1、 Recommendation ITU-R M.493-14 (09/2015) Digital selective-calling system for use in the maritime mobile service M Series Mobile, radiodetermination, amateur and related satellite services ii Rec. ITU-R M.493-14 Foreword The role of the Radiocommunication Sector is to ensure the rational, equitable,
2、 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 functions of the Radiocommunication Sect
3、or 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 referenced in Annex 1 of Resolution ITU-
4、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 the ITU-R patent information database ca
5、n 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 Broadcasting service (television) F Fixed service
6、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-satellite and fixed service systems SM Spectru
7、m 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 Geneva, 2015 ITU 2015 All rights reserved.
8、No part of this publication may be reproduced, by any means whatsoever, without written permission of ITU. Rec. ITU-R M.493-14 1 RECOMMENDATION ITU-R M.493-14* Digital selective-calling system for use in the maritime mobile service (1974-1978-1982-1986-1990-1992-1994-1995-1997-1997-2000-2004-2007-20
9、09-2015) Scope This Recommendation describes the digital selective-calling (DSC) system for use in the maritime mobile service covering general purpose and simplified versions of DSC equipment. A description of a generalized user interface as well as an automated procedure for the operation of shipb
10、orne equipment are also included. Keywords Digital selective calling (DSC), maritime, GMDSS, distress, alert, announcement, class Abbreviations/Glossary dB Decibel DSC Digital selective calling ECC Error check character EPIRB Emergency position-indicating radiobeacon EOS End of sequence HF High freq
11、uency HMI Human machine interface Hz Hertz GMDSS Global maritime distress and safety system ID Identification IEC International electrotechnical commission IMO International maritime organization km Kilometre MID Maritime identification digits MF Medium frequency MMSI Maritime mobile service identit
12、ies ms Millisecond MSC Maritime safety committee n/a This field is not included in this call N North NBDP Narrow-band direct-printing NE North east _ * This Recommendation should be brought to the attention of the International Maritime Organization (IMO). 2 Rec. ITU-R M.493-14 NM Nautical mile (1 N
13、M = 1852 m) NW North west RT Radiotelephony RX Retransmission Rx Receive S South SE South east SOLAS International Convention for the Safety of Life at Sea SW South west Tx Transmit UTC Coordinated universal time VHF Very high frequency The ITU Radiocommunication Assembly, considering a) that select
14、ive-calling in the shore-to-ship, ship-to-ship and ship-to-shore directions would expedite the handling of traffic in the maritime mobile service; b) that the International Maritime Organization (IMO) has listed a number of operational requirements that should be taken into account when designing a
15、general purpose selective-calling system; c) that Chapter IV of the International Convention for the Safety of Life at Sea (SOLAS), 1974, as amended, requires the use of digital selective calling (DSC) for distress alerting and safety calling in the global maritime distress and safety system (GMDSS)
16、; d) that the systems described in Recommendations ITU-R M.476 and ITU-R M.625, can not fully meet the IMO performance standards for shipborne equipment; e) that the DSC system should be applicable to the maritime mobile service, both for international and national needs; f) that it is desirable tha
17、t the DSC system fulfils the requirements of all types of vessels desiring to use it; g) that after experience gained, a need exists to reduce unnecessary alarms and simplify operation of shipborne equipment; h) that in certain applications there may be a need to disable DSC automatic channel switch
18、ing when there is a requirement for vessels to maintain continuous radio watch on a specific radio telephony channel (e.g. port traffic control, bridge-to-bridge communications), recommends 1 that devices or equipment which use DSC channels/frequencies should be in full compliance with one of the de
19、fined classes within this Recommendation; Rec. ITU-R M.493-14 3 2 that DSC equipment should be designed in response to the operational requirements specified within Recommendation ITU-R M.541; 3 that where there is a need for a general purpose DSC system, the system should be designed in accordance
20、with the characteristics given in Annex 1; 4 that where there is a need for simplified versions of DSC equipment, they should be designed in accordance with Annex 2; 5 that shipborne DSC equipment should be designed to provide a simplified user interface, following the examples of good practice set
21、out in Annexes 3 and 4; 6 that in a GMDSS coast radio station installation, sufficient geographical separation should be provided between the DSC distress channel receiver antennas and any transmitting antennas within the installation. This is to avoid any de-sensitization of the DSC distress channe
22、l receivers if any transmitter is used at full power on any designated transmit frequency other than the DSC distress frequencies. Annex 1 General purpose equipment characteristics 1 General 1.1 The system is a synchronous system using characters composed from a ten-bit error-detecting code as liste
23、d in Table A1-1. 1.1.1 The first seven bits of the ten-bit code of Table A1-1 are information bits. Bits 8, 9 and 10 indicate, in the form of a binary number, the number of B elements that occur in the seven information bits, a Y element being a binary number 1 and a B element a binary number 0. For
24、 example, a BYY sequence for bits 8, 9 and 10 indicates 3 (0 4 1 2 1 1) B elements in the associated seven information bit sequence; and a YYB sequence indicates 6 (1 4 1 2 0 1) B elements in the associated seven information bit sequence. The order of transmission for the information bits is least s
25、ignificant bit first but for the check bits it is most significant bit first. 1.2 Time diversity is provided in the call sequence as follows: 1.2.1 Apart from the phasing characters, each character is transmitted twice in a time-spread mode; the first transmission (DX) of a specific character is fol
26、lowed by the transmission of four other characters before the re-transmission (RX) of that specific character takes place, allowing for a time-diversity reception interval of: 400 ms for HF and MF channels, and 33 ms for VHF radio-telephone channels. 1.3 The classes of emission, frequency shifts and
27、 modulation rates are as follows: 1.3.1 F1B or J2B 170 Hz and modulation rate of 100 (bit/s) * (1 30 * 10-6) for use on HF and MF DSC calling channels. When frequency-shift keying is effected by applying audio signals to the input of single-sideband transmitters (J2B), the centre of the audio-freque
28、ncy spectrum offered to the transmitter is 1 700 Hz. When a DSC call is transmitted on HF and MF working channels for public 4 Rec. ITU-R M.493-14 correspondence, the class of emission is J2B. In this case, audio tones with frequencies 1 700 Hz 85 Hz and modulation rate 100 (bit/s) * (1 30 * 10-6) a
29、re used in order for the DSC call to be transmitted. 1.3.2 Frequency modulation with a pre-emphasis of 6 dB/octave (phase modulation) with frequency-shift of the modulating sub-carrier for use on VHF channels: frequency-shift between 1 300 and 2 100 Hz; the sub-carrier being at 1 700 Hz; the frequen
30、cy tolerance of the 1 300 and 2 100 Hz tones is 10 Hz; the modulation rate is 1 200 (bit/s) * (1 30 * 10-6); the index of modulation is 2.0 10%. 1.3.3 The radio-frequency tolerances of new designs of both transmitters and receivers in the MF and HF bands should be: coast station: 10 Hz, ship station
31、: 10 Hz, receiver bandwidth: should not exceed 300 Hz. 1.4 The higher frequency corresponds to the B-state and the lower frequency corresponds to the Y-state of the signal elements. 1.5 The information in the call is presented as a sequence of seven-bit combinations constituting a primary code. 1.5.
32、1 The seven information bits of the primary code express a symbol number from 00 to 127, as shown in Table A1-1, and where: the symbols from 00 to 99 are used to code two decimal figures according to Table A1-2; the symbols from 100 to 127 are used to code service commands (see Table A1-3). 1.6 Wher
33、e the distress alert repetitions described in 11 apply, the following conditions are considered necessary: 1.6.1 the transmitter encoder must provide repetitive transmission of the call sequence in accordance with 11; and 1.6.2 the receiver decoder should provide maximum utilization of the received
34、signal, including use of the error-check character and by using an iterative decoding process with adequate memory provision. 1.7 When the transmission of a DSC distress alert is automatically repeated, ships DSC equipment must be capable of automatically receiving a subsequent distress acknowledgem
35、ent (see Recommendation ITU-R M.541. Rec. ITU-R M.493-14 5 TABLE A1-1 Ten-bit error-detecting code Symbol No. Emitted signal and bit position 1 2 3 4 5 6 7 8 9 10 Symbol No. Emitted signal and bit position 1 2 3 4 5 6 7 8 9 10 Symbol No. Emitted signal and bit position 1 2 3 4 5 6 7 8 9 10 00 01 02
36、03 04 05 06 07 08 09 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 BBBBBBBYYY YBBBBBBYYB BYBBBBBYYB YYBBBBBYBY BBYBBBBYYB YBYBBBBYBY BYYBBBBYBY YYYBBBBYBB BBBYBBBYYB YBBYBBBYBY BYBYBBBYBY YYBYBBBYBB BBYYBBBYBY YBYYBBBYBB BYYYBBBYBB YYYYBBBBYY BBBB
37、YBBYYB YBBBYBBYBY BYBBYBBYBY YYBBYBBYBB BBYBYBBYBY YBYBYBBYBB BYYBYBBYBB YYYBYBBBYY BBBYYBBYBY YBBYYBBYBB BYBYYBBYBB YYBYYBBBYY BBYYYBBYBB YBYYYBBBYY BYYYYBBBYY YYYYYBBBYB BBBBBYBYYB YBBBBYBYBY BYBBBYBYBY YYBBBYBYBB BBYBBYBYBY YBYBBYBYBB BYYBBYBYBB YYYBBYBBYY BBBYBYBYBY YBBYBYBYBB BYBYBYBYBB 43 44 4
38、5 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 YYBYBYBBYY BBYYBYBYBB YBYYBYBBYY BYYYBYBBYY YYYYBYBBYB BBBBYYBYBY YBBBYYBYBB BYBBYYBYBB YYBBYYBBYY BBYBYYBYBB YBYBYYBBYY BYYBYYBBYY YYYBYYBBYB BBBYYYBYBB YBBYYYBBYY BYBYYYBBYY YY
39、BYYYBBYB BBYYYYBBYY YBYYYYBBYB BYYYYYBBYB YYYYYYBBBY BBBBBBYYYB YBBBBBYYBY BYBBBBYYBY YYBBBBYYBB BBYBBBYYBY YBYBBBYYBB BYYBBBYYBB YYYBBBYBYY BBBYBBYYBY YBBYBBYYBB BYBYBBYYBB YYBYBBYBYY BBYYBBYYBB YBYYBBYBYY BYYYBBYBYY YYYYBBYBYB BBBBYBYYBY YBBBYBYYBB BYBBYBYYBB YYBBYBYBYY BBYBYBYYBB YBYBYBYBYY 86 87
40、 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 BYYBYBYBYY YYYBYBYBYB BBBYYBYYBB YBBYYBYBYY BYBYYBYBYY YYBYYBYBYB BBYYYBYBYY YBYYYBYBYB BYYYYBYBYB YYYYYBYBBY BBBBBYYYBY YBBBBYYYBB BYBBBYYYBB YYBBBYYB
41、YY BBYBBYYYBB YBYBBYYBYY BYYBBYYBYY YYYBBYYBYB BBBYBYYYBB YBBYBYYBYY BYBYBYYBYY YYBYBYYBYB BBYYBYYBYY YBYYBYYBYB BYYYBYYBYB YYYYBYYBBY BBBBYYYYBB YBBBYYYBYY BYBBYYYBYY YYBBYYYBYB BBYBYYYBYY YBYBYYYBYB BYYBYYYBYB YYYBYYYBBY BBBYYYYBYY YBBYYYYBYB BYBYYYYBYB YYBYYYYBBY BBYYYYYBYB YBYYYYYBBY BYYYYYYBBY
42、YYYYYYYBBB B = 0 Y = 1 Order of bit transmission: bit 1 first. 6 Rec. ITU-R M.493-14 TABLE A1-2 Packing table for decimal numbers into ten-bit characters The digits for the Thousands of millions D2 Hundreds of millions D1 Tens of millions D2 Millions D1 Hundreds of thousands D2 Tens of thousands D1
43、Thousands D2 Hundreds D1 Tens D2 Units D1 Character 5 Character 4 Character 3 Character 2 Character 1 NOTE 1 Character 1 is the last character transmitted. The digit sequence D2-D1 varies from 00 to 99 inclusive in each character (character 1 to 5 inclusive). The character that represents a particul
44、ar two-decimal figure is transmitted as the symbol number (see Table A1-1) that is identical to that particular two-decimal figure. When the number consists of an odd number of decimal digits, a zero shall be added in front of the most significant position to provide an integral number of ten-bit ch
45、aracters. TABLE A1-3 Use of symbol Nos. 100 to 127 Symbol No. Phasing and unique functions Format specifier(1) Category(1) Nature of distress(1) First telecommand(1) Second telecommand(1) 100 Routine Fire, explosion F3E/G3E All modes TP No reason given(2) 101 Flooding F3E/G3E duplex TP Congestion at
46、 maritime switching centre 102 Geographical area Collision Busy(2) 103 (3) (3) Grounding Polling Queue indication(2) 104 Phasing RX-0 position Listing, in danger of capsizing Unable to comply Station barred(2) 105 Phasing RX-1 position Sinking End of call(4) No operator available(2) 106 Phasing RX-2
47、 position (6) Disabled and adrift Data Operator temporarily unavailable(2) 107 Phasing RX-3 position Undesignated distress Equipment disabled(2) 108 Phasing RX-4 position Safety Abandoning ship Unable to use proposed channel(2) 109 Phasing RX-5 position Piracy/armed robbery attack J3E TP Unable to u
48、se proposed mode(2) 110 Phasing RX-6 position (5) Urgency Man overboard Distress acknowledgement Ships and aircraft of States not parties to an armed conflict Rec. ITU-R M.493-14 7 TABLE A1-3 (end) Symbol No. Phasing and unique functions Format specifier(1) Category(1) Nature of distress(1) First te
49、lecommand(1) Second telecommand(1) 111 Phasing RX-7 position (6) Medical transports (as defined in 1949 Geneva Conventions and additional Protocols)A 112 Distress Distress EPIRB emissionB Distress alert relay Pay-phone/public call officeC 113 F1B/J2B TTY-FEC Facsimile/data according to Recommendation ITU-R M.1081 114 Ships having common interest 115 F1B/J2B TTY-ARQ (6) 116 All ships(7) (6) (6) 117 Ack. RQ (EOS) (6) (6) 118 Test (6) 119 (6) (6) 120 Individual stations (6) (6) 121 Reserved for na
