1、 Recommendation ITU-R M.1874-1(02/2013)Technical and operational characteristicsof oceanographic radars operating in sub-bands within the frequency range 3-50 MHzM SeriesMobile, radiodetermination, amateurand related satellite servicesii Rec. ITU-R M.1874-1 Foreword The role of the Radiocommunicatio
2、n 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 regulatory and p
3、olicy 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 ITU-T/ITU-R/IS
4、O/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/ITU-R/ISO/IE
5、C 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 (sound) BT Broa
6、dcasting 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 between fixed-
7、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. Electronic Publicati
8、on Geneva, 2013 ITU 2013 All rights reserved. No part of this publication may be reproduced, by any means whatsoever, without written permission of ITU. Rec. ITU-R M.1874-1 1 RECOMMENDATION ITU-R M.1874-1 Technical and operational characteristics of oceanographic radars operating in sub-bands within
9、 the frequency range 3-50 MHz (Question ITU-R 240/5) (2009-2010-2013) Scope This Recommendation provides technical and operational characteristics of oceanographic radars for use in sharing and compatibility studies and spectrum planning and systems deployment within the 3 to 50 MHz band. It provide
10、s the relevant characteristics of short-range, standard range, long-range, very-long range and high-resolution oceanographic measurement systems. The ITU Radiocommunication Assembly, considering a) that there is a need to operate oceanographic radar systems in the radiodetermination1service, using s
11、pectrum in the 3 to 50 MHz frequency range; b) that WRC-12 allocated a number of frequency bands between 3 and 50 MHz for operation of these radars; c) there is global interest in deploying operational systems on a worldwide basis; d) that performance, functions and data requirements normally determ
12、ine the range of spectrum that can be used by ocean observing radar systems, recognizing that representative technical and operational characteristics of oceanographic radar systems are required for spectrum management and deployment planning, recommends 1 that the technical and operational aspects
13、of oceanographic radars contained in the Annex should be considered when conducting sharing and compatibility studies with systems in other services; 2 that the technical and operational aspects of oceanographic radars contained in the Annex should also be taken into consideration for planning purpo
14、ses. 1The radiolocation and radionavigation services are sub-services of the radiodetermination service. 2 Rec. ITU-R M.1874-1 Annex Technical and operational characteristics of oceanographic radars operating in sub-bands within the frequency range 3-50 MHz 1 Introduction A significant percentage of
15、 the worlds population lives within 50 miles of the coastline heightening the need for accurate, reliable and detailed measurements of coastal environmental variables. Just as the winds in the atmosphere provide information about where and when weather systems occur, ocean currents determine the mov
16、ement of oceanic events. These two dynamic flows are used to determine where pollutants, man-made or natural, will travel. Presently, ocean current measurements are not as readily available as winds. Because of this, there is an increasing interest in the ability to accurately measure the currents a
17、nd waves in coastal waters. Radar systems operating at frequencies higher than 50 MHz are limited in their ability to provide data meeting current range, accuracy and resolution requirements. The global oceanography community is planning for the implementation of coastal sea surface monitoring radar
18、 networks. The benefits to society for improved measurement of coastal currents and sea state include a better understanding of issues like coastal pollution, fisheries management, search and rescue, beach erosion, maritime navigation, sediment transport and tsunami and associated surface wave reson
19、ance response (see the Appendix). Coastal radar measurements of the sea surface provide support to meteorological operations through the collection of sea state and dominant ocean wave data. In addition, oceanographic radar technology has applications in global maritime domain awareness by allowing
20、the long range sensing of surface vessels. This will benefit the global safety and security of shipping and ports2. The need for additional data to mitigate the effects of disasters, including tsunamis, to understand climate change, and to ensure safe maritime travel has led to the consideration of
21、operational use of oceanographic radar networks on a global basis. Implementation of these systems in Japan is shown in Figs 1 and 2. 2 Use of Coastal Ocean Dynamics Application Radar (CODAR) Technology in the United States of America Coast Guard Search and Rescue Planning, David Ullman; James ODonn
22、ell; Christopher Edwards; Todd Fake; David Morschauser; Coast Guard Research and Development Center Groton CT. Rec. ITU-R M.1874-1 3 FIGURE 1 An example of the observed surface current by oceanographic radars in the Tokyo Bay Watch System operated by Ministry of Land, Infrastructure, Transport and T
23、ourism, Japan M.1874-01FIGURE 2 Oceanographic radars in Japan (observation areas are shown for each fixed radar site) M.1874-02Soya warm currentOyashio currentTsushima warm currentKuroshio current4 Rec. ITU-R M.1874-1 As of 2009, 143 oceanographic radars spread unevenly throughout the United States
24、of America coastal regions (this total includes radars that are not currently operating on a regular basis). Nearly all of the oceanographic radar systems in the United States of America are owned and operated by university research departments. Existing and proposed oceanographic radar sites for th
25、e United States of America, the Pacific Islands and the Caribbean Regions are shown in Fig. 3. FIGURE 3 Existing and proposed oceanographic radar sites for the United States of America, the Pacific Islands and the Caribbean Regions M.1874-03Very high resStandard high resStandard rangeLong rangePropo
26、sedHawaii(18 proposed)American Samoa(5 proposed)Guam(3 proposed)The establishment of a network of oceanographic radar monitoring sites is included in the integrated ocean observing system (IOOS) Development Plan and is part of the global ocean observing system (GOOS) which, in turn, is a substantial
27、 component of the global Earth observing system of systems (GEOSS). Rec. ITU-R M.1874-1 5 2 Principle of operation In oceanographic radars using Bragg scattering3, the frequency range of 3 to 50 MHz (wavelength of 100 to 6 m) is very useful in measuring ocean waves driven by wind (see Fig. 4). Spati
28、al resolution of the radar is limited by the bandwidth of the signal e.g. the bandwidths of 100 and 300 kHz give resolutions of 1.5 km and 500 m, respectively4. FIGURE 4 Schematic image of radio wave propagation and a Bragg scattering M.1874-04Transmittedradiowaver: Wave length of radio waveo: Wave
29、length of oceanic waveScatteredradiowavero= r2The objectives of these systems are to: obtain continuous, real-time information for environmental operation (e.g. pollution collection and control), provide disaster-mitigation services (e.g. tsunami wave detection), provide maritime-safety services (e.
30、g. oceanic-current monitoring sea state observation) by oceanographic radars. The physical parameters that are measured by oceanographic radars and associated performance requirements dictate the frequency ranges that will support data collection. Oceanographic radars for ocean observing utilize the
31、 rough surface of the ocean to measure ocean currents and sea state. When the wave spacing on the ocean surface is equal to the half wavelength of the frequency used by the oceanographic radar, a strong signal is reflected back in the direction of the radar. This is the phenomenon known as Bragg sca
32、ttering. The frequency range 3 to 50 MHz is very useful for oceanographic observing radar operations since ocean waves are always present where the wave spacing matches the radars operational frequency. The higher temporal resolution is to be pursued for disaster-mitigation purposes while the higher
33、 spatial resolution is to be pursued for environmental operation. In addition, measurement of Doppler shift of the signal returns allows operators to measure other properties of sea state and currents. The two main transmission techniques which are used in oceanographic radars are CW pulses and line
34、ar FMCW chirps. Table 1 is a list of the parameters which are associated with a typical oceanographic radar. 3When the transmitted surface wavelength is equal to the half-wavelength of the surface wave in the Ocean, a strong reflected signal will be reflected back in the direction of the radar. 4Res
35、olution L, speed of light c (= 300 000 km/s) and bandwidth fc has relation of fc = c/2L. 6 Rec. ITU-R M.1874-1 TABLE 1 List of parameters of typical oceanographic radar waveforms Centre frequency (MHz) Sweep bandwidth (kHz) Sweep time (Tsweep) (s) Pulse period (Tpulse period) (s) Duty cycle (%) 4.53
36、 25.6 1 1 946 50 13.46 49.4 0.5 669 5024.65 101 0.5 486 50 Figure 5 illustrates the waveform structure of typical oceanographic radars. The waveform at the top of the picture represents an FMCW signal. The waveform on the bottom is representative of a gated signal. FIGURE 5 Typical oceanographic wav
37、eform structures M.1874-05Transmitted signal without pulsingTransmitted signal after pulsingTimeTimeTsweepTpulse period3 Oceanographic radar antennas A variety of antenna types are currently used with oceanographic ocean observing radar systems. Some systems utilize either a 3-element Yagi antenna o
38、r phased-array system to sweep in the azimuthal direction using multiple sets of Yagi antenna for transmission, limiting the geography over which the oceanographic radar signal is propagated. Figures 6, 7 and 8 illustrate some typical oceanographic radar antenna patterns. Rec. ITU-R M.1874-1 7 FIGUR
39、E 6 Typical oceanographic radar antenna patterns (4 vertical monopole array) M.1874-060 dB10 dB20 dB30 dB40 dBFIGURE 7 Typical oceanographic radar antenna patterns (omnidirectional; left: azimuthal, right: vertical) M.1874-07Azimuthal pattern Vertical patternRelative gain (dB)0369121518212427303333
40、30 27 24 21 18 15 12 9 6 3 020406080306003303002702402101801501209015 600 dB8 Rec. ITU-R M.1874-1 FIGURE 8 Typical oceanographic radar antenna patterns (directional, 3 elements Yagi; left: azimuthal, right: vertical) M.1874-080369121518212427303333 30 2724 21 18 15 12 9 6 3 0204060801209060300330300
41、270240210180150615Azimuthal pattern at elevation: 15.0 Vertical pattern at azimuth: 0.00 dBRelative gain (dB)4 Transmitter emissions Figures 9 and 10 illustrate typical 4.5 MHz and 24 MHz oceanographic radar emissions. FIGURE 9 4.5 MHz oceanographic radar emission M.1874-09Frequency (MHz)3.5 4.0 4.5
42、 5.0 5.59080706050403020100Powerrelativetomeasuredmaximumin 3kHz(dB)F4R15 epRec. ITU-R M.1874-1 9 FIGURE 10 24 MHz oceanographic radar emission M.1874-108023.5 24.0 24.5 25.0 25.5 26.0 26.5706050403020100F5R23.dat5 System characteristics Tables 2 through 4 contain a summary of RF characteristics for
43、 representative oceanographic radar systems for ocean monitoring at frequency ranges within 3 to 50 MHz. 10 Rec. ITU-R M.1874-1 TABLE 2 Characteristics of generic oceanographic radars for ocean observing using frequency modulated interrupted continuous wave (FMICW) Characteristics Units System 1 5 M
44、Hz System 2 13 MHz System 3 25 MHz System 4 42 MHz Function Long-range oceanographic measurements Standard oceanographic measurements High-resolution oceanographic measurements Maximum operational (measurement) range(1)km 170-200 (average during daytime)(2)60-90 (average during daytime)(2)30-50 (ave
45、rage during daytime)(2)15-25 (average during daytime)(2)Range of user selectable range resolution km 3-12(3)2-3(3)0.3-2(3)0.3-1(3)Typical sweep bandwidth kHz 25(3)50(3)100(3)125(3)Frequency range(4)MHz 4-6(4)12-14(4)24-27(4)40-44(4)Typical peak power used Maximum system capability Peak power into an
46、tenna W 50 80 50 80(100) Pulse widths s 1 000-2 000 300-600 30-100 Maximum duty cycle % 50 Pulse rise/fall time s 16/32 16 8/16Transmitter tuning method Digital Receiver tuning method Digital Output device Gated FET (Class AB operation) Transmitter stability ppm 0.001 Receiver stability ppm 0.001 Tr
47、ansmit antenna pattern typeOmnidirectional (in horizontal plane) Transmit antenna typeQuarter-wave monopole with ground plane Rec. ITU-R M.1874-1 11 TABLE 2 (continued) Characteristics Units System 1 5 MHz System 2 13 MHz System 3 25 MHz System 4 42 MHz Antenna polarization Vertical Antenna main bea
48、m gain dBi 8 Transmit antenna elevation beamwidth degrees 35 Transmit antenna azimuthal beam width Omnidirectional Transmit antenna horizontal scan rate Fixed antenna Transmit antenna height m 10 4 2 1.2 Receive antenna pattern type Electric and magnetic dipoles Receive antenna type Two crossed loop
49、s and a monopole as single unit Receive antenna polarization Vertical Receive antenna main beam gain dBi 5 Receive antenna elevation beamwidth degrees 45 Receive antenna azimuthal beamwidth degrees 90-360 Receive antenna horizontal scan rate Fixed antenna Receive antenna height m 4 Receiver IF 3 dB bandwidth Hz 500 Receiver noise figure dB 12 with pulsing Minimum discernible signal dBm 147 (500 Hz RBW(5) (specified system noise level) Sweeping interval s 0.5 to 1.0 12 Rec. ITU-R M.1874-1 TABLE 2 (end)
