1、 Recommendation ITU-R M.1466-1 (01/2017) Characteristics of and protection criteria for radars operating in the radionavigation service in the frequency band 31.8-33.4 GHz M Series Mobile, radiodetermination, amateur and related satellite services ii Rec. ITU-R M.1466-1 Foreword The role of the Radi
2、ocommunication 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 frequency range on the basis of which Recommendations are adopted. The reg
3、ulatory 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) ITU-R policy on IPR is described in the Common Patent Policy for I
4、TU-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 Guidelines for Implementation of the Common Patent Policy for ITU-T
5、/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, archival and play-out; film for television BS Broadcasting service (s
6、ound) 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 applications and meteorology SF Frequency sharing and coordination b
7、etween 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 English under the procedure detailed in Resolution ITU-R 1. Electro
8、nic Publication Geneva, 2017 ITU 2017 All rights reserved. No part of this publication may be reproduced, by any means whatsoever, without written permission of ITU. Rec. ITU-R M.1466-1 1 RECOMMENDATION ITU-R M.1466-1* Characteristics of and protection criteria for radars operating in the radionavig
9、ation service in the frequency band 31.8-33.4 GHz (2000-2017) Scope This Recommendation specifies the characteristics of and protection criteria for radars operating in the radionavigation service in the frequency band 31.8-33.4 GHz. These technical and operational characteristics are to be used as
10、a guideline in analyzing compatibility between radars operating in the radiodetermination service with systems in other services. Keywords Radionavigation, aircraft Abbreviations/Glossary dBi Antenna gain relative to an isotropic radiator dBm Power expressed in decibels relative to one milliwatt dBW
11、 Power expressed in decibels relative to one watt IF Intermediate frequency I/N Interference to receiver noise ratio PPS Pulses per second PRF Pulse repetition frequency RF Radio Frequency Related ITU-R Recommendations 1 Recommendation ITU-R M.1461 Procedures for determining the potential for interf
12、erence between radars operating in the radiodetermination service and systems in other services 2 Recommendation ITU-R M.1851 Mathematical models for radiodetermination radar systems antenna patterns for use in interference analyses The ITU Radiocommunication Assembly, considering a) that antenna, s
13、ignal propagation, target detection, and large necessary bandwidth characteristics of radar to achieve their functions are optimum in certain frequency bands; b) that the technical characteristics of radars operating in the radiodetermination service are determined by the mission of the system and v
14、ary widely even within a band; c) that the radionavigation service is a safety service as specified by RR No. 4.10 and harmful interference to it cannot be accepted; * Radiocommunication Study Group 5 made editorial amendments to this Recommendation in 2008 in accordance with Resolution ITU-R 44. 2
15、Rec. ITU-R M.1466-1 d) that considerable radiolocation and radionavigation spectrum allocations (amounting to about 1 GHz) have been removed or downgraded since WARC-79; e) that some ITU-R technical groups are considering the potential for the introduction of new types of systems (e.g. fixed wireles
16、s access and high density fixed and mobile systems) or services in bands between 420 MHz and 34 GHz used by radars in the radiodetermination service; f) that representative technical and operational characteristics of systems operating in bands allocated to the radiodetermination service are require
17、d to determine the feasibility of introducing new types of systems; g) that procedures and methodologies are needed to analyse compatibility between radars operating in the radiodetermination service and systems in other services; h) that WRC-97 requested that the ITU-R conduct studies to determine
18、what criteria would be necessary for sharing between stations in the fixed service and stations in the other services to which the frequency band 31.8-33.4 GHz is allocated; j) that the frequency band 31.8-33.4 GHz is allocated on a primary basis to the fixed and radionavigation services and that po
19、rtions of the band are allocated on a primary basis to the space research (deep space) and inter-satellite services, recommends 1 that the technical and operational characteristics of the radars operating in the radionavigation service described in Annex 1 should be considered representative of thos
20、e operating in the frequency band 31.8-33.4 GHz; 2 that Recommendation ITU-R M.1461 should be used as a guideline in analysing compatibility between radars operating in the radiodetermination service with systems in other services; 3 that the criterion of interfering signal power to radar receiver n
21、oise power level, I/N, of 6 dB should be used as the required protection level for the radionavigation radars, and that this represents the net protection level if multiple interferers are present. Annex 1 Technical and operational characteristics of radars operating in the radionavigation service i
22、n the frequency band 31.8-33.4 GHz 1 Introduction The radionavigation service operates worldwide on a primary basis in the frequency band 31.8-33.4 GHz. This Annex presents the technical and operational characteristics of representative radars operating in the radionavigation service in this frequen
23、cy band. 2 Technical characteristics of radionavigation systems in the frequency band 31.8-33.4 GHz The technical parameters of three radionavigation radars operating in the frequency band 31.8-33.4 GHz are presented in Table 1 and Table 2. All systems are operated worldwide aboard Rec. ITU-R M.1466
24、-1 3 aircraft. The radars are used for ground mapping, weather avoidance, to calibrate aircraft on-board navigation systems for accurate aerial delivery in adverse weather conditions and to provide data to pilots in order to reduce the decision height during landing phases in adverse weather conditi
25、ons. TABLE 1 Radionavigation radar characteristics in the frequency band 31.8-33.4 GHz (Radars Nos 1 and 2) Parameter Units Radar No. 1 Radar No. 2 Tuning type Fixed frequency Tunes continuously across 31.8-33.4 GHz Fixed frequency or frequency hopping Operates in either mode on one of 9 discrete ch
26、annels spaced 100 MHz apart (32.2-33 GHz) Emission type Unmodulated pulses RF emission bandwidth MHz 37 17 (instantaneous) 117 (hopping) Pulse duration s 0.2 Pulse repetition frequency pps 2 000 1 600 Peak transmitter power kW 60 39 Receiver IF bandwidth (20 dB) MHz 40 17 Receiver noise figure dB 11
27、 Antenna type Parabolic reflector Antenna main beam gain dBi 44 41.1 Antenna scan Elevation: 30 to 10, manual azimuth: 360 at 7, 12, or 21 rpm Elevation: 30 to 10, manual azimuth: 360 at 12 or 45 rpm TABLE 2 Radionavigation radar characteristics in the frequency band 31.8-33.4 GHz (Radars No. 3) Par
28、ameter Units Radar No. 3 Type Aircraft Altitude m Maximum: from 300 to ground Nominal: from 150 to ground Center frequency GHz Adjustable from 31.8 to 33.4 GHz Modulation FMCW Chirp RF emission bandwidth MHz From 20 to 500 Nominal: 200 Peak transmitter power W 5-20 Nominal 5 Pulse repetition frequen
29、cy pps 500 (FM cycle repetition frequency) Receiver IF bandwidth (3 dB) MHz 60 Receiver noise figure dB 6 4 Rec. ITU-R M.1466-1 TABLE 2 (continued) Parameter Units Radar No. 3 Sensitivity dBm 110 Input power threshold receiver overload dBm 40 Antenna type linear array Maximum antenna gain dBi 30 Ove
30、rall antenna coverage Elevation: 30 to + azimuth: 30 to +30 M - 0. 1 4 6 6 T a b l - 2 -0 1 3 0 A n te n n ab o r e s ig h t r e la tiv eto a ir c r a f t a x isE lev at ion: 30 to + 5azi mu th: 30 to + 30Instantaneous antenna azimuth gain mask pattern M - 0. 1 4 6 6 T a b l - 2 - 0 2A zi m u th an
31、g le rel at iv e to an ten n a b o res ig h t (d eg ree s )Antennagain(dBi)90 5070 30 1010 30 50 70 90A n ten n a g ai n in azi m u th505101520253035And with a zoom for azimuth angles from10 to 10 M - 0. 1 4 6 6 T a b l - 2 - 0 3A zi m u th an g le rel at iv e to an ten n a b o res ig h t (d eg ree
32、s )Antennagain(dBi)10 5 0 5 10A n ten n a g ai n in azi m u th505101520253035Rec. ITU-R M.1466-1 5 TABLE 2 (end) Parameter Units Radar No. 3 Instantaneous antenna elevation gain mask pattern M - 0. 1 4 6 6 T a b l - 2 - 0 4A zi m u th an g le rel at iv e to h o ri zo n (d eg ree s )Antennagain(dBi)8
33、0 50 20A n ten n a g ai n in el ev at io n50510152025303570 60 40 1002030 103 Operational characteristics of radionavigation systems in the frequency band 31.8-33.4 GHz Aircraft radionavigation radars operating in the frequency band 31.8-33.4 GHz have two modes of operation. The first operate contin
34、uously during flight and the second operate only during approach on airports. Mode 1: This mode encompasses an altitude range of from just off the ground to approximately 30 000 feet (9 000 m). Flight times can be up to six hours, and typically the majority of the time is spent en route, but some li
35、nger time at either the departure or destination points is expected. Up to 18 aircraft operating these radionavigation radars can be active in a small geographic area (i.e. separated by less than a kilometre from each other), though most often only 1-3 aircraft will be operating simultaneously toget
36、her. Mode 2: The second mode encompasses an altitude range of from just off the ground to below 500 feet (150 m) nominally and a maximum at 1 000 feet (300 m). Flight times depend on the time spent on approach. For nominal use only one aircraft is using the radar on the same airport but in some case
37、s, it could be considered two aircraft on the approach using such radars. 4 Protection criteria The desensitizing effect on radars from other services of a continuous-wave or noise-like type modulation is predictably related to its intensity. In any azimuth sectors in which such interference arrives
38、, its power spectral density can, to within a reasonable approximation, simply be added to the power spectral density of the radar receiver thermal noise. If power spectral density of radar-receiver noise in the absence of interference is denoted by N0 and that of noise-like interference by I0, the
39、resultant effective noise power spectral density becomes simply I0 N0. An increase of about 1 dB would constitute significant degradation, equivalent to a detection-range reduction of about 6%. Such an increase corresponds to an (I N)/N ratio of 1.26, or an I/N ratio of about 6 dB. This represents t
40、he aggregate effect of multiple interferers, when present; the tolerable I/N ratio for an individual interferer depends on the number of interferers and their geometry, and needs to be assessed in the course of analysis of a given scenario. If continuous-wave interference were received from most azi
41、muth directions, a lower I/N ratio would need to be maintained. The aggregation factor can be very substantial in the case of certain communication systems in which a great number of stations can be deployed. The effect of pulsed interference is more difficult to quantify and is strongly dependent o
42、n receivers/processor design and mode of operation. In particular, the differential processing gains for 6 Rec. ITU-R M.1466-1 valid-target return, which is synchronously pulsed, and interference pulses, which are usually asynchronous, often have important effects on the impact of given levels of pu
43、lsed interference. Several different forms of performance degradation can be inflicted by such desensitization. Assessing it will be an objective for analyses of interactions between specific radar types. In general, numerous features of radiodetermination radars can be expected to help suppress low-duty cycle pulsed interference, especially from a few isolated sources. Techniques for suppression of low-duty cycle pulsed interference are contained in Recommendation ITU-R M.1372.
