond understanding how they are
created, there is also the prospect of using FRBs -- as with pulsars -- to
probe the extremes of the Universe as well as the otherwise invisible
intervening medium. Such studies will be aided by the high implied all-sky
event rate: there is a detectable FRB roughly once every minute occurring
somewhere on the sky. The fact that less than a hundred FRB sources have been
discovered in the last decade is largely due to the small fields-of-view of
current radio telescopes. A new generation of wide-field instruments is now
coming online, however, and these will be capable of detecting multiple FRBs
per day. We are thus on the brink of further breakthroughs in the
short-duration radio transient phase space, which will be critical for
differentiating between the many proposed theories for the origin of FRBs. In
this review, we give an observational and theoretical introduction at a level
that is accessible to astronomers entering the field.Comment: Invited review article for The Astronomy and Astrophysics Revie