Sharing between spaceborne passive sensors and the inter-satellite service operating near 118 and 183 ghz




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Rec. ITU-R SA. 1416

RECOMMENDATION ITU-R SA.1416*

SHARING BETWEEN SPACEBORNE PASSIVE SENSORS AND THE
INTER-SATELLITE SERVICE OPERATING NEAR 118 AND 183 GHz

(Question ITU-R 228/7)


(1999)

Rec. ITU-R SA. 1416

The ITU Radiocommunication Assembly,



considering

a) that Resolution 723 (WRC-97) resolves to address the allocations of frequency bands above 71 GHz to passive services;

b) that Recommendation ITU-R SA.515 indicates that the band 115-122 GHz is necessary for spaceborne passive sensing to obtain vertical temperature profiles;

c) that Recommendation ITU-R SA.515 indicates that the band 175-192 GHz is necessary for spaceborne passive sensing to obtain vertical water vapour profiles;

d) that weather forecasting is an important tool essential to all human economic activities, and also plays a predominant role in early identification and warnings of potentially dangerous phenomena;

e) that atmospheric temperature and water vapour profiles are essential data needed for weather forecasting on a global basis;

f) that the oxygen absorption band around 118 GHz and the water vapour absorption band around 183 GHz represent a unique natural resource for remote temperature and water vapour profile sensing in the atmosphere;

g) that these passive measurements are extremely vulnerable to interference because the natural variability of the atmosphere makes it impossible to recognize and to filter measurements contaminated by interference;

h) that contaminated passive sensor measurements can have a dramatic, adverse impact on climate studies and the quality of weather predictions,

recognizing

a) that the bands 116-126 GHz, 174.5-182 GHz, and 185-190 GHz are currently allocated to the inter-satellite service (ISS);

b) that Recommendation ITU-R SA.1029 provides interference criteria for the passive sensors in the bands 115 122 GHz and 175-192 GHz;

c) that studies conducted in the bands 116-122 GHz, 174.5-182 GHz and 185-190 GHz have shown that the inter-satellite links (ISLs) in a non geostationary (non-GSO) satellite system can cause interference to the passive sensors well in excess of these protection criteria (see Annex 1);

d) that studies conducted in these bands have shown that ISLs in GSO satellite systems can share the band with passive sensors with suitable restrictions on the power flux-density (pfd) produced by GSO satellites at the sensor orbital altitude (see Annex 1);

e) that No. S9.7 of the Radio Regulations of the specifies that satellite stations using the geostationary-satellite orbit must consider and coordinate with other space radiocommunication systems,



recommends

1 that, in view of recognizing b) and c), passive sensors and ISLs of non-GSO satellite systems should not operate on a co-frequency basis in the bands 116-122 GHz, 174.5-182 GHz and 185-190 GHz;

2 that, in view of recognizing d), passive sensors and ISLs of GSO satellite systems can share the 116-122 GHz band provided that the single-entry pfd at all altitudes from 0 to 1 000 km above the Earth's surface and in the vicinity of all geostationary orbital positions occupied by passive sensors, produced by a station in ISS, for all conditions and for all methods of modulation, does not exceed –148 dB(W/(m2 · 200 MHz)) for all angles of arrival;

3 that, in view of recognizing d) and e), passive sensors and ISLs of GSO satellite systems can share the 174.5 182 GHz and 185-190 GHz bands provided that the single-entry pfd at all altitudes from 0 to 1 000 km above the Earth's surface and in the vicinity of all geostationary orbital positions occupied by passive sensors, produced by a station in the ISS, for all conditions and for all methods of modulation, does not exceed –144 dB(W/(m2 · 200 MHz)) for all angles of arrival.
ANNEX 1

Feasibility of sharing between the Earth exploration-satellite service (EESS)
(spaceborne passive sensors) and the ISS operating near 118 and 183 GHz

1 Introduction


The frequency bands near 118 and 183 GHz are allocated to the EESS on a primary basis for passive sensors as shown in Table 1. The allocation near 118 GHz is shared with other services. Near 183 GHz, the passive services have an exclusively allocated band. A need has been identified in this band to expand the frequency range over which passive measurements can be made, and therefore the passive sensors may have to share with active services in adjacent bands. It is important that frequency sharing be examined:

– to determine if currently allocated sharing at 118 GHz adequately protects the passive sensors; and

– to determine if the expansion of the range over which passive sensors operate near 183 GHz would create potential sharing problem with other services.

TABLE 1


EESS allocations at 116-126 GHz and near 183 GHz

Frequency band
(GHz)

Allocation to services
(all worldwide)

116-126


EESS (PASSIVE)
FIXED
INTER-SATELLITE
MOBILE
SPACE RESEARCH (PASSIVE)

174.5-176.5



EESS (PASSIVE)
FIXED
INTER-SATELLITE
MOBILE
SPACE RESEARCH (PASSIVE)

176.5-182



FIXED
INTER-SATELLITE
MOBILE

182-185


EESS (PASSIVE)
RADIO ASTRONOMY
SPACE RESEARCH (PASSIVE)

185-190


FIXED
INTER-SATELLITE
MOBILE


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