A Strategy for Active Remote Sensing Amid Increased Demand for Radio Spectrum (2015) / Chapter Skim
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Measurements in this range have direct societal benefits. Active remote sensing measurements can be either transmission measurements, in which the transmit and receive antennas usually point at each other; or scattering measurements, where the transmitted signal reflects from the medium and is received by an antenna colocated with the transmitter (the backscatter mode)
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Specific examples of the importance of different types of active remote sensing measurements to science and society include these: • Active remote sensing of the atmosphere can save lives and protect property from severe storms, as well as provide a deeper understanding of upper atmospheric winds and global circulation to scientists. • Active microwave sensors provide unique measurements of ocean cur rents, waves, and wind speed and direction and are complementary to pas sive microwave and visible and infrared (IR)
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Current and Future Threats to the Effective Use of Spectrum Required for Active Remote Sensing In all cases the frequencies utilized by active remote sensing are determined by the physics of the phenomena that are being studied. The frequencies were carefully chosen to best reveal the underlying physics, and in most cases considerable expense has been incurred in facilities and technology to operate in the chosen frequency range.
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Specific examples of current interference and potential future interference include these: • In several cases, transmit restrictions imposed on active science sensors have significantly impeded the ability to collect the desired science data (as in the operational restrictions imposed on the European Space Agency's [ESA's] BIOMASS mission)
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It should also be noted that one of the difficulties with characterizing the impact of RFI on active remote sensing space instruments is the incompleteness of information regarding current emitters world-wide, as well as the evolving nature of the RFI environment over time. There is currently a lack of good metrics for quantifying the degradation of science measurements for the full variety of active instrument types (e.g., scatterometers, altimeters, SARs, interferometers, and sounders)
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opportunities for spectrum sharing; and (5) rec ommended increases in the spectrum allocated for scientific active remote sensing.
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(Recommendation 8.1) • NASA should lead a community effort to construct a set of metrics that relate to the various RFI environments encountered and the associated degradation in science performance for each major class of instruments employed in active remote sensing.
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Recommended Increases in the Spectrum Allocated for Scientific Active Remote Sensing Some modest increases in spectrum allocations for scientific active remote sensing would be highly beneficial: 2 Femtocells are discussed in Chapter 9.
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The FCC should reinstate an experimental licensing process for CODAR to allow for future engineering research advances and exploratory science advances. (Finding 3.2 and Recommendation 3.2)
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