Views of the U.S. National Academy of Sciences and National Academy of Engineering on Agenda Items at Issue at the World Radiocommunication Conference 2012 (2013) / Chapter Skim
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2 Views of the U.S. NAS and NAE on WRC-12 Agenda Items
2 Views of the U.S. NAS and NAE on WRC-12 Agenda Items
Pages 8-39
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2 Views of the U.S. NAS and NAE on WRC-12 Agenda Items The following pages provide a discussion of the committee's consensus opinion on the potential impact and relevance of certain agenda items at issue at the upcoming World Radiocommunication Conference (WRC)
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It must also limit narrow band spurs to peaks no more than 11 dB above this average level in any 50 kHz channel within the RAS band, in order to conform to the corresponding spectral line level of –230 dBW/m2/Hz specified in Recommendation ITU-R RA.769. Recommendation: Transmissions in support of unmanned aircraft in the 5030-5150 MHz band should have sufficiently low level of unwanted emissions to avoid interference in the adjacent Radio Astronomy Service bands, in accord with Recommendation ITU-R RA.769.
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Recommendation: Transmitters providing surface applications at airports in the 5000-5030 MHz band should have sufficient suppression of out-of-band emissions to avoid interference in the adjacent 5 GHz Radio Astronomy Service band in accord with Recommendation ITU-R RA.769.
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. Because of high atmospheric absorption of signals due to water vapor above 1 THz, ground-based observations can only be made from extremely high sites, usually above 3 km.
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-3(2,2) 646 fractionation CH 1-0 537 Important chemical building block, 2-1 1477 tracer of diffuse gas OH 1-0 2560 Star formation, O-rich evolved stars Metal hydrides 1-0 Various Interstellar coolants (SiH, LiH, MgH, 2-1 Building blocks of interstellar NaH, AlH)
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for O3, CH3Cl, N218O, BrO, ClO 523-527 4 000 Window for 556.9 Wing channel for water vapor sounding Window (523-527) 538-581 43 000 {541.26, 542.35, 550.90, Water vapor sounding Odin 556.98} (HNO3)
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, 660.49 (HO2) , Water vapor sounding, cloud CIWSIR, MWI, 688.5 (CH3Cl)
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TABLE 2.3 Typical EESS Uses of Spectrum from 275 to 3000 GHz Use/Measurement/Target Significance Mapping of ozone, polar Three-dimensional (3D) mapping of ozone in the stratosphere to stratospheric clouds, chlorine understand current ozone distribution and mechanisms for its sources depletion Cloud ice and frozen precipitation Key variable in the understanding of the water cycle, Earth's energy budget, and the effect of cloud feedback on the climate, viewed in window regions around absorption features from gaseous constituents Upper troposphere and stratospheric Key aspect of the water cycle and important for determining climate water vapor feedback effects on radiative forcing in the presence of increasing greenhouse gases.
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service, and to take appropriate action on this subject, while retaining unchanged the generic allocation to the mobile-satellite service in the bands 1,525-1,559 MHz and 1,626.5-1,660.5 MHz. The primary concern for Radio Astronomy is the passive band from 1660 to 1670 MHz, which is shared with other services and is used to investigate phenomena associated with the formation of stars marked by maser emission from the hydroxyl radical (OH)
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Thus, this region is rich in spectral lines and high spectral resolution can be achieved, as shown in Figure 2.1. Millimeter molecular lines in the 71-238 GHz bands serve as important probes of dense gas in a wide variety of astronomical settings.
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of the Arizona Radio Observatory using a single-sideband (SSB) receiver covering a 1 GHz band.
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NOTE: Important transitions also exist in the frequency range 238-275 GHz, for example, the J = 3 → 2 transitions of HCN and HCO+. This region is used for both filled aperture spectroscopy and imaging, and covers several of the prime bands for ALMA: Band 3 (84-115 GHz)
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Global water vapor profiles are essential to the numerical weather prediction of rainfall and drought and help constrain such predictions in general. 2 Water vapor is the primary mechanism for energy storage and its movement within the atmosphere as it drives extreme weather events.
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To protect EESS satellite observations from interference, ITU-R RS.1029 recommends a maximum interference level in the 22.21-22.5 GHz band of −249 dBW/Hz, with this interference level not to be exceeded for more than 0.1 percent of the sensor viewing area or measurement time. In this band, ITU Radio Regulations Footnote 5.149 states that "administrations are urged to take all practicable steps to protect the radio astronomy service from harmful interference.
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To protect EESS satellite observations from interference, ITU-R RS.1029 recommends a maximum interference level in the 22.21-22.5 GHz band of −249 dBW/Hz, with this interference level not to be exceeded for more than 0.1% of the sensor viewing area or measurement time.
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Emissions from spaceborne or airborne stations can be particularly serious sources of interference to the radio astronomy service." This band is needed to distinguish between water vapor content and liquid cloud content and also constitutes an essential part of measurements of ocean wind speed, snow cover depth on land, as well as sea ice type, age and temperature. Measurement of these geophysical parameters is critically important to weather prediction, climate monitoring and understanding changes in the global water cycle.
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recommended a maximum interference level in the 36.0-37.0 GHz band of −246 dBW/Hz, with this interference level not to be exceeded for more than 0.1% of the sensor viewing area or measurement time.
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Earth Exploration-Satellite Service The primary concern for EESS is that the proximity of 21.4-22.0 GHz to the 22.21-22.5GHz 5band increases the risk that out-of-band emissions will interfere with Earth observation of atmospheric water vapor. To protect EESS satellite observations from interference, ITU-R RS.1029 recommends a maximum interference level in the 22.21-22.5 GHz band of –249 dBW/Hz, with this interference level not to be exceeded for more than 0.1% of the sensor viewing area or measurement time.
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2 Passive measurements from EESS satellites near the water vapor absorption line at 22.2 GHz are essential not only for measuring atmospheric water vapor but also for reducing error in other geophysical parameters due to the presence of water vapor, especially in moist atmospheres. For example, the accuracy in measuring sea surface wind speed, sea surface temperature, liquid cloud water or precipitation would significantly degrade if the 22 GHz water vapor channel was not present or unusable due to RFI contamination.
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At this distance the typical path loss due to scattering is about 195 dB at 73 MHz. Recommendation: Additional radiolocation service allocations in the 30-300 MHz band being considered should avoid the 37.50-38.25 MHz, 73.00-74.60 MHz and 150.05-153.0 MHz passive bands, and should provide suppression of unwanted emissions in these radio astronomy service bands to meet Recommendation ITU-R RA Rec.769.
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Radio Astronomy Service The primary concern for Radio Astronomy is the Radio Astronomy Service (RAS) bands in the 350 MHz range (which include 13.36-13.41, 25.56-25.67 and 37.50-38.25 MHz)
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out to sea they will need to be sure their antenna backlobe is down by 50 dB to avoid interfering with the LWA in New Mexico. Recommendation: Unwanted emissions due to new radar allocations the 3-50 MHz range should be low enough to meet the levels of Recommendation ITU-R RA.769 in the Radio Astronomy Service bands at 13.36-13.41, 25.56-25.67 and 37.50-38.25 MHz.
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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. If enacted in full, this agenda item could impact radio astronomy in the 4800-5000 MHz band as a result of second harmonic radiation.
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From page 31... ...
allocations -- do not result in increased levels of interference to RAS or EESS through unwanted emission. Recommendation: Representatives of the Radio Astronomy Service and Earth Exploration-Satellite Service spectrum management communities should be included in deliberations that might lead to the establishment of universal "beacon" or "pilot" channels, "dynamic databases," and other technologies intended to facilitate "dynamic spectrum access" or dynamic changes in other emission characteristics including modulation type, bandwidth, and power levels.
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Earth Exploration-Satellite Service The primary concern for EESS is Earth remote sensing satellites currently use, and will continue to use, spectrum near 6.8 GHz to measure soil moisture (SM) and sea surface temperature (SST)
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Recommendation: Spectrum selected for high altitude platform stations gateway links should avoid frequencies used for Earth observation by current and planned remote sensing satellites in accordance with Footnote 5.458.
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Recommendation: Radar in the 15.4-15.7 GHz band should have a sufficiently low level of unwanted emissions to avoid interference in the adjacent 15.35-15.40 GHz Radio Astronomy Service/Earth Exploration-Satellite Service band in accordance with the limits specified in Recommendation ITU-R RA.769. 1 Resolution 614 is to study, as a matter of urgency, the technical characteristics, protection criteria, and other factors to ensure that radiolocation systems can operate compatibly with systems in the aeronautical radionavigation and fixed-satellite services in the band 15.4-15.7 GHz, taking account of the safety nature of the aeronautical radionavigation service; to study, as a matter of urgency, the compatibility between the radiolocation service in the band 15.4-15.7 GHz and RAS in the adjacent band 15.35-15.40 GHz.
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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 sE transmissions reflected off the ocean surface.1 Additional passive bands of interest include the spectrum near 6.8 GHz to measure soil moisture (SM)
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services in their future planning" of this frequency range to protect current and future spaceborne observatories.
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This has become a key means to understand the effects of changes in both the natural and artificial environment and to provide information for effective decision-making and resource management in many areas of our society and lives. In addition, remote sensing science and technology have economic benefits, both in job creation and in early warning of potentially disastrous and disruptive situations.
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In addition, Earth science and observation technology have economic benefits, both in job creation and in early warning of potentially disastrous and disruptive situations. These benefits will continue, and increase as technology pushes humankind's understanding of its environment even further.
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of a 200 MHz Bandwidth Located Between 6.425 and 7.250 GHz Recommendation ITU-R RS.1029 states that 200 MHz of bandwidth between 6.425 and 7.250 GHz is required for sea surface temperature and soil moisture remote sensing. Radio Regulations footnote 5.458 recognizes the current use of this frequency range for remote sensing of sea surface temperature and states, "Administrations should bear in mind the needs of the Earth exploration-satellite (passive)
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