AGENDA ITEM 1.25: ADDITIONAL MOBILE-SATELLITE SERVICE IN THE BANDS 4-16 GHZ

To consider[s] possible additional allocations to the mobile-satellite service, in accordance with Resolution 231 (WRC 07).

ITU-R studies are focusing on the following frequency bands for which detailed technical compatibility or sharing analysis are yet to be made (see Table 2.10).

Radio Astronomy Service

The primary concern for Radio Astronomy is that the frequency range 4-16 GHz contains the following RA bands: 4800-4990 MHz (secondary), 4990-5000 MHz (primary), 10.6-10.7 GHz (primary) and 15.35-15.4 GHz (primary). Nearly all centimeter wavelength radio telescopes operate in the 4800-5000 MHz band to study the continuum radio emission from stars, galaxies, quasars, gamma-ray bursts and other sources of galactic and extragalactic thermal and non thermal continuum radiation. The downlink in the 5150-5250 MHz band is close to the 4990-5000 MHz passive band used for continuum studies of galactic and extragalactic sources.

Recommendation: Satellite downlink transmissions should have low enough out-of-band emissions to minimize interference with radio astronomy based on Recommendation ITU-R RA.769. This applies to uplinks as well, though if well separated from observatory sites, uplinks are unlikely to cause interference.

Earth Exploration-Satellite Service

The primary concern for Remote Sensing is that the frequency range 4-16 GHz contains the 10.6- 10.7 GHz EESS (passive) allocation as well as the bands near 7 GHz in use by current assets. These bands are used for a number of EESS applications including observations of soil moisture, sea surface temperature, sea surface height, sea ice, snow, and precipitation. Measurement of these geophysical parameters is critically important to weather prediction, climate monitoring and understanding changes in the global water cycle. Current spaceborne radiometers observing Earth in 10.6-10.7 GHz suffer from interference making the data unusable in certain areas, e.g., over the Mediterranean Sea, due to satellite s-E transmissions reflected off the ocean surface.1 Additional passive bands of interest include the spectrum near 6.8 GHz to measure soil moisture (SM) and sea surface temperature (SST). (See also agenda item 8.2) NASA’s EOS Aqua carries the Japanese AMSR-E radiometer measuring in 350 MHz at 6.925 GHz and the Navy’s WindSat radiometer measures in 130 MHz at 6.8 GHz. The U.S. Joint Polar-orbiting Satellite System (JPSS) will use band(s) between 5-8 GHz to monitor SST and SM, both of which strongly affect the weather and climate. Because of the microwave physics this frequency range is the best for measuring SST and is very practical for measuring soil moisture. International Footnote 5.458 urges “Administrations [to] bear in mind the needs of the Earth exploration-satellite (passive) and space research (passive) services in their future planning” of this frequency range. Indeed, actions affecting this frequency range should be considered carefully so its use by EESS (passive) is preserved.

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1 National Research Council, Spectrum Management for Science in the 21st Century, The National Academies Press, Washington, D.C., 2010, pp. 67-72.



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