1、 Recommendation ITU-R M.2058-0(02/2014)Characteristics of a digital system, named navigational data forbroadcasting maritime safety and security related informationfrom shore-to-ship in the maritime HF frequency bandM SeriesMobile, radiodetermination, amateurand related satellite servicesii Rec. ITU
2、-R M.2058-0 Foreword 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 w
3、hich Recommendations 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 de
4、scribed in the Common 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 Implementat
5、ion of the Common Patent 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
6、for television BS Broadcasting 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 meteorolog
7、y SF Frequency sharing 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 procedur
8、e detailed in Resolution ITU-R 1. Electronic Publication Geneva, 2014 ITU 2014 All rights reserved. No part of this publication may be reproduced, by any means whatsoever, without written permission of ITU. Rec. ITU-R M.2058-0 1 RECOMMENDATION ITU-R M.2058-0 Characteristics of a digital system, name
9、d navigational data for broadcasting maritime safety and security related information from shore-to-ship in the maritime HF frequency band (2014) Scope This Recommendation describes an HF radio system, named Navigational Data HF (NAVDAT HF), for use in the maritime mobile service, operating in the f
10、requency bands of Appendix 17 for digital broadcasting of maritime safety and security related information from shore-to-ship. The operational characteristics and system architecture of this radio system are included in Annexes 1 and 2. The two different modes of broadcasting data are detailed in An
11、nexes 3 and 4. The NAVDAT HF is complementary to the NAVDAT 500 kHz, described in Recommendation ITU-R M.2010 in terms of radio coverage. Keywords HF, Maritime, NAVDAT, broadcast, digital Abbreviations/Glossary BER Bit error rate DRM Digital radio mondiale DS Data stream GMDSS Global maritime distre
12、ss and safety system GNSS Global navigation satellite system HF High Frequency IMO International Maritime Organization ITU International Telecommunication Union LF Low frequency MER Modulation error rate MF Medium frequency MIS Modulation information stream NAVDAT Navigational Data (the system name)
13、 NAVTEX Navigational Telex (the system name) NBDP Narrow band direct printing NM Nautical mile (1 852 metres) NVIS Near vertical incidence sky wave OFDM Orthogonal frequency division multiplexing QAM Quadrature amplitude modulation PEP Peak envelope power RMS Root mean square 2 Rec. ITU-R M.2058-0 S
14、FN Single frequency network SIM System of information and management S/N Signal-to-noise ratio TIS Transmitter information stream WRC World Radiocommunication Conference The ITU Radiocommunication Assembly, considering a) that high speed data broadcast from shore-to-ships enhances operational effici
15、ency and maritime safety; b) that the existing Maritime Safety Information (MSI) system operating in narrow band direct printing (NBDP) HF has limited capacity; c) that emerging maritime navigation systems increase the demand for data transmission from shore-to-ship; d) that the MF band provides a l
16、imited geographical coverage, recognizing that the Digital Radio Mondiale (DRM) system referenced in Annex 4 has been incorporated in Recommendation ITU-R BS.1514-2, noting that Recommendation ITU-R M.2010 describes the NAVDAT system operating at 500 kHz, recommends 1 that the operational characteri
17、stics for the broadcasting of maritime safety and security related information in the HF frequency bands should be in accordance with Annex 1; 2 that the system architecture of the broadcasting system for maritime safety and security related information in the HF frequency bands should be in accorda
18、nce with Annex 2; 3 that the technical characteristics and modem protocols for digital data transmission of maritime safety and security related information from shore-to-ships in the HF frequency band should be in accordance with Annex 3 or Annex 4; 4 that the frequencies listed in Annex 5, which b
19、elongs to Appendix 17 should be utilized for operating the NAVDAT HF system. Rec. ITU-R M.2058-0 3 Annex 1 Operational characteristics The NAVDAT HF system can use a simple time-slot allocation similar to the NAVTEX system which could be coordinated by IMO. That NAVDAT HF system can also work on sin
20、gle frequency network (SFN) as described in Annex 4. In this case, the transmitters are frequency synchronized and the transmit data must be the same for all transmitters. The NAVDAT HF digital system offers a free broadcast transmission of any kind of message from shore-to-ships with possibility of
21、 encryption. 1 Type of messages Any broadcasting message should be provided by a secure and controlled source. Message types broadcast can include, but are not limited to, the following: safety of navigation; security; piracy; search and rescue; meteorological messages; piloting or harbour messages;
22、 vessel traffic service files transfer. 2 Broadcast modes 2.1 General broadcast These messages are broadcasted for the attention of all ships. 2.2 Selective broadcast These messages are broadcasted for the attention of a group of ships or in a specific navigation area. 2.3 Dedicated message These me
23、ssages are addressed to one ship, using the maritime mobile service identity. 4 Rec. ITU-R M.2058-0 Annex 2 System architecture 1 The broadcast transmission path The NAVDAT system is organized by performing the following functions: System of information and management (SIM): collects and controls al
24、l kinds of information; creates message files to be transmitted; creates transmitting program according to message files priority and need of repetition. Shore network: assures the transportation of the message files from sources to the transmitters. Shore transmitter: receives the message files fro
25、m SIM; translates message files to orthogonal frequency division multiplexing (OFDM) signal; transmits RF signal to the antenna for broadcast to ships. Transmission channel: Transports the HF RF signal. Ship receiver: demodulates the RF OFDM signal; reconstructs the message files; sorts and makes th
26、e message files available for the dedicated equipment according to the message files applications. Figure 1 shows the diagram of the broadcast transmission path. Rec. ITU-R M.2058-0 5 FIGURE 1 NAVDAT HF broadcast transmission path block diagram M.2058-01. .Messagestypes No.1Messagestypes No.nShiprec
27、eiverTransmission channelMARITIME HF BANDSSystem of information and management(SIM)ShoreNetworkShore transmitterControls/signalisationsMessage files1.1 System of information and management The SIM term includes: all the sources that deliver file messages (e.g. meteorological office, safety and secur
28、ity organizations, etc.); the file multiplexer which is an application running on a server; the file multiplexer manager; the shore transmitter manager. All the sources are connected to the file multiplexer through a network. Figure 2 shows the general diagram of the SIM. 6 Rec. ITU-R M.2058-0 FIGUR
29、E 2 NAVDAT system of information and management block diagram M.2058-02 . .Messagestypes No.1Messagestypes No.nFile multiplexerMessage filesFile multiplexermanagerShore transmittermanagerControls/signalisationShorenetwork1.1.1 File multiplexer The file multiplexer: takes delivery of the message file
30、s from the data sources; encrypts the message files when required; formats the file messages with recipient information, priority status and time stamp; sends the message files to the transmitter. 1.1.2 File multiplexer manager The file multiplexer manager is a man-machine interface that enables the
31、 user to, among other tasks: have a look at the message files coming from any source; specify the priority and periodicity of any message file; specify the recipient of any message file; manage the file message encryption. Some of these functionalities may be automated. As an example, the priority a
32、nd the periodicity of a message may be selected according to the source it comes from or the source may specify the priority in the message. 1.1.3 Shore transmitter manager The shore station manager is a man-machine interface connected to the transmitter through the network; it makes it possible to
33、supervise the transmitter status by indications such as: transmit acknowledgment; alarms; effective transmit power; synchronization report; Rec. ITU-R M.2058-0 7 and to control the transmitter parameters, such as: transmit power; OFDM parameters (pilot subcarriers, error coding, etc.); transmission
34、schedule. 1.2 Shore network The shore network can use a broadband link, a low data rate link or a local file sharing. 1.3 Shore transmitter description A coastal transmitting station consists of this minimum configuration: one local server connected to a protected access; one OFDM modulator; one HF
35、RF amplifier; one transmit antenna with matching unit; one GNSS receiver or atomic clock for synchronization; one monitoring receiver with its antenna. 1.3.1 Shore system architecture Figure 3 shows the block diagram of an HF digital transmitter. FIGURE 3 NAVDAT HF digital transmitter functional blo
36、ck diagram M.2058-03ControllerHF bandsmonitoringreceiverMatchingunitRF amplifierModulatorRF generatorGNSS receiverorreference clockMISTISControls/signalisationsDSTx antennaControls/signalisationsMessage filesShorenetworkControls/signalisationsControls/signalisations1.3.2 Controller The function of t
37、he controller is: to check if the frequency band is free before transmission; to synchronize all signals on the coast station from synchronization clock; to control the transmission parameters, time and schedule; 8 Rec. ITU-R M.2058-0 to format the message files to be transmitted (split files into p
38、ackets). This unit receives some pieces of information: message files from SIM; GNSS or atomic clock for synchronization; HF signal from monitoring receiver; HF modulator and transmitter control signals. 1.3.3 Modulator Figure 4 shows the diagram of the modulator. FIGURE 4 NAVDAT HF modulator functi
39、onal block diagram M.2058-04Pre_encoderEnergydispersalEncoderPre_encoderEnergydispersalEncoderMISTISDSPilotgeneratorOFDMmapperOFDMbase bandgeneratorPre_encoderEnergydispersalEncoderOFDM base band1.3.3.1 Input streams In order to operate, the modulator needs three input streams: modulation informatio
40、n stream (MIS); transmitter information stream (TIS); data stream (DS). These streams are transcoded and then placed on the OFDM signal by the cell mapper ( 1.3.3.3). 1.3.3.1.1 Modulation information stream This stream is used to provide information about: the spectrum occupancy; the modulation for
41、transmission information stream and data stream (4-, 16- or 64-QAM). The MIS is always coded on 4-QAM subcarriers for good demodulation into the receiver. Rec. ITU-R M.2058-0 9 1.3.3.1.2 Transmitter information stream This stream is used to provide information to the receiver about: error coding for
42、 data stream for sky wave propagation, identifier of the transmitter, date and time. The TIS can be coded on 4- or 16-QAM. 1.3.3.1.3 Data stream It contains the message files to transmit (these message files were previously formatted by the file multiplexer). 1.3.3.2 Error correction coding The erro
43、r correction scheme determines the robustness of the coding. The code rate is the ratio between useful and raw data rate. It illustrates the transmission efficiency and can vary from 0.5 to 0.75 depending on the error correction schemes and modulation patterns. 1.3.3.3 Orthogonal frequency division
44、multiplexing generation The three streams (MIS, TIS and DS) are formatted: encoding; energy dispersal. A cell mapper organizes the OFDM cells with the formatted streams and the pilot cells. The pilot cells are transmitted for the receiver to estimate the radio channel and synchronize on the RF signa
45、l. An OFDM signal generator creates the OFDM baseband according to the output of the cell mapper. 1.3.4 HF RF generator A HF RF generator transposes the baseband signal to the final frequency RF output carrier. An amplifier brings the RF signal to the desired power. 1.3.5 RF amplifier The function o
46、f this stage is to amplify the HF signal from the generator output to the necessary level to obtain the desired radio coverage. The OFDM transmission introduces a crest factor on the RF signal. This crest factor must stay in the range 7 to 10 dB at the RF amplifier output for a correct modulation er
47、ror rate (MER). The output RF power of shore transmitter can be adjusted up to 10 kW PEP according to the frequencies bands: Maximum output RF power: 4 MHz: 5 kW, 6 MHz: 5 kW, 8 MHz: 10 kW 12 MHz: 10 kW, 16 MHz: 10 kW, 18/19 MHz: 10 kW, 22 MHz: 10 kW 1.3.6 Transmit antenna with matching unit The RF
48、amplifier is connected to the transmit antenna through the impedance matching unit. NOTE Not necessary in case of use of a broadband antenna. 10 Rec. ITU-R M.2058-0 1.3.7 Global navigation satellite system receiver and a backup atomic reference clock The clock is used to synchronize the local contro
49、ller. 1.3.8 Monitoring receiver The monitoring receiver checks that the frequency is free before transmission and offers possibility to check the transmission. 1.4 Transmission channel: radio coverage estimation HF frequencies are fully dependent on rules of sky wave propagation (by reflection from the ionosphere) which are linked to some parameters such as: day or night, hours, seasons, sunspot cycle, type of transmitting antenna, and radio noise o
