Increase in Interference Levels in the 45 – 870 MHz Band at the Spanish e-CALLISTO Sites over the Years 2012 and 2019


Two sets of radio-frequency interference (RFI) measurements in the 45 – 870 MHz band are compared. The first set was taken in 2012 at various sites in the province of Guadalajara (Spain) as part of a worldwide site-testing campaign for the deployment of an international network of solar radio-spectrometers, the Compound Astronomical Low-cost Low-frequency Instrument for Spectroscopy and Transportable Observatory (e-CALLISTO) array. Peralejos de las Truchas was found to be an ideal location, even for high-sensitivity non-solar observations, with the lowest interference levels ever measured in the framework of e-CALLISTO. The same set of measurements have been repeated seven years later using the same experimental setup at the same locations. The results presented in this article show that the RFI levels after seven years have notably increased, at some places by a factor of two, thereby placing at risk broadband spectroscopic radio-astronomy studies from the ground.

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Our special thanks to the local authorities of Peralejos de las Truchas, the Castilla-La Mancha Science and Technological Park, and the University of Alcalá for supporting this work. We thank SSAA for travel support to carry out the first evaluation of a CALLISTO spectrometer host site in Spain. We thank Jonas Voit of D-PHYS/ETH for manufacturing and testing the spectrometer electronics and preparing the high frequency cabling. Finally, our sincere gratitude to Abel Moreno, our most valuable point of contact in Peralejos de la Truchas. This research work was partially funded by Ministerio de Economía y Competitividad (Spain), grant number ESP2017-88436-R.

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Correspondence to Manuel Prieto.

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Prieto, M., Gordo, J.B., Rodríguez-Pacheco, J. et al. Increase in Interference Levels in the 45 – 870 MHz Band at the Spanish e-CALLISTO Sites over the Years 2012 and 2019. Sol Phys 295, 11 (2020).

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  • Solar radio-astronomy
  • Solar radio-burst
  • Spectrometer
  • RFI