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GMDSS Handbook
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Annex - 4-3
DRAFT INTERNATIONAL SAFETYNET MANUAL
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FOREWORD
SafetyNET is an international automatic direct-printing satellite-based service for the promulgation of navigational and meteorological warnings, meteorological forecasts and other urgent safety related messages - maritime safety information (MSI) -to ships. It has been developed as a safety service of INMARSAT's enhanced group call (EGC) system to provide a simple and automated means of receiving MSI on board ships at sea and in coastal waters, where appropriate. The information transmitted is relevant to all seagoing vessels and the message selection features ensure that mariners can receive safety information broadcasts which are tailored to their particular needs.
SafetyNET fulfils an integral role in the global maritime distress and safety system (GMDSS) developed by the International Maritime Organisation (IMO) and incorporated into the 1988 amendments to the International Convention for the Safety of Life at Sea (SOLAS), 1974, as a requirement for ships to which the Convention applies. The ability to receive SafetyNET service information will be generally necessary for all ships which sail beyond coverage of NAVTEX and is commended to all administrations having responsibility for maritime affairs and mariners who require an effective MSI service in waters not served by NAVTEX. |
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CONTENTS
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The SafetyNET Concept |
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SECTIONS |
| 1. |
Introduction |
| 2. |
Definitions. |
| 3. |
General features of the enhanced group call (EGC) system |
| 4. |
Operation of the international SafetyNET service |
| 5. |
Promulgation of maritime safety information (MSI) |
| 6. |
Accessing the SafetyNET service |
| 7. |
Coast earth station function |
| 8. |
Broadcast channel characteristics |
| 9. |
Receiving SafetyNET broadcasts |
| 10. |
Charges for SafetyNET services |
| 11. |
Planning SafetyNET services |
| 12. |
Information for mariners and publicity. |
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ANNEXES |
| 1. |
IMO International SafetyNET Co-ordinating Panel -Terms of reference |
| 2. |
IMO Performance Standards |
| 3. |
The INMARSAT System |
| 4 |
Operational guidance
a) Navigational warning services
b) Meteorological services |
| 5. |
Procedure for amending the SafetyNET manual |
| 6. |
Message addressing -Extract from the INMARSAT -C/EGC System Definition Manual (SDM) |
| 7. |
Receiver specifications -Extract from the INMARSAT-C/EGC System Definition Manual (SDM) |
| 8. |
IMO requirements for the availability of the EGC receive facility |
| 9. |
Authorization and registration of information providers |
| 10. |
Table of internationally co-ordinated broadcast schedules |
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1 INTRODUCTION
1.1. This manual describes the structure and operation of the International SafetyNET service. It is intended primarily for national administrations, but may also be useful to the mariner who requires more operational information than is found in manufacturers' equipment manuals.
1.2. SafetyNET provides shipping with navigational and meteorological warnings, meteorological forecasts, shore-to-ship distress alerts chart correction data and other urgent information in accordance with the requirements of the International Convention for the Safety of Life at Sea (SOLAS), 1974, as amended. It is suitable for use in all sizes and types of ships. Figure I illustrates the way the service is structured.
1.3. SafetyNET is a service of INMARSAT's enhanced group call (EGC) system and was specifically designed for promulgation of maritime safety information (MSI) as a part of the global maritime distress and safety system (GMDSS). The EGC system (technically a part of the INMARSAT -C system) provides an automatic, global method of broadcasting messages to all vessels in both fixed and variable geographical areas or to predetermined groups of ships.
1.4. SafetyNET meets the requirements of the International Convention for the Safety of Life at Sea (SOLAS), 1974, as amended for broadcasting area, regional or local navigational warnings, meteorological warnings and forecasts chart correction services and shore-to-ship distress alerts. It is designed with the capability to provide services within the coverage areas of geostationary maritime communications satellites (approximately between 75�N and 75�S). In addition to providing service to ships operating in sea area A3, it also provides the means of disseminating maritime safety information to coastal waters not covered by NAVTEX on 518 kHz.
1.5. SafetyNET offers the ability to direct a call to a given geographical area. The area may be fixed, as in the case of a NAVAREA or weather forecast area, or it may be uniquely defined by the originator. This is used for messages, such as a local storm warning or a shore-to-ship distress alert, for which it is inappropriate to alert ships in an entire ocean region. The general EGC system capabilities are shown in figure 2.
1.6. SafetyNET messages can be originated by a registered information provider anywhere in the world and broadcast to the. appropriate ocean area via an INMARSAT -C coast earth station. Messages are broadcast according to their priority, i.e. distress, urgent, safety, and routine. (See annex 6, paragraph 1.3.1).
1.7. Aboard ship, SafetyNET messages are received through anyone of a number of type-approved equipments.
2 DEFINITIONS
2.1. Coast earth station (CES): A land station in the INMARSAT satellite communications system which provides interconnection between the satellite and shore systems such as telex and telephone -may also be called a land earth station (LES).
2.2. Enhanced group call (EGC): The system for broadcasting messages via the mobile satellite communications system operated by INMARSAT .EGC is a part of the INMARSAT -C system and supports two services: SafetyNET and FleetNET .
2.3. FleetNET: A commercial service for the broadcast and automatic receipt of fleet management and general public information by means of direct-printing through INMARSAT's enhanced group call system. Some receivers for FleetNET may not be able to receive SafetyNET .
2.4. INMARSAT-A: A satellite communication system for transmission of voice, telex, facsimile or data using directional antennas in the INMARSAT satellite system.
2.5. INMARSAT -C: A satellite communications system for telex or data messaging using small terminals and omnidirectional antenrias in the INMARSAT satellite system.
2.6. International NAVTEX service: The system for the broadcast and automatic reception of maritime safety information by means of narrow-band direct-printing on 518 kHz, using the English language. (NAVTEX receiving capability is part of the mandatory equipment which is required to be carried in certain ships under the provisions of chapter IV of the International Convention for the Safety of Life at Sea (SOLAS), 1974, as amended.)
2.7. International SafetyNET service: The co-ordinated broadcast and automated reception of maritime safety information via the INMARSAT enhanced group call system using the English language to meet the requirements of chapter IV of the International Convention for the Safety of Life at Sea (SOLAS), 1974, as amended.
2.8. Maritime safety information (MSI): Navigational and meteorological warnings, meteorological forecasts and other urgent safety-related messages broadcast to ships.
2.9. National SafetyNET service: The broadcast and automated reception of maritime safety information via the INMARSAT enhanced group call system using languages as decided by the Administration concerned.
2.10. Network co-ordination station (NCS): A land station in the INMARSAT satellite communications system which controls channel assignments and other communications functions through a satellite for an entire ocean region.
2.11. Registered information provider: An MSI provider, authorised in accordance with annex 9 of this Manual, which has an agreement with one or more CESs for providing SafetyNET broadcast information.
2.12. Rescue co-ordination centre (RCC): A unit responsible for promoting efficient organisation of search and rescue services and for co-ordinating the conduct of search and rescue operations within a search and rescue region.
2.13. SafetyNET: The international service for the broadcast and automatic reception of maritime safety information by means of direct-printing through INMARSAT's enhanced group call system. (SafetyNET receiving capability is part of the mandatory equipment which is required to be carried in certain ships under the provisions of chapter IV of the International Convention for the Safety of Life at Sea (SOLAS), 1974, as amended.)
2.14. Sea Area A1 : An area within the radiotelephone coverage of at least one VHF coast station in which continuous DSC alerting is available, as may be defined by a Contracting Government.
2.15. Sea Area A2: An area, excluding sea area A1 , within the radiotelephone coverage of at least one MF coast station in which continuous DSC alerting is available, as may be defined by a Contracting Government.
2.16. Sea Area A3: An area, excluding sea areas AI and A2, within the coverage of an INMARSAT geostationary satellite in which continuous alerting is available.
2.17. Sea Area A4: An area outside sea areas At, A2 and A3
2.18. Ship earth station (SES): A mobile earth station in the maritime mobile-satellite service located aboard a ship.
3 GENERAL FEATURES OF THE ENHANCED GROUP CALL (EGC) SYSTEM
3.1. INMARSAT's EGC system is part of the INMARSAT -C system and is complementary to the international NAVTEX service. The EGC system supports two services:
1. SafetyNET -for promulgation of maritime safety information; and
2. FleetNET -for transmission of fleet management and general public information to fleets or groups of ships.
3.2. Virtually all navigable waters of the world are covered by the operational satellites in the INMARSAT system. Each satellite transmits EGC traffic on a designated channel. Any ship sailing within the coverage area of an INMARSAT satellite will be able to receive all SafetyNET messages broadcast over this channel by that satellite. The EGC channel is optimised to enable the signal to be monitored by a small receive-only ship earth station which is dedicated to the reception of EGC messages. This capability can be built into other standard ship earth stations. It is a feature of satellite communications that reception is not generally affected by the position of the ship within the ocean region, atmospheric conditions or time of day.
3.3. Messages can be addressed either to geographical areas (area calls) or to groups of ships (group calls):
1. area calls can be to a fixed geographical area, such as one of the 16 NAVAREAS (figure 3) or to a temporary geographic area selected by the originator. Area calls will be received automatically by any ships whose receiver has been set to one or more fixed areas or recognises a temporary area by the geographic position;
2. group calls will be received automatically by any ship whose receiver acknowledges the unique group identity associated with a particular message.
3.4.Reliable delivery of messages is ensured by forward error correction techniques. Sea trials have demonstrated that the transmission link is generally error free and low-error reception is achieved under normal circumstances .
4 OPERATION OF THE INTERNATIONAL SAFETYNET SERVICE
4.1. Given the "whole ocean" coverage of a single satellite channel, some form of discrimination and selectivity in printing the various messages is required. Area calls will be received by all ships within the ocean region coverage of the satellite. However, they will be printed only by those receivers which recognise the fixed area or the geographical position in the message. The message format includes a preamble which will enable the microprocessor in a ship's receiver to decide to print only those maritime safety information messages which relate to present position, intended route, or to fixed areas programmed by the operator. This preamble, also allows suppression of certain types of maritime safety information which are not relevant to a particular ship.
4.2. As each message will also have a unique identity. the printing of messages already received correctly is automatically suppressed.
4.3. When a message has been received error free, a record is made of the message sequence number and the CES identifier associated with that message. This information is stored in memory and used to inhibit the printing of repeated transmissions of the same message. An EGC receiver is capable of storing at least 250 message identities. As the number of received message identifications exceeds the storage limit, the oldest message identification is erased.
4.4. Reception of certain types of messages, such as shore-to-ship distress alerts and meteorological and navigational warnings, is mandatory and cannot be suppressed by ships in the affected area. These messages are identified by Service Codes (C2) 00, 04, 14, 24, 31, 34, 44 (refer to annex 2, paragraph 3.5).
4.5. SafetyNET messages can be addressed to temporary geographic areas which may be circular (figure 4) or rectangular (figure 5) in shape. A circular area is described by a radius (in nautical miles) from a location specified in degrees of latitude and longitude. A rectangular area is described in degrees of latitude and longitude from the latitude and longitude of the south-west corner of the rectangle.
4.6. In the case of a ship in distress, the need may exist to create a temporary geographic area to facilitate locating potential assisting ships. One approach might be to transmit a shore-to-ship distress alert to a circular area defined by the position of the casualty and a radius about the casualty. This can be done so that only those ships likely to be in the vicinity, potentially in position to help, are alerted. If no response is received from any ship at the first call, the area can, if necessary, be expanded in steps until an acknowledgement by one or more ships is received.
5 PROMULGATION OF MARITIME SAFETY INFORMATION (MSI)
5.1. Maritime safety information is promulgated by various official registered information providers around the world. Messages for transmission through the SafetyNET service will, in many cases, be the result of co-ordination between authorities. Information providers will be registered and authorized to broadcast via SafetyNET by the International Maritime Organization in accordance with the procedures in annex 9. Registered information providers will be:
1. National hydrographic offices for navigational warnings and electronic chart correction data;
2. National weather services for meteorological warnings and forecasts;
3. Rescue co-ordination centres for shore-to-ship distress alerts and other urgent information; and .
4. the International ice patrol for North Atlantic ice hazards.
5.2. Broadcasts of MSI in the International SafetyNET service will be in English; however, there is often a national requirement for broadcasts to be made also in other languages. Guidance on the use of other languages is contained in the relevant technical publications of IMO, IHO and WMO.
5.3. Messages include instructions to the CES for processing the messages in the form of a special address header which consists of 5 "C" codes as described below (see annex 6): |
| C1 is priority code |
-1 digit |
(Distress, urgency, safety, routine) |
| C2 is service code |
-2 digits |
(e.g. Meteorological forecast, etc.) |
| C3 is address |
-12 digits or less |
(e.g. Meteorological warning to circular area) |
| C4 is repetition rate |
-2 digits |
(e.g. Transmit once on receipt) |
| C5 is presentation code |
-2 digits |
(e.g. International Alphabet number S odd parity) |
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5.4. SafetyNET messages are stored at the coast earth station until transmitted the appropriate number of times as specified by the C4 code.
5.5. The originator may also cancel a message before the desired number of repetitions has been made by sending an appropriate cancellation message to the CES: Examples of SafetyNET messages are in annex 4.
5.6. Messages destined for satellite coverage overlap areas and intended to be transmitted through more than one satellite to ensure they are received by all intended ships (which may be working through either satellite) are sent to more than one CES, i.e. one CES in each ocean region. Most authorised MSI providers avoid the necessity for such multiple broadcasts by specifying which satellite will be used to serve particular sea areas and scheduling their broadcasts at fixed times. In an area of overlap coverage from two or three ocean region satellites, urgency warnings will be broadcast over all satellites which cover the affected region. Scheduled broadcasts will be made over nominated satellites and at specified times, as selected by the meteorological and hydrographic services. Tables of these schedules are contained in annex 10.
5.7. In order to ensure the integrity of the maritime safety information being received by mariners, MSI providers must monitor the broadcasts which they originate. Monitoring is especially important in a highly automated system which is .dependent on careful adherence to procedure and format. This may be accomplished by installation of an EGC receive facility ashore for use by each information provider to:
1. check that the message has been broadcast;
2. confirm that the message is received correctly;
3. ensure that cancellation messages are properly executed; and 4. observe any unexplained delay in the message being broadcast
5.8. When an EGC receive facility is established ashore, the most reliable and highest quality reception will normally be achieved with the use of a helical directional antenna.
6 ACCESSING THE SAFETYNET SERVICE
6.1. MSI messages are transmitted by telex, datalink, INMARSAT-A or INMARSAT-C to CESs providing INMARSAT -C services in accordance with national and international routing arrangements. Access to the SafetyNET service will be granted only to registered information providers authorised by IMO and registered with one or more INMARSAT -C CES operators.
6.2. Telex is the standard method for delivery of traffic to the CESs; however, some CESs will have the capability to receive data transmissions from intelligent microcomputers using the X.25 (Packet Switching Protocol) and X.400 message handling standards.
6.3. Alternatively, a rescue co-ordination centre, hydrographic office or meteorological office, with the approval of the national licensing authority and subject to suitable facilities being provided at the CES, may install a ship earth station (SES) on the premises to transmit SafetyNET messages to the serving INMARSAT -C CES, which would then schedule the messages for transmission in the normal manner. The normal INMARSAT communications charges will apply to this method of access, in addition to the EGC broadcast charges. Such an approach could prove particularly attractive to those originators located in countries without a CES, as potential delays and problems in the international terrestrial telecommunications networks could be avoided. It could also serve as an emergency back-up to normal terrestrial communications systems for urgent messages.
6.4. Computer software which can prepare messages for direct telex (and data) input to the EGC system is commercially available.
7 COAST EARTH STATION FUNCTION
7.1. Messages for transmission via the SafetyNET service are received and processed automatically. Because the system is automatic, success depends on accurate preparation of the traffic.
7.2. Messages are not reviewed for corruption or accuracy at the CES; therefore, the originator must take special care to adhere to the format specified in annex 6. It is this dependence on syntax that is one reason why MSI providers must monitor the broadcasts that they originate.
7.3. Participating CESs transmit SafetyNET messages over an interstation signalling link to the ocean region network co-ordination station (NCS) for transmission over the broadcast channel.
7.4. Messages will be queued at the CES according to priority and scheduled for retransmission according to instructions contained in the special address headers (C1 and C4); messages with the highest priority will be transmitted first. Shore-to-ship distress alerts will be broadcast first followed by urgency, safety and then routine traffic. The originator of each message will specify in the message parameters the desired number of repetitions and the interval between transmissions.
8 BROADCAST CHANNEL CHARACTERISTICS
8.1. The modulation rate of the broadcast channel is 1,200 bits per second. Forward error correction is applied to this, creating an effective information transfer of 600 bits per second. (Rate 1/2 convolutional coding with interleaving is used to disperse error bursts which arise when deep fades are present.) This ensures that there is a high probability of receiving a message correctly at the first transmission, irrespective of the atmospheric conditions or the ship's position within the satellite's coverage.
9 RECEIVING SAFETYNET BROADCASTS
9.1. The basic requirements of the EGC receiver are that it shall continuously receive the broadcast channel (the INMARSAT -C NCS common channel) and process the messages being transmitted through the satellite. However, certain classes of receiving equipment may not provide wholly uninterrupted monitoring of the broadcast channel. For this reason, authorised MSI providers will repeat their most important unscheduled messages 6 minutes after the first broadcast.
9.2. Although the receiver receives all SafetyNET messages on the broadcast channel, it incorporates a microprocessor which can be programmed to reject messages for printing automatically, for example:
1. messages concerning subject matter of no relevance to the ship; and
2. messages directed to absolute geographic areas (rectangular or circular) which do not include the ship's position.
9.3. Messages which have been rejected will not be printed. The receiver also inhibits the multiple printing of correctly received messages. It is not possible to reject mandatory ALL SHIP messages such as shore-to- ship distress alerts. When a distress or urgency message is received an alarm will be given.
9.4. Although reception of SafetyNET traffic is automatic, the shipboard operator must set-up the receiver properly at the start of the voyage:
1. Selection of the appropriate broadcast channel (this may be an automatic function). In an area of overlap coverage from two or three ocean region satellites, urgency warnings will be broadcast over all satellites which cover the affected region. Scheduled broadcasts will be made over nominated satellites and at specified times, as selected by the meteorological and hydrographic services. Tables of these schedules are contained in annex 10.
2. The identification code of fixed geographical areas, i.e. NAVAREAs/METAREAs and coastal MSI areas, for which it is desired to receive MSI information, must be put into the receiver .
3. The ship's position must also be keyed-in at periodic intervals or automatically provided through an interface with the ship's electronic position-fixing system. It is recommended that the ship's position in the receiver be updated at least every 4 hours. If the ship's position has not been updated for more than 24 hours, all geographically addressed messages within the entire ocean region will be printed out or stored on disk.
9.5. It is recommended that, in order to ensure that all necessary maritime safety information is available before sailing, the EGC receiver remain in operation while the ship is in port.
9.6. If the ship's EGC receive facility is a Class 2 INMARSAT-C SES, only MSI broadcasts through the satellite whose calling channel is being monitored by the SES will be received. Therefore the Class 2 INMARSAT -C SES must monitor the calling channel of the appropriate satellite at the times of scheduled broadcasts as listed in annex 10. Similarly, it is necessary to ensure that the EGC receive facility in a Class 3 Inmarsat-C SES is tuned to the calling channel of the appropriate satellite at the times of scheduled broadcasts as listed in annex 10.
9.7. If the ship's EGC receive facility shares a directional antenna with an INMARSAT ship earth station (e.g. INMARSAT-A SES), only the MSI broadcast through the satellite which is being tracked by the SES will be received. Therefore, the SES antenna must track the appropriate satellite at the times of scheduled broadcasts as listed in annex 10.
10 CHARGES FOR SAFETYNET SERVICES
10.1. There are no charges to the mariner for receipt of SafetyNET messages.
10.2. Message transmission charges are set by national telecommunication service providers and CESs offering EGC services.
10.3. MSI to be broadcast through the international SafetyNET service is transmitted to the CES via telex, datalink or an INMARSAT-A/INMARSAT -C transmission, for which the normal charges will apply.
11 PLANNING SAFETYNET SERVICES
11.1. Hydrographic, meteorological and search and rescue authorities planning to provide maritime safety information to ships at sea should co-ordinate their plans with other national authorities, and with IHO, IMO and WMO.
11.2. Prospective registered information providers should contact IMO at an early stage for advice and to obtain authorisation to broadcast via SafetyNET. IMO, in co-operation with IHO and WMO, undertakes the co-ordination of times for scheduled transmissions.
11.3. Registered information providers should contact the operators of the coast earth station(s) they desire to use for promulgation of information to their areas of responsibility in order to determine specific details for addressing messages, accessing the CES, charges and payment for services and any other matters with respect to providing MSI to mariners.
11.4. Questions concerning promulgation of MSI through the EGC SafetyNET service can be addressed to the
International SafetyNET Co-ordinating Panel at the address given in annex 1, paragraph 2. Questions concerning the operation of the INMARSAT system should be addressed to
INMARSAT , 40 Melton Street,
London NW1 2EQ, United Kingdom.
12 INFORMATION FOR MARINERS AND PUBLICITY
12.1. The widest publicity should be given to the establishment of SafetyNET services. National administrations should ensure that mariners are informed of the establishment of SafetyNET services by inclusion of full details in Notices to Mariners and Lists of Radio Signals. In addition, full details of the services should be forwarded to:
1. The International SafetyNET Co-ordinating Panel. See annex 1, paragraph 2.
2. Those authorities known to produce Lists of Radio Signals. |
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Annex 1
INTERNATIONAL SAFETYNET CO-ORDINATING PANEL
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1 TERMS OF REFERENCE
To co-ordinate the development and use of the international SafetyNET service, and in particular to:
- develop operating methods for the effective use of the SafetyNET service, including consideration of the need for scheduled broadcasts;
- develop documentation in support of the SafetyNET service, in particular the International SafetyNET Manual;
- co-ordinate tests and trials of SafetyNET services leading to the introduction of a fully operational international service by 1 February 1992;
- advise coast earth station (CES) operators and potential registered information providers on all aspects of the service, including system access and effective operation;
- develop criteria and establish means for the approval and registration of potential information providers;
- co-ordinate the registration of potential information providers; and
- promote a proper understanding of the benefits and use of the international SafetyNET service among the wider maritime community.
2 CONTACT ADDRESS
The SafetyNET Broadcast Co-ordinating Panel can be contacted at the following address:
The Chairman SafetyNET Broadcast Co-ordinating Panel
International Maritime Organization
4 Albert Embankment London
SEI 7SR United Kingdom
Telephone: +4471 7357611 Telex: 23588 IMOLDN G Telefax: +4471 5873210
3 PANEL MEMBERSHIP
1. The SafetyNET Broadcast Co-ordinating Panel is open to membership by all Member Governments and also includes one member nominated by each of the following international organizations:
INTERNATIONAL MARITIME ORGANIZATION (IMO) WORLD METEOROLOGICAL ORGANIZATION (WMO)
INTERNATIONAL HYDROGRAPHIC ORGANIZATION (IHO)
INTERNATIONAL MARITIME SATELLITE ORGANIZATION (lNMARSAT)
2. The following may be represented as observers on the Panel:
IHO Commission on Promulgation of Radio Navigational Warnings
IMO NAVTEX Co-ordinating Panel |
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