1、 Recommendation ITU-R RS.2065-0 (12/2014) Protection of space research service space-to-Earth links in the 8 400-8 450 MHz and 8 450-8 500 MHz bands from unwanted emissions of synthetic aperture radars operating in the Earth exploration-satellite service (active) around 9 600 MHz RS Series Remote se
2、nsing systems ii Rec. ITU-R RS.2065-0 Foreword The role of the Radiocommunication Sector is to ensure the rational, equitable, efficient and economical use of the radio-frequency spectrum by all radiocommunication services, including satellite services, and carry out studies without limit of frequen
3、cy range on the basis of which Recommendations are adopted. The regulatory and policy functions of the Radiocommunication Sector are performed by World and Regional Radiocommunication Conferences and Radiocommunication Assemblies supported by Study Groups. Policy on Intellectual Property Right (IPR)
4、 ITU-R policy on IPR is described in the Common Patent Policy for ITU-T/ITU-R/ISO/IEC referenced in Annex 1 of Resolution ITU-R 1. Forms to be used for the submission of patent statements and licensing declarations by patent holders are available from http:/www.itu.int/ITU-R/go/patents/en where the
5、Guidelines for Implementation of the Common Patent Policy for ITU-T/ITU-R/ISO/IEC and the ITU-R patent information database can also be found. Series of ITU-R Recommendations (Also available online at http:/www.itu.int/publ/R-REC/en) Series Title BO Satellite delivery BR Recording for production, ar
6、chival and play-out; film for television BS Broadcasting service (sound) BT Broadcasting service (television) F Fixed service M Mobile, radiodetermination, amateur and related satellite services P Radiowave propagation RA Radio astronomy RS Remote sensing systems S Fixed-satellite service SA Space a
7、pplications and meteorology SF Frequency sharing and coordination between fixed-satellite and fixed service systems SM Spectrum management SNG Satellite news gathering TF Time signals and frequency standards emissions V Vocabulary and related subjects Note: This ITU-R Recommendation was approved in
8、English under the procedure detailed in Resolution ITU-R 1. Electronic Publication Geneva, 2015 ITU 2015 All rights reserved. No part of this publication may be reproduced, by any means whatsoever, without written permission of ITU. Rec. ITU-R RS.2065-0 1 RECOMMENDATION ITU-R RS.2065-0 Protection of
9、 space research service space-to-Earth links in the 8 400-8 450 MHz and 8 450-8 500 MHz bands from unwanted emissions of synthetic aperture radars operating in the Earth exploration-satellite service (active) around 9 600 MHz (2014) Scope This Recommendation provides mitigation techniques that can r
10、educe the unwanted emissions of Earth exploration-satellite service (EESS) (active) systems in the space research service (SRS) band and recommends that EESS (active) systems fully protect the operations of SRS (deep space) missions during their critical events and prevent damages to the SRS earth s
11、tation receivers at all times. Keywords Critical events, damages, deep space, earth stations, EESS (active), interference, mitigation, protection, criterion, receiver, SAR, saturation, space-to-Earth, space research service, SRS, synthetic aperture radar, unwanted emissions Abbreviations/Glossary EE
12、SS Earth exploration satellite service LFM Linear FM (frequency modulation) SAR Synthetic aperture radar SRS Space research service TR Transmit and receive Related ITU Recommendations, Reports Recommendation ITU-R RS.2043 Characteristics of synthetic aperture radars operating in the Earth exploratio
13、n-satellite service (active) around 9 600 MHz Recommendation ITU-R SA.609 Protection criteria for radiocommunication links for manned and unmanned near-Earth research satellites Recommendation ITU-R SA.1014 Telecommunication requirements for manned and unmanned deep-space research Recommendation ITU
14、-R SA.1157 Protection criteria for deep-space research Recommendation ITU-R SM.1541 Unwanted emissions in the out-of-band domain Report ITU-R RS.2308 Radio frequency compatibility of unwanted emissions from 9 GHz EESS synthetic aperture radars with the Earth exploration-satellite service (passive),
15、space research service (passive), space research service and radio astronomy service operating in the frequency bands 8 400-8 500 MHz and 10.6-10.7 GHz, respectively 2 Rec. ITU-R RS.2065-0 The ITU Radiocommunication Assembly, considering a) that the frequency band 9 300-9 800 MHz is allocated to EES
16、S (active) on primary basis; b) that the frequency band 9 800-9 900 MHz is allocated to EESS (active) on secondary basis; c) that the frequency band 8 400-8 450 MHz is allocated to SRS (deep space) space-to-Earth links on primary basis; d) that the frequency band 8 450-8 500 MHz is allocated to SRS
17、on primary basis for space-to-Earth links; e) that systems operating active radars in the frequency band 9 300-9 900 MHz use high power emissions in the space-to-Earth direction; f) that SRS (deep space) earth stations operating in the frequency band 8 400-8 450 MHz as described in Recommendation IT
18、U-R SA.1014, use extremely sensitive receivers; g) that these SRS earth stations also support SRS missions such as Lagrange and lunar missions in the frequency band 8 450-8 500 MHz; h) that protection criteria of the SRS (deep space) missions in the frequency band 8 400-8 450 MHz is given in Recomme
19、ndation ITU-R SA.1157 and the protection criteria of the SRS missions in the 8 450-8 500 MHz band is given in Recommendation ITU-R SA.609; i) that the unwanted emissions of EESS (active) operating in the frequency band 9 300-9 900 MHz may exceed the SRS (deep space) protection criterion in the 8 400
20、-8 450 MHz band; j) that the frequency band 8 400-8 450 MHz is used by nearly all SRS (deep space) missions for support of their routine and critical events and the frequency band 8 450-8 500 MHz is used by nearly all SRS Lagrange and lunar missions; k) that SRS (deep space) critical events such as
21、launch, orbit insertion, planetary fly-by, and entry-descend-landing, including sample return, often determine the success of deep space missions; l) that interference during the SRS (deep space) missions critical events can lead to the loss of critical data, or may even jeopardize the health and sa
22、fety of a spacecraft; m) that, during routine operations of the SRS (deep space) missions, unwanted emissions of EESS (active) exceeding the protection criterion of SRS (deep space) with a very small probability may be acceptable; n) that unwanted emissions of EESS (active) may exceed the saturation
23、 levels and the damage levels of SRS earth station receivers described in Annex 1, recommends 1 that EESS SAR systems should use the methods described in Annex 2 to reduce their unwanted emissions in the frequency band 8 400-8 500 MHz in order to: a) avoid damaging the SRS earth station receivers at
24、 all times; b) reduce the probability of saturating SRS earth station receivers; c) avoid causing interference exceeding the protection criteria of the SRS (deep space) earth stations during critical events; Rec. ITU-R RS.2065-0 3 2 that, as a last resort, if recommends 1 cannot be satisfied fully b
25、y the application of the methods described in Annex 2, operators of EESS SAR systems should predict any remaining potential interference events and mitigate them by coordinating their operations with the operators of SRS missions at least seven days before an event for EESS SAR routine operations an
26、d at least 24 hours for EESS SAR acquisition of images in cases of emergency such as disaster management; 3 that in order to facilitate the use of some of the mitigation techniques as well as operational coordination, operators of EESS SAR and SRS systems should share the orbital and telecom charact
27、eristics of their respective operations, including the up-to-date trajectory of their missions, antenna pointing, and schedule of critical events; 4 that when applying recommends 1, 2 and 3, the damage and saturation levels of Table 1 of Annex 1 should apply; 5 that recommends 1, 2, 3 and 4 should o
28、nly apply to the SRS earth stations listed in Recommendation ITU-R SA.1014. Annex 1 Damage and saturation to front end of the SRS deep-space earth station receivers The locations and characteristics of SRS deep-space receivers are described in Recommendation ITU-R SA.1014. The United States of Ameri
29、cas civil space agency, the National Aeronautics and Space Administration (NASA), and the European Space Agency (ESA) have provided characteristics of saturation and potential damage levels to their deep-space earth station receivers. These levels are summarized in the Table A1-1 below. TABLE A1-1 S
30、aturation and damage levels of SRS (deep space) earth station receivers Parameter Unit NASA ESA Frequency band MHz 8 200-8 700 8 400-8 500 Saturation level dBW 115 117 Damage level dBW 105 107 These saturation and damage levels are measured directly at the input terminal of the receiver front ends.
31、NASAs SRS deep-space earth station receivers are designed to also support NASAs solar system radar operating in the 8 500-8 700 MHz band, which is allocated to the radiolocation service. SRS earth stations as described in Recommendation ITU-R SA.1014 are designed to also support SRS missions such as
32、 Lagrange missions and lunar missions in the 8 450-8 500 MHz band. These damage levels should not be exceeded at any time. The unwanted emission from the EESS (active) should be below the saturation level during the critical events of SRS deep-space missions. SRS earth stations that are not describe
33、d in Recommendation ITU-R SA.1014 typically use different RF front-end technologies. They are typically less susceptible to saturation and damages from the unwanted emissions of EESS (active). 4 Rec. ITU-R RS.2065-0 Annex 2 Mitigation techniques for reducing unwanted emissions in the SRS in the freq
34、uency bands 8 400-8 450 MHz and 8 450-8 500 MHz from the EESS (active) systems operating around 9 600 MHz This Annex presents the computations of the theoretical unwanted emissions of EESS (active) systems around 9 600 MHz using the parameters for SAR-1, SAR-2 and SAR-3 from Recommendation ITU-R RS.
35、2043. Several mitigation techniques to reduce the unwanted emissions of EESS (active) system in the 8 400-8 450 MHz SRS deep space band and in the 8 450-8 500 MHz SRS band are discussed. 1 Protection of SRS space-to-Earth links Recommendation ITU-R SA.1157 gives the protection criterion of deep-spac
36、e research earth stations as 221 dB(W/Hz) for the SRS frequency band 8 400-8 450 MHz. The calculation of non-line-of-sight interference due to trans-horizon propagation should be based on weather statistics that apply for 0.001% of the time. Recommendation ITU-R SA.1157 provides the protection crite
37、rion for receiver systems in SRS deep-space systems. Compliance to the protection criterion for these assets determines the mission success of SRS deep-space missions. Harmful interference during mission critical events, e.g. orbit insertions, planetary fly-bys, and entry-decent-and-landing (EDL) ph
38、ases, can cause potential loss of a spacecraft or the loss of irreplaceable data. There are also critical events such as one-time scientific observations where a spacecraft penetrates the atmosphere of a planet or a moon, or it impacts a moon, a planet, an asteroid, or a comet. The spacecraft may be
39、 destroyed in the process. The data transmitted during the approach or the moments before and during the impacts define the success of the missions. Therefore, the protection of SRS deep space spacecraft and earth stations during mission critical events, to the extent demanded by Recommendation ITU-
40、R SA.1157, is crucial for the success of SRS deep-space missions. In addition, spacecraft emergencies for deep space systems should be considered as critical events. Additionally, Recommendation ITU-R SA.609 gives the protection criterion of space research earth stations as 216 dB (W/Hz) for the SRS
41、 frequency band 8 450-8 500 MHz. The calculation of interference that may result from atmospheric and precipitation effects should be based on weather statistics for 0.1% of the time for unmanned missions such as Lagrange and lunar missions. 2 Characteristics of EESS (active) systems around 9 600 MH
42、z The 9 300-9 900 MHz band, typically identified by as the 9 600 MHz EESS (active) band, is used by SAR systems. Recommendation ITU-R RS.2043 provides the characteristics of three SAR systems operating in band. Rec. ITU-R RS.2065-0 5 TABLE A2-1 Characteristics of SAR-1, SAR-2 and SAR-3 systems Param
43、eter SAR-1 SAR-2 SAR-3 Orbital altitude (km) 400 619 506 Orbital inclination (degrees) 57 98 98 RF centre frequency (GHz) 9.6 9.6 9.6 Peak radiated power (W) 1 500 5 000 25 000 Pulse modulation Linear FM chirp Linear FM chirp Linear FM chirp Chirp bandwidth (MHz) 10 400 450 Pulse duration (s) 33.8 1
44、0-80 1-10 Pulse repetition rate (pps) 1 736 2 000-4 500 410-515 Duty cycle (%) 5.9 2.0-28.0 0.04-0.5 Range compression ratio 338 12 000 450-4 500 Antenna type Slotted waveguide Planar array Planar phased array Antenna peak gain (dBi) 44.0 44.0-46.0 39.5-42.5 e.i.r.p. (dBW) 75.8 83.0 83.5-88.5 Antenn
45、a orientation from Nadir 20 to 55 34 20 to 44 Antenna beamwidth 5.5 (El) 0.14 (Az) 1.6-2.3 (El) 0.3 (Az) 1.1-2.3 (El) 1.15 (Az) Antenna polarization Linear vertical Linear HH or VV Linear horizontal/vertical System noise temperature (K) 551 500 600 3 Unwanted emission of EESS (active) systems in the
46、 frequency range 8 400-8 500 MHz The theoretical unwanted emission levels of the three SAR systems described in Table A2-1 in the frequency band 8 400-8 450 MHz are shown in Table A2-2. The linear FM (LFM) SAR systems are assumed to have 10-ns rise-time and 10-ns fall-time with trapezoidal waveforms
47、. The pulse durations for SAR-2 and SAR-3 systems are 10 s and 1 s, respectively. The SRS deep space earth station antenna gain is 74 dBi. 6 Rec. ITU-R RS.2065-0 TABLE A2-2 Unwanted emissions from SAR-1, SAR-2, and SAR-3 in the 8 400-8 450 MHz band Parameter SAR-1 SAR-2 SAR-3 e.i.r.p. (dBW) 76 83 86
48、 Bandwidth (MHz) 10 400 450 Minimum slant range (km) 424 654 536 Space loss (dB) 164 167 166 Rx antenna peak gain (dBi) 74 74 74 Polarization loss (dB) 3 3 3 Spectral roll-off (dB) 109 86 78 Rx interference PSD (dB(W/Hz) 196 185 174 Deep-space protection criterion (dB(W/Hz) 221 221 221 Exceedance of
49、 protection criterion (dB) 25 36 47 Table A2-2 shows that the unwanted emissions of SAR-1, SAR-2, and SAR-3 systems exceed the deep space protection criterion by 25-47 dB. The unwanted emissions from the SAR systems are computed based on theoretical roll-off of SAR signals. Higher unwanted emissions are possible if EESS (active) systems include components such as high-efficiency power amplifiers operating in saturation modes. Computation of unwanted emissions of the SAR systems using Annex 8 of Recommendation ITU-R SM.1541 results in higher wanted e
