1、 Recommendation ITU-R M.1640-1 (01/2018) Characteristics of, and protection criteria for sharing studies for radars operating in the radiodetermination service in the frequency band 33.4-36 GHz M Series Mobile, radiodetermination, amateur and related satellite services ii Rec. ITU-R M.1640-1 Forewor
2、d 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 frequency range on the basis of which Recommendation
3、s 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) ITU-R policy on IPR is described in the Comm
4、on 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 Guidelines for Implementation of the Common P
5、atent 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, archival and play-out; film for television BS B
6、roadcasting 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 applications and meteorology SF Frequency shar
7、ing 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 English under the procedure detailed in Resol
8、ution ITU-R 1. Electronic Publication Geneva, 2018 ITU 2018 All rights reserved. No part of this publication may be reproduced, by any means whatsoever, without written permission of ITU. Rec. ITU-R M.1640-1 1 RECOMMENDATION ITU-R M.1640-1 Characteristics of, and protection criteria for sharing stud
9、ies for radars operating in the radiodetermination service in the frequency band 33.4-36 GHz (Questions ITU-R 213/7 and ITU-R 226/8) (2003-2018) Scope This Recommendation provides the technical characteristics and protection criteria for the radiodetermination systems operating in the band 33.4-36 G
10、Hz. The text was developed as a resource document intended to support sharing studies where sharing between the radiodetermination service and other services may be possible. Keywords Characteristics, protection criteria, radar, radiometric imagers, metric radar, seeker, search radar, track radar Ab
11、breviations/Glossary IF: Intermediate frequency RF: Radio frequency RR: Radio regulations Rx: Receive Tx: Transmit Related ITU Recommendations and Reports Recommendation ITU-R M.1461 Procedures for determining the potential for interference between radars operating in the radiodetermination service
12、and systems in other services The ITU Radiocommunication Assembly, considering a) the antenna, signal 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 radi
13、odetermination radars are determined by the mission of the system and vary widely even within a band; c) that representative technical and operational characteristics of radars are required to determine the feasibility of introducing new types of systems into frequency bands; d) that procedures and
14、methodologies to analyse compatibility between radars and systems in other services are provided in Recommendation ITU-R M.1461; e) that radiodetermination radars operate in the frequency band 33.4-36 GHz; f) that the frequency band 33.4-34.2 GHz is allocated to the radiolocation service on a primar
15、y basis; 2 Rec. ITU-R M.1640-1 g) that the frequency band 34.2-34.7 GHz is allocated to the radiolocation and space research (deep space) (Earth-to-space) services on a primary basis; h) that the frequency band 34.7-35.2 GHz is allocated to the radiolocation service on a primary basis and to space r
16、esearch service on a secondary basis; i) that the frequency band 35.2-35.5 GHz is allocated to the meteorological aids and radiolocation services on a primary basis; j) that the frequency band 35.5-36 GHz is allocated to the meteorological aids, Earth exploration-satellite (active), radiolocation, a
17、nd space research (active) services on a primary basis, recommends 1 that the technical and operational characteristics of the radiodetermination radars described in Annex 1 should be considered representative of those operating in the frequency band 33.4-36 GHz; 2 that in the case of continuous (no
18、n-pulsed) interference, an interfering signal power to radar receiver noise power level, I/N, of 6 dB should be used as the required protection level for radiolocation systems for sharing studies in general, including search and track radar (F) in Table 1 of Annex 1 in the frequency range 33.4-36 GH
19、z; 3 that for studies of sharing the band 33.4-36 GHz between radars (A-E) in Table 1 of Annex 1 and systems in other services, the following criteria be used: that for radiometric imagers the short-term protection criteria should be 137.8 dB(W/2 GHz) for not longer than 3 s, and the long-term prote
20、ction criteria should be no more than 144.8 dB(W/2 GHz) for not longer than 60 s; that for metric radars and seekers the short-term protection criteria should be 126.2 dB(W/6 MHz) for not longer than 5 s, and the long-term protection criteria should be no more than 136.1 dB(W/6 MHz) for not longer t
21、han 60 s. Annex 1 Characteristics of, and protection criteria for radars operating in the radiodetermination service in the frequency band 33.4-36 GHz 1 Purpose The characteristics and protection criteria in this Recommendation have been provided for use in sharing studies called for under Resolutio
22、ns 712 (WRC-2000) and 730 (WRC-2000) and to assess the compatibility between the radars and other systems operating in the frequency band 33.4-36 GHz. 2 Technical characteristics Frequencies around 35 GHz and 94 GHz, correspond roughly to the first two propagation windows in the atmospheric absorpti
23、on characteristics of the millimetre wave spectrum, and use of these frequencies is required by systems in the radiodetermination service in order to achieve the high measurement accuracy and target resolution possible at millimetre wavelength. Both passive and active sensors operating in the radiod
24、etermination service around these frequencies are used for mapping, target identification, navigation, aim-point determination, test range instrumentation, etc. Rec. ITU-R M.1640-1 3 Table 1 summarizes technical characteristics of representative systems deployed in these bands. This information is s
25、ufficient for general calculation to assess the compatibility between these radars and other systems. TABLE 1 Technical characteristics of radars around 35 GHz Parameter Units Radar A Radar B Radar C Radar D Radar E Radar F Use Imaging Imaging Metric Metric Seeker Search and track Sensor type Passiv
26、e Active Active Active Active Active Modulation Pulse Pulse Pulse Linear FM Linear FM Pulse Compression ratio 200 50 Pulse width s 0.05 0.25 0.05 10 20 Tx peak power kW 0.5 135 1 0.001 10 Pulse repetition frequency kHz 30 1 50 10 10-30 RF bandwidth MHz 80 10 101 12 2000 Antenna gain dBi 35 30 52 51
27、28.7 52 Beamwidth degrees 0.5 3.0 0.75 10 0.25 0.25 0.5 0.5 4.4 4.4 0.25 0.25 Rx IF bandwidth GHz 2 0.040 0.006 0.185 0.100 0.006 Noise temperature K 850 Noise figure dB 4.5 10 10 5 4 Rx sensitivity dBm 81 95 78 93 Tuning Fixed Fixed Fixed Frequency hop Fixed Frequency hopping 3 Protection criteria
28、Short-term interference criteria are developed in the following paragraphs for the terrestrial radiolocation systems given in Table 1. 3.1 Radiometric imagers Assuming negligible system gain variation, the minimum temperature sensitivity, T of a radiometric imaging system is: irA tBTTT (1) where: TA
29、: antenna noise temperature Tr: receiver noise temperature B: RF bandwidth ti: integration time. 4 Rec. ITU-R M.1640-1 The radiometer threshold, P is given by: P = k T B (2) where k is Boltzmans constant = 1.38 1023, and T and B are as given above. Using equations (1) and (2), we find that a radiome
30、ter with a 2 GHz bandwidth, 850 K system noise temperature and a 1 ms integration time has P = 137.8 dB(W/2 GHz). Short-term protection criterion Given that it is an unlikely event, an operator can accept a severely degraded image for several seconds. Permitting the unwanted signal level to approach
31、 the radiometers threshold results in an allowed unwanted signal level of 137.8 dB(W/2 GHz) for no more than 3 s. Long-term protection criterion A lesser degradation may be considered for time periods lasting up to 1 min. In this case the degradation is not necessarily readily evident to an operator
32、, but does cause some loss in image resolution. Permitting the unwanted signal to reach 20% of the radiometers threshold yields an allowed interference level of 144.8 dB(W/2 GHz) for no more than 60 s. 3.2 Metric radars and seekers For the case of terrestrial metric (instrumentation) radars and the
33、seekers, it can be noted that two important performance parameters, angular accuracy and target detection range R, are related to the received S/N by: NS/1 (3) R 4 /1NS(4) Narrow antenna beamwidth and high angular accuracy are possible with fairly small antenna sizes at millimetre wavelengths. This
34、characteristic, in fact, is a major reason why missile seekers and instrumentation radars have been developed at these frequencies. From equations (3) and (4) it can be seen that the angular accuracy of the radar is more sensitive to the received S/N than is the detection range so this performance p
35、arameter will be used to determine allowed interference levels1. As in the case of the imaging system in the previous section, short term and long-term criteria can be established for allowed degradation in system performance due to unwanted signals (interference). Short-term interference is allowed
36、 to significantly degrade the system for a period of time short enough that it may be acceptable to the operator, given that it is an unlikely event. Long-term interference is allowed to incrementally degrade system performance to an extent not readily apparent to the operator, but is otherwise acce
37、ptable for the specified duration of time. Short-term protection criterion A degradation in the radar S/N will cause a tracking error, which can partially negate the advantage of operating at higher frequencies, and may significantly affect the radars mission. Permitting an unwanted signal to reach
38、the radar noise level (I/N = 0 dB) will result in a 40% increase in the angle error. It can be again assumed that this degradation is not overly important given that it is 1 It is assumed here, for simplicity, that interfering signals will be interpreted by the victim receiver as an increase in the
39、noise power in the IF stages. The actual response by radar systems may need to be considered, but is beyond the scope of this generalized treatment. Rec. ITU-R M.1640-1 5 an unlikely event for periods of time less than about 5 s. The allowed unwanted signal level can then be as great as 126.2 dB(W/6
40、 MHz) for no more than 5 s (using the radar with the narrowest bandwidth given in Table 1). Long-term protection criterion It would seem reasonable that the radar error becomes more important over increasingly longer periods of time. For periods up to 1 min in duration it should be assumed that an i
41、ncrease in the angle error, due to an unwanted signal, should not exceed 5%. The long-term criterion is then an allowed unwanted signal level of 136.1 dB(W/6 MHz) for no more than 60 s. 3.3 Search and track radars For search and track radars, the protection criteria of an interfering signal power to radar receiver noise power level, I/N, is 6 dB.
