Radio Spectrum for Remote Sensing Primary Frequency Allocation Secondary Frequency Allocation Shared With Shared With Passive Services Only Passive Services Only but With Exceptions or Restrictions Shared With Active Services Shared With Active Services Shared With Active Services Acknowledgment of Spectrum Use Entitled to Radio Protection Entitled to Radio Protection Entitled to Radio Protection Entitled to Radio Protection From Secondary Users Brought into Use at a Later Stage May be Entitled to Radio Protection Monitoring and Enforcement of Spectrum Sharing and Coexistence Conditions FIGURE 8. The categories of radio spectrum use for remote sensing and respective entitlement to radio protection. (b) (a) (c) FIGURE 9. RFI presence probability maps of the European Space Agency Soil Moisture and Ocean Salinity mission, evidencing an RFI-free operational environment, over Portugal. (a) Continental Portugal, (b) Azores, and (c) Madeira. ACKNOWLEDGMENT The authors are grateful to the European Space Agency Soil Moisture and Ocean Salinity team responsible for RFI detection and reporting for the figures provided and for the excellent institutional cooperation established through the 286 years in solving harmful RFI cases affecting the mission. The authors would also like to acknowledge the Frequency Allocations in Remote Sensing Technical Committee (FARS-TC) chair, Roger Oliva Balague, for his support in preparing this contribution. Sandro Mendonça acknowledges support by IEEE GEOSCIENCE AND REMOTE SENSING MAGAZINE DECEMBER 2022