Operational Data Sharing for RFI Mitigation

With the rise of Low-Earth Orbit (LEO) satellite constellations, potential harmful downlink satellite interference is detrimental to the radio telescopes located in remote locations. In the past few years, NRAO has been developing an autonomous reporting system, the Operational Data Sharing (ODS), to inform satellite operators of our telescope operation parameters. Through the ODS API, the satellite operators will query the telescope data (e.g., based on the VLA Scheduling Blocks) to perform mitigation measures when they are orbiting above or placing downlink beams near the telescope. 

ODS, when operational - and in conjunction with a satellite operator, currently SpaceX’s Starlink, that can redirect or turn off beam forming electronics for brief periods of time - allows radio telescopes to observe in the 10.7-12.7 GHz band (upper X-band into lower Ku band) without experiencing disruptive or potentially damaging radio frequency interference (RFI). NRAO has also begun testing the same ODS framework for use with Direct to Cell (DtC) downlink frequencies falling within the 1990-1995 MHz range (L or S-band).  

Currently the ODS reporting process is done behind the scenes for the observers. Any SBs submitted through the OPT system will be reported. For further information, please visit the ODS webpage.

There are two primary goals for the ODS:

  1. Protect telescope's frontend electronics and digital backend from compression caused by potential strong satellite downlink signal.
  2. Regain possible clean spectrum window when TBA is engaged.

Even with the TBA in place, as an additional layer of protection from out-of-band emission or compression in the frontend or digitizer, we highly recommend the observers not to set a subband overlapping the 1990-1995 MHz when using the L- or S-band receiver, if not needed. This will ensure extremely strong RFI from the DtC will not affect the entire baseband.

Disclaimer: The current ODS system is still under development, hence no guarantee can be made on completely clean spectrum from the Starlink downlink at 1990-1995 MHz and 10.7-12.7 GHz. Although our team does periodic verifications of the TBA on randomly selected measurement sets, we highly encourage the PIs and observers to report unexpected RFI within the two TBA bands.

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The NSF National Radio Astronomy Observatory and NSF Green Bank Observatory are facilities of the U.S. National Science Foundation operated under cooperative agreement by Associated Universities, Inc.

Founded in 1956, the NSF NRAO provides state-of-the-art radio telescope facilities for use by the international scientific community. NSF NRAO telescopes are open to all astronomers regardless of institutional or national affiliation. Observing time on NSF NRAO telescopes is available on a competitive basis to qualified scientists after evaluation of research proposals on the basis of scientific merit, the capability of the instruments to do the work, and the availability of the telescope during the requested time. NSF NRAO also provides both formal and informal programs in education and public outreach for teachers, students, the general public, and the media.

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