Views of the U.S. NAS and NAE on Agenda Items at the World Radiocommunication Conference 2015 (2013) / Chapter Skim
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2 Views on WRC-15 Agenda Items
2 Views on WRC-15 Agenda Items
Pages 9-30
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2 Views on WRC-15 Agenda Items The following pages discuss the committee's consensus on the potential impact and relevance of certain agenda items at issue at the upcoming World Radiocommunication Conference (WRC)
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Radio Astronomy Service Several bands in the subject frequency range are allocated on a primary basis to RAS, including 406-410 MHz, 1400-1427 MHz, 1610.6-1613.8 MHz, 2690-2700 MHz and 4990-5000 MHz. These bands are widely used in RAS applications and care must be taken not to interfere with established observatories using these frequencies.
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From page 11... ...
: sea surface salinity, soil moisture, sea surface temperature, vegetation index 1400-1427 P RAS: galactic and extragalactic HI, source spectra, interstellar medium, recombination lines, galactic continuum EESS (passive) : soil moisture, sea surface salinity, sea surface winds 1525-1535 S EESS RAS: extragalactic hydroxyl (OH)
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Passive EESS users below 6 GHz include several satellite facilities, which deliver science and operational data for climate science and weather forecasting. These include the European Soil Moisture and Ocean Salinity (SMOS)
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In addition to the protected bands shared with RAS, EESS uses several active bands in the subject frequency range. The 1215-1300 MHz band is used for Earth surface characterization by the Aquarius and SMAP missions.
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when making any new allocations to International Mobile Telecommunications (IMT)
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Radio Astronomy Service The 380-470 MHz band mentioned in the resolution contains a primary allocation for radio astronomy at 406.1-410 MHz, which is an important band for interstellar medium studies, pulsars, and baryonic acoustic oscillations. The mentioned band 4940-4990 MHz is adjacent to the RAS primary allocation at 4990-5000 MHz, which is an important allocation for very long baseline interferometry.
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Spectral line observations in this frequency range include the formaldehyde transition at 14.4885 GHz (rest frequency) and Doppler shifted carbon monoxide from distant galaxies.1 Of significant concern for RAS would be modifications of the current allocations for FSS at 14.47-14.5 GHz, which are currently Earth-to-space.
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From page 17... ...
Observations in both the passive and active bands are used for a number of applications including observations of soil moisture, sea surface temperatures, sea surface height, ocean winds, sea ice, snow, and precipitation. These observations are critically important to predict weather, monitor climate, quantify changes in global water cycle, monitor and predict agricultural productivity and to better understand linkages and feedback in ocean circulation and climate change.
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From page 18... ...
; and the possibility of allocating the bands 73757750 MHz and 8025-8400 MHz to the maritime-mobile satellite service and additional regulatory measures, depending on the results of appropriate studies [Agenda Item 1.9.2] ." The 7000-8500 MHz band includes primary allocations to Fixed Service (FS)
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Specifically, the current allocation of 8400-8500 MHz to SRS has allowed RAS to use this band, without formal protection, since there are relatively few deep space missions, and the signals they send back to Earth are very faint compared to typical satellite downlinks. New allocations to FSS at these frequencies would be particularly deleterious to RAS because satellites are difficult to avoid: They appear at high elevations, can cross much of the sky, and therefore enter into the line of sight of radio telescopes conducting astronomical observations.
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The committee does not oppose the proposed Maritime Mobile-Satellite Service allocations 7375-7750 MHz (s-E)
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." A principal concern is the 22.21-22.5 GHz band, which has a coprimary allocation between the EESS and RAS passive services and the fixed and mobile services, except for aeronautical and mobile services, and the 23.6-24 GHz band, which has primary allocation for EESS passive services. In the frequency range 22-26 GHz, there are primary allocations for RAS at 22.21-22.5 GHz and 23.6-24 GHz and footnote protection at 22.01-22.5 GHz, 22.81-22.86 GHz, and 23.0723.12 GHz (Footnotes 5.149 and US 342)
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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 was unusable due to RFI contamination.2 Recommendation: The committee recommends that any new Mobile-Satellite Service allocations strictly adhere to all current regulation requirements for unwanted emission and out-of-band emission in the protected scientific service bands, which includes a critical tracer of water vapor in the atmosphere. 1 The Doppler shift associated with the expansion of the universe is characterized by the parameter z (known as redshift)
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scientific programs with little deleterious impact on Radio Astronomy Service or EESS (passive) , the committee supports Agenda Item 1.11.
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ITU Footnote 5.340 says "All emissions are prohibited in the 10.68-10.7 GHz band except those provided for by No. 5.483." This protected band is critical for measurement of parameters such as sea surface winds, soil moisture, and precipitation.
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Recommendation: The committee recommends that any new Automatic Identification System (AIS) allocations avoid the bands allocated to the passive scientific services and strictly adhere to all current regulation requirements for unwanted emission and out-of-band emission in the protected scientific service bands.
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." This agenda item does not indicate the specific frequency range of interest, but the desired allocation would come from existing Aeronautical Mobile Service (AeMS) , Aeronautical Mobile (R)
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The choice of frequency depends on the Earth/ocean surface interaction with the electromagnetic field and therefore cannot be chosen arbitrarily. Dual frequency operation allows ionospheric delay compensation for adequate accuracy of measurements.
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Radio Astronomy Service The primary concern for radio astronomy is the operation of radars close to millimeter-wave radio observatories. Based on tests of a SRR conducted at the University of Arizona's 12 meter mmwave telescope located at Kitt Peak, Arizona, an exclusion zone in the ~30-40 km range around a mm-wave observatory would be required to keep interference from a single vehicle below the Recommendation ITU-R RA.769-2 level of -148 dBW/m2/MHz.2 While smaller radii might suffice in areas without direct line of sight to the radio telescope, aggregate effects should be taken into account as more vehicles are outfitted with SRR in the coming years.
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The committee feels strongly that, at a minimum, the driver of a vehicle should be allowed to take personal responsibility for turning off the radar, with appropriate warnings to ensure safety, within an exclusion zone around a mm-wave observatory in the same manner as a switch allows vehicle headlights to be turned off when approaching an optical observatory at night. Alternatively, the radar could be automatically disabled by a geolocation device.
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From page 30... ...
WRC-12) Agenda Item 2 reads as follows: "to examine the revised ITU-R Recommendations incorporated by reference in the Radio Regulations communicated by the Radiocommunication Assembly, in accordance with Resolution 28 (Rev.WRC-03)
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