GPU-based real-time RFI identification and mitigation

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The purpose of this work to implement GPU-based RFI identification and mitigation techniques for the GBT VEGAS spectrometer / pulsar backend. Initial tests are being performed as part of the Pulsar Timing RFI Mitigation Pilot Project, which is using archival GUPPI raw voltage data observations of millisecond pulsar J1713+0747. This work is being performed as part of the Software Enabled Radio Astronomy (SERA) project.

While the main goal is to implement real-time RFI mitigation for VEGAS, we have a number of subsidiary goals, including:

  • perform general research into real-time RFI mitigation techniques,
  • Make our results and algorithms available for the general community, via the SERA and CASPER projects
  • Utilize this problem domain as a target for research into improved design of heterogeneous computing systems, in particular in association with the University of Maryland DSPCAD Research Group and the NIST Hybrid Graph Task Scheduler project.

J1713+0747 Channel 23 Mitigation Example

J1713+0747 Channel 23 TOA Analysis

'For details of current work, skip straight to the Pulsar Timing RFI Mitigation Pilot Project page.

Project Background

Radio Frequency Interference (RFI) - any unwanted terrestrial signal which is present in our data - is a significant and growing problem for radio astronomy research. There are many potential solutions, depending on the telescope, and situation. The goal of this project is to implement GPU-based real-time RFI identification and mitigation for the Green Bank Telescope (GBT) 'VEGAS' CASPER-based spectrometer / pulsar backend.

Our focus is specifically on single-dish radio telescopes, with the GBT as the primary target. At a meeting held in Socorro, NM, in October 2016, we identified three science areas which would particularly benefit from real-time mitigation:

  • Pulsar timing observations made using the coherent de-dispersion and folding observing mode;
  • Observations of the neutral hydrogen (HI) line in galaxies at high redshift (z ~ 1) so the rest frequency of 1420 MHz is observed at topocentric frequencies around 700 MHz,
  • SETI observations

Of these topics, the problem of RFI mitigation for SETI observations is being tackled by the Breakthrough Listen project. We are investigating the pulsar timing problem as part of the Pulsar Timing RFI Mitigation Pilot Project, in collaboration with Michael Lam at WVU. We also plan to tackle the high redshift HI case, in collaboration with D.J. Pisano and Lucase Hunt, also at WVU, in due course.

Project Team - Summer 2017

We have a number of students who will work on this project over summer 2017. As of May 2017, the people most active on the project are:

  • Kingsley Enoka, Summer Student, West Virginia University
  • Luke Hawakins, Digital Engineer, Green Bank Observatory
  • Nick Joslyn, REU Student, Simpson College, Iowa
  • Richard Prestage, Scientist Green Bank Observatory, ````Project Lead'
  • Emily Ramey, REU Student, Washington University, St. Louis
  • Natalia Schmid, Professor, West Virginia University
  • Steve White, Head of Electronics, Green Bank Observatory
  • Mark Whitehead, Head of Software Development, Green Bank Observatory

We also either are already, or hope to collaborate more or less closely with the following individuals:

  • Kevin Bandura, Professor, West Virginia University
  • Shuvra Bhattacharaya, Processor, University of Maryland
  • Tim Blattner, NIST, USA
  • Kaushal Buch, Engineer, GMRT, NCRA, India
  • Lucas Hunt, Graduate Student, West Virginia University
  • Walid Keyrouz, NIST, USA
  • Michael Lam, Post-doc, West Virginia University
  • D.J. Pisano, Professor, West Virginia University
  • Cedric Viou, Station de Radioastronomie de Nançay, France
  • Dan Werthimer, Chief Scientist, SETI / PI, CASPER, U.C. Berkeley

Weekly Meeting

Monday's 10:00am GB-Basement GPU Mitigation Weekly Meeting

Mailing List

We have our own mailing list: For more information, see the list List Archive page. If you would like to be added to the mailing list, send a request to


  • BTL - Breakthrough Listen (a SETI project)
  • CASPER - Collaboration for Astronomical Signal Processing and Electronics Research:
  • DFT - Discrete Fourier Transform
  • DSP - Digital Signal Processing
  • FFT - Fast Fourier Transform
  • GBT - Green Bank Telescope
  • GUPPI - Green Bank Ultimate Pulsar Processing Instrument
  • MAD - Median Absolute Deviation
  • SERA - Software Enabled Radio Astronomy:
  • VEGAS - Versatile GBT Astronomical Spectrometer

Summer 2017 Summary Information

Additional Information and Background Links

Details on the actual pulsar timing work are available at the Pulsar Timing RFI Mitigation Pilot Project page.

The following links provide additional useful background information related to this project:

Project Specific Links

GUPPI Raw Data

RFI Literature

There is a vast amount of literature regarding RFI and RFI mitigation.

This is a link to a list of papers: [RFI Literature]

This is a link to an annotated bibliography of some of those papers (and others): [Annotated Bibliography]. Update as necessary and alter the authorship to reflect the changes. This is an Overleaf document which utilizes LaTeX.

General Links