1、 Recommendation ITU-R M.1084-5(03/2012)Interim solutions for improved efficiencyin the use of the band 156-174 MHz by stations in the maritime mobile serviceM SeriesMobile, radiodetermination, amateurand related satellite servicesii Rec. ITU-R M.1084-5 Foreword The role of the Radiocommunication Sec
2、tor 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 policy
3、 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/ISO/IEC
4、 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/IEC and
5、 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 Broadcast
6、ing 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-satel
7、lite 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 Publication Ge
8、neva, 2012 ITU 2012 All rights reserved. No part of this publication may be reproduced, by any means whatsoever, without written permission of ITU. Rec. ITU-R M.1084-5 1 RECOMMENDATION ITU-R M.1084-5*, *Interim solutions for improved efficiency in the use of the band 156-174 MHz by stations in the m
9、aritime mobile service (1994-1995-1997-1998-2001-2012) Scope This Recommendation provides ways to improve efficiency in the used of the band 156-174 MHz by stations in the maritime mobile service; specifically describes technical characteristics when using channels spaced by 12.5 kHz, migration to n
10、arrow-band channels, an example method for implementing interleaved narrow-band channels at 12.5 kHz offset spacing and assignment of channels numbers to interleaved channels and simplex operation of duplex channels. The ITU Radiocommunication Assembly, considering a) that a common international sys
11、tem is essential for maritime communications to ensure the safety of life at sea; b) that the greatest long-term benefits in spectrum efficiency are gained by using the latest digital or narrow-band transmission techniques; c) that the introduction of new technology or replanning of frequency bands
12、is a significant exercise involving a long period of transition; d) that any new equipment needs to be compatible or be able to co-exist with existing equipment conforming to Recommendation ITU-R M.489; e) that the introduction of new technology should not interrupt the continuous availability of RR
13、 Appendix 18 maritime mobile distress and safety communications in the VHF bands for all users; f) that congestion in the VHF maritime mobile band has become a serious problem in some parts of the world and is continuing to grow; g) that because of this need administrations may decide to take measur
14、es to solve their local congestion problem; h) that RR Appendix 18 makes provision for administrations to apply 12.5 kHz channel interleaving, subject to coordination with affected administrations; j) that the implementation of 12.5 kHz channels requires a standard channel numbering plan; k) that so
15、me administrations have implemented single frequency operation of two frequency channels as a means of alleviating current congestion; *This Recommendation should be brought to the attention of the International Maritime Organization (IMO). *Radiocommunication Study Group 5 made editorial amendments
16、 to this Recommendation in November 2010. 2 Rec. ITU-R M.1084-5 l) that these interim solutions are used by the standard automatic identification system developed in accordance with Recommendation ITU-R M.1371 to meet IMO vessel carriage requirements, recommends 1 that administrations having an urge
17、nt need to resolve congestion, should implement single frequency operation of two frequency channels as an interim expedient measure; 2 that, for administrations having an urgent need to resolve congestion, changing to 12.5 kHz analogue frequency modulation (FM) as an interim expedient may be used t
18、o improve spectrum utilization but should consider the impact on current operations, especially where it involved international shipping using 25 kHz channel spacing; 3 that administrations, when employing 12.5 kHz analogue FM channels as an interim measure, should take appropriate means to avoid in
19、terference to the distress and safety channels and channels affecting the safety of international shipping; 4 that the interim arrangements referred to in recommends 2 and 3 should not prejudice the implementation of the longer term solution resulting from the ongoing studies which may result in the
20、 use of advanced technologies and channelling of bandwidth other than 12.5 kHz; 5 that the interim arrangements referred to in recommends 2 and 3 shall not prejudice the implementation of a single international system for distress and safety communications by the international community in the longe
21、r term; 6 that administrations intending to resolve current congestion problems through the use of narrow-band channels should consider Annex 2 as a guide to migration from 25 kHz channels to narrower bands; 7 that administrations intending to resolve current congestion problems through the use of n
22、arrow-band channels should use equipment conforming to the technical parameters given at Annex 1, whilst taking into account the provisions of RR Appendix 18; 8 that administrations implementing interleaved narrow-band channels at 12.5 kHz offset spacing on an interim basis should consider Annex 3 a
23、s an example of a possible implementation method (different example methods are available with other characteristics than those described in Annex 3); 9 that administrations implementing narrow-band channels at 12.5 kHz should consider Annex 4 for numbering the new channels; 10 that administrations
24、implementing single frequency operation of two frequency channels should consider Annex 4, 3, for numbering the channels; 11 that administrations should, as far as possible, look to the implementation of the latest digital or narrow-band techniques to meet future operational requirements and achieve
25、 the efficient use of the band 156-174 MHz. Rec. ITU-R M.1084-5 3 Annex 1 Technical characteristics for equipment designed to operate in channels spaced by 12.5 kHz Use of equipment implementing these parameters listed below (see Note 1) should only be in accordance with the provisions of RR Appendi
26、x 18: the frequency tolerance for coast and ship station transmitters should not exceed 5 parts in 106; the frequency deviation should not exceed 2.5 kHz. NOTE 1 For information, other characteristics are based on European Telecommunications Standard (ETS) 301 925 published by the European Telecommu
27、nications Standards Institute (ETSI). Annex 2 Migration to narrow-band channels in the maritime mobile service 1 Introduction This Annex considers how in future the maritime-mobile service might migrate to narrow-band channels spaced at 5 kHz or 6.25 kHz apart, using linear or digital modulation. Co
28、nsideration is given to migration from 25 kHz channel spacing as used at present, and from 12.5 kHz if the latter was to be implemented as an interim measure by some administrations. 2 Implications of migration to narrow-band channels 2.1 Migration The most practicable and least disruptive method of
29、 migrating from 25 kHz or 12.5 kHz to 5 kHz or 6.25 kHz would be by interleaving the narrow-band channels with the wider ones and a similar technique can be used in all cases. However because the linear and digital modulation techniques using 5 kHz and/or 6.25 kHz are incompatible with current FM eq
30、uipment, dual mode or additional equipment would be required during the change-over period. 2.2 Interleaving 2.2.1 Interleaving with 25 kHz channels Figures 1 and 2 illustrate how 5 kHz and 6.25 kHz channels could be interleaved with the existing 25 kHz ones. During the change-over period, coast sta
31、tions and ships would be required to equip with narrow-band equipment and move to the new narrow-band channels as they became available. The numbers of new narrow-band channels would be gradually increased during the transition period with the number of 25 kHz channels available correspondingly decr
32、easing. On a specified date all remaining 25 kHz channels would be withdrawn to be replaced by new ones. 4 Rec. ITU-R M.1084-5 The migration from 25 kHz channels is fairly straightforward but some realignment of channel or band edges is likely to be required. FIGURE 1 FIGURE 2 Migration from 25 kHz
33、to 5 kHz channelling Migration from 25 kHz to 6.25 kHz channelling M.1084-0125 kHza) New channels interleaved between the oldb) All new channels after changeover withreadjustment of channel frequenciesa) New channels interleaved between the oldb) All new channels after changeover25 kHz2.2.2 Interlea
34、ving with 12.5 kHz channels Figures 3 and 4 show that the principle for interleaving 5 kHz or 6.25 kHz channels with any interim 12.5 kHz channels is exactly the same as for 25 kHz. However, the final transition is made more complicated in the case of 5 kHz as the channel initially interleaved on th
35、e centre of the 25 kHz band would have to be moved by 2.5 kHz. 2.2.3 Interleaving with 25 kHz and 12.5 kHz channels If some administrations were to move to 12.5 kHz channel spacing as an interim measure, and if the 12.5 kHz channels were interleaved with the 25 kHz channels, future migration to 5 kH
36、z or 6.25 kHz channels would be significantly more complicated. As shown in Fig. 5, the 5 kHz or 6.25 kHz channel would overlap one or other of the wider bandwidth channels. Rec. ITU-R M.1084-5 5 FIGURE 3 FIGURE 4 Migration from 12.5 kHz to 5 kHz channelling Migration from 12.5 kHz to 6.25 kHz chann
37、elling M.1084-0325 kHz25 kHza) New channels interleaved between the oldb) All new channels after changeovera) New channels interleaved between the oldb) All new channels after changeoverFIGURE 5 Inserting a new channel, 5 or 6.25 kHz, on top of 12.5 kHz channels already interleaved between 25 kHz ch
38、annels, increases the overlap of transmissions. Two alternative cases are shown M.1084-0525 kHz 25 kHz12.5 kHz6 Rec. ITU-R M.1084-5 3 Interference The interleaving process has to be done so as to minimize mutual interference. Some measurements of the interference and co-channel performance between i
39、nterleaved linear modulation and 12.5 kHz FM have been made. No similar published information has been identified for narrow-band digital speech. It is however reasonable to assume that interleaving 5 kHz or 6.25 kHz channels between 25 kHz channels will lead to less interference and better co-chann
40、el performance than between 12.5 kHz channels. 4 Conclusions The migration path to either 5 kHz or 6.25 kHz channels would be similar. However, a direct transition from 25 kHz rather than via an interim step of 12.5 kHz would be simpler in that: it would require less channel planning and realignment
41、 of centre frequencies; it would avoid channel overlap if 12.5 kHz channels were interleaved, as an interim measure, with 25 kHz ones; and the interference potential is likely to be less. Clearly interleaving of channels will need to be carefully planned and the use of frequency planning tools will
42、be important. Further field measurements and studies will be needed to provide the necessary information. Annex 3 An example method for implementing interleaved narrow-band channels at 12.5 kHz offset spacing This method could be used when 12.5 kHz operation is included along with digital selective-
43、calling (DSC) operation (see Note 1) and 25 kHz in a single equipment. NOTE 1 DSC operation in this implementation is in full accordance with Recommendations ITU-R M.493, ITU-R M.541, ITU-R M.821 and ITU-R M.825. 1 Receiver performance 1.1 The sensitivity should be equal to or less than 0.3 V for a
44、12 dB signal plus noise plus distortion to noise plus distortion (SINAD) ratio at the output of the receiver for a 1 kHz narrow band frequency modulation (NBFM) modulation tone at 2 kHz peak deviation. 1.2 Adjacent channel rejection should be at least 70 dB for a 12.5 kHz spaced adjacent channel. 1.
45、3 The spurious response and out-of-band rejection ratio should be at least 75 dB. 1.4 The radio-frequency intermodulation rejection ratio should be at least 75 dB. 1.5 The power of any conducted spurious emission, measured at the antenna terminals, should not exceed 2.0 nW at any discrete frequency.
46、 Rec. ITU-R M.1084-5 7 1.6 The effective radiated power (e.r.p.) of any cabinet radiated spurious emission on any frequency up to 70 MHz removed from the carrier should not exceed 10 nW. More than 70 MHz removed from the carrier, the spurious emissions should not exceed 10 nW plus an additional 6 dB
47、/octave in frequency up to 1 000 MHz. 1.7 For receivers with DSC and C4FM capability. C4FM (constant envelope four-level FM) digital modulation in this implementation is compatible with CQPSK (compatible quadrature phase-shift key) modulation for both transmission and reception. 1.7.1 For DSC operat
48、ion on 25 kHz channels, the receiver must be capable of error-free reception of any DSC data packet at 0.3 V. 1.7.2 For DSC operation on interleaved (12.5 kHz offset) channels, the receiver must be capable of error-free reception of a DSC data packet at 0.3 V at a reduced maximum deviation of 2.5 kH
49、z. 1.7.3 For C4FM operation at 9 600 bit/s, the receiver must be capable of error-free reception of a data packet of 512 characters at 0.5 V. Forward error correction (FEC) may be applied to accomplish the error-free reception. 2 Transmitter performance 2.1 The frequency tolerance for coast station transmitters should not exceed one part in 106and that for ship station transmissions should not exceed five parts in 106. 2.2 Spurious emissions on discrete frequencies, when measured in a non-reactive load equal to the nominal output impedance of the transmitter, sh
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