Maritime SafetyNET Service by Inmarsat

In the vast and unpredictable waters, reliable communication is crucial for ensuring the safety of vessels and crew. Inmarsat’s Maritime SafetyNET service plays a pivotal role in delivering real-time emergency broadcasts and vital safety information to ships worldwide.

This article explores how the service works, its key functions, and how maritime professionals can access and benefit from this essential safety tool.

Accessing the SafetyNET Service

MSI messages are transmitted to LESs providing Inmarsat-C services in accordance with national and international routeing arrangements. Each user interface has its own access procedure and syntax command, which should be checked with the Inmarsat-C LES operator or service provider.

Some LESs may provide e-mail, or internet (direct) drop access to the SafetyNET service that allows registered MSI providers to send EGC messages using e-mail from any computer with access to the internet. Due to the nature of the internet, an e-mail service may not guarantee that EGC messages will be received by the addressed LES without delay and may not support cancellation procedures. For this reason monitoring of all EGC messages is especially important in accordance with MSI Broadcasts (Inmarsat SafetyNET): Message Formatting, Monitoring, EGC Logs, and Quality Control“Monitoring of MSI Broadcasts” above.

Land Earth Station Functions

Messages for transmission via the Understanding Inmarsat SafetyNET: A Vital Tool for Maritime SafetySafetyNET service are received and processed automatically at the LES. Because the system is automatic, the quality of service and information depends on accurate preparation of messages.

Messages are not reviewed for corruption or accuracy at the LES; therefore, the originator must take special care to adhere to the format specified. This dependence on syntax is one of the reasons why MSI providers must monitor the broadcasts they originate.

Participating LESs transmit SafetyNET messages over an inter-station signalling link to the Ocean Region Network Co-ordination Station (NCS) for transmission over the broadcast channel.

Messages will be queued at the LES and scheduled for transmission according to priority and instructions contained in the special address headers (C₁ – priority code and C₄ – repetition code); messages with the highest priority will be transmitted first (i. e. in the order “distress“, “urgency“, “safety“). The originator of each message will specify in the message parameters the desired number of repetitions and the interval between transmissions.

Receiving SafetyNET Broadcasts

The basic requirements of the EGC receiver are that it should 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, MSI providers must repeat their most important unscheduled messages 6 minutes after the first broadcast.

Although the MES receives all SafetyNET messages on the broadcast channel, it may suppress some messages from being displayed or printed automatically.

For example:

1 All messages addressed to geographical areas (circular or rectangular) other than those including the ship’s current position will be automatically suppressed;

2 For coastal warnings only (See figure below) it may be programmed to suppress:

1. Messages containing B₁ codes for coastal warning areas which have not been setup in the terminal;
2. Messages containing B₂ codes for subject matter of no relevance to the ship.

The MES also suppresses the printing of messages previously received. It is not possible to reject mandatory “all ship” messages such as shore-to-ship distress alerts for the area within which the ship is located. When a distress or urgency message is received, an audio and visual alarm will be given.

Note: Figure depicts the general information available on an EGC setup screen. The layout of this screen varies between different models of Inmarsat-C and mini-C MESs.

The following B₂ code subject indicators for coastal warnings are in use:

It is recommended that, in order to ensure that all necessary MSI is available before sailing, the EGC receiver should remain in operation while the ship is in port.

Read also: Empowering Global Communication with INMARSAT Satellites in shipping

Although reception of SafetyNET traffic is automatic, the shipboard operator must set up the receiver properly before the start of the voyage as follows:

1 Selecting the appropriate satellite ocean region.

2 Selecting one or more of the following (as appropriate):

1. Current NAVAREA/METAREA or Sub-Area designator;
2. Additional NAVAREA/METAREA designator(s);
3. Relevant coastal warning area identification letter and subject indicator
   characters;
4. Fixed position(s).

The position in MESs is up-dated automatically from integrated navigational receivers if fitted, or may be up-dated from a separate electronic position-fixing system. If there is no automatic position up-date system installed, it is recommended that the position in the MES is up-dated at least every 4 hours. If the position has not been up-dated for more than 12 hours or is unknown, all SafetyNET messages within the entire satellite ocean region will be printed or stored in the MES.

If the MES is a Class 2 Inmarsat-C terminal (having a common receiver for Inmarsat-C messages and MSI), MSI Broadcasts (Inmarsat SafetyNET): Message Formatting, Monitoring, EGC Logs, and Quality ControlMSI broadcasts will only be received when the terminal is idle. Therefore a Class 2 terminal must not be in use for other communications at the times of scheduled broadcasts. Similarly, it is necessary to ensure that a Class 3 Inmarsat-C MES (having two separate receivers for Inmarsat-C messages and MSI) is tuned to the calling channel of the appropriate satellite at the times of scheduled broadcasts.

Note: More information on different classes of Inmarsat-C and Mini-C MESs you can find below.

EGC receiver specifications

These technical requirements were defined by Inmarsat for equipment manufacturers and have been extracted from the System Definition Manual (SDM) for the Inmarsat-C communications system.

Enhanced Group Call (EGC) receive facilities are used by SOLAS Convention ships as well as ships not required to comply with the requirements of the SOLAS Convention, as amended. It should be noted that EGC receive facilities intended to meet SOLAS Convention requirements must comply with the IMO Recommendation on Performance Standards for Enhanced Group Call Equipment contained in IMO resolution [A.664(16), as amended].

The specific guidance given in this annex has been carefully coordinated to ensure that the automatic functions of the SafetyNET receiver work properly. Land Earth Stations providing Inmarsat-C services for the GMDSS must comply with all relevant aspects of the Inmarsat-C SDM, including provision of the EGC SafetyNET services.

Technical requirements for Enhanced Group Call receivers for SOLAS-compliant MESs

EGC SafetyNET receivers for SOLAS installations

Background. The global maritime distress and safety system (GMDSS) is a radiocommunication system based on satellite and terrestrial technology, designed to improve communications relating to distress and safety of life at sea. It was adopted by the International Maritime Organization (IMO) in 1988, in the form of Amendments to the International Convention for the Safety of Life at Sea (SOLAS), 1974 and came into effect on 1 February 1992. Implementation was completed on 1 February 1999.

It is the responsibility of national Administrations to determine whether a radio installation on board a ship meets the SOLAS requirements. This is done by national Type Acceptance or Approval testing of the sub-systems included in the installation and by inspection of the complete installation by a radio surveyor.

National Type Acceptance testing for SOLAS equipment is usually based on GMDSS specifications and procedures prepared by IMO and the International Electrotechnical Commission (IEC) on their behalf, although other national or regional specifications may be invoked as well.

IMO and IEC documents, which are identified in Understanding Inmarsat SafetyNET: A Vital Tool for Maritime Safety“Inmarsat SafetyNET: Comprehensive Guide to Maritime Safety”, do not only summarize the general requirements for GMDSS equipment, but also the special requirements for EGC SafetyNET receivers for use in SOLAS installations, as specified by IMO/IEC.

A number of the Inmarsat specifications have been completely revised to reflect the latest IMO/IEC requirements, for example, electromagnetic compatibility and environmental requirements.

Principal relevant documents

For Inmarsat-C and mini-C GMDSS compliant MESs with EGC SafetyNET function, the principal relevant documents in addition to the Inmarsat-C SDM are:

1. Performance Standards for Enhanced Group Call Equipment – Annex: Recommendation on Performance Standards for Enhanced Group Call Equipment, published by IMO as resolution [A.664(16), as amended].
2. General Requirements for Shipborne Radio Equipment Forming Part of the Global Maritime Distress and Safety System (GMDSS) and for Electronic Navigational Aids, published by IMO as resolution A.694(17).
3. Performance Standards for Inmarsat Standard-C Ship Earth Stations Capable of Transmitting and Receiving Direct-printing Communications – Annex: Recommendation on Performance Standards for Inmarsat Standard-C Ship Earth Stations Capable of Transmitting and Receiving Direct-printing Communications, published by IMO as resolution A.807(19), as amended by resolution MSC.68(68), annex 4.
4. Shipborne Radio Equipment Forming Part of the Global Maritime Distress and Safety System and Marine Navigational Equipment, published by the IEC as IEC 60945.
5. Global Maritime Distress and Safety System (GMDSS) – Part 4: Inmarsat-C Ship Earth Station and Inmarsat Enhanced Group Call (EGC) Equipment – Operational and Performance Requirements, Methods of Testing and Required Test Results, published by the IEC as IEC 61097-4.
6. Maritime Design and Installation Guidelines (DIGs), Annex B, issue 6 of April 2008 published by Inmarsat at official site.

Introduction

Enhanced Group Calls. Enhanced Group Calls are a message broadcast service transmitted over the Inmarsat-C communications system. The service allows terrestrial information providers to pass messages or data to Class 2 or Class 3 MESs with EGC receivers or Class 0 stand-alone EGC receivers through the Inmarsat-C LESs. The messages are processed at the addressed LES and forwarded to the NCS which transmits them on the common channel.

EGC receiver. An EGC receiver is defined as a single-channel receiver with a dedicated message processor. Mobile Earth Stations of Class 2 and 3 provide an EGC capability in addition to To-Ship and From-Ship messaging capabilities; class 0 MESs are self-contained EGC receivers as shown in Figure.

Note: Most of the existing models of Inmarsat-C and mini-C Maritime terminals on the market are Class 2 MESs.

Type approval. The Inmarsat-C SDM presents the technical requirements and recommendations for an EGC receiver. These requirements must be satisfied before the equipment can be utilized in the Inmarsat system. Procedures for type approval by Inmarsat of a manufacturer’s design are provided in a complementary document entitled Type Approval Procedures for Inmarsat-C and mini-C Ship Earth Stations published by Inmarsat.

General requirements

Mandatory capabilities. The mandatory capabilities of SafetyNET receivers for SOLAS applications are:

1. Continuous reception of an NCS common channel and processing of the information according to the EGC message protocol; a Class 2 Inmarsat-C MES continuously receives the NCS common channel when not engaged in general communications;
2. Automatic recognition of messages directed to fixed and absolute geographical areas and service codes as selected by the receiver operator or based upon input(s) from navigational equipment;
3. SafetyNET receivers meet the requirements of IEC 61097-4 and IEC 60945, and;
4. Where automatic updates are not available, provision is made for a visual indication if the ship’s position has not been updated during the last 12 hours. It is only possible to reset this indication by revalidating the ship’s position.

NCS common channel selection

General EGC receivers are equipped with facilities for storing up to 20 NCS channel numbers.

Four of these are permanently assigned global beam channel numbers and frequencies as follows:

These four channel numbers are stored in ROM and are not alterable.

NCS scanning. Automatic NCS scanning on a regular basis is prohibited in SOLAS SafetyNET receivers. In the event of low signal strength from the satellite, an alarm is raised and the operator is advised to initiate NCS scanning manually.

Message-processing requirements

General. Acceptance or rejection of the EGC service code types is under operator control except that receivers always receive navigational warnings; meteorological warnings, SAR information and To-Ships distress alerts which are directed to a fixed or absolute geographical area within which the receiver is situated.

Display devices. Message display. The display is capable of presenting at least 40 characters per line of text. The EGC receiver ensures that if a word cannot be accommodated in full on one line it is transferred to the next line.

Status display. An indication of EGC carrier frame synchronization (or loss of synchronization) is provided.

Printer requirements. A printer is required for a SOLAS SafetyNET receiver. Received EGC messages may be stored for later printing with an indication to the operator that the message has been received. However, distress or urgency priority calls are directly printed as well as stored.

Means are also provided not to print or store the same EGC message after it has been received error-free and printed. Messages are not printed until completely received. A local audible alarm is sounded to give advanced warning of a printer “paper-low” condition. All SafetyNET messages are annotated with the date and time (UTC) of reception. This information is displayed or printed with the message.

Character codes. For the EGC service, the International Reference Version of the International Alphabet 5 (IA5), also known as ASCII (a standard alphanumerical character set based on 7-bit codes) is used.

Operator control. The following control functions and displays are provided as a minimum:

1 Selection of EGC carrier frequency.

For SOLAS SafetyNET receivers:

2 Means of inputting the following information:

1. MES‘s position co-ordinates;
2. Current and planned (additional) NAVAREA(s)/METAREA(s);
3. Current and planned coastal warning area (B₁ Code), and;
4. Coastal warning subject indicator character (B₂ Code).

Receivers are fitted with operator controls to allow the operator to select desired geographical areas and message categories. Details of the geographical areas and message categories which have been selected for reception by the operator are readily available.

EGC receiver memory capacity requirements. Both temporary and non-volatile memory is required in an EGC receiver for the following purposes:

1. Message buffering;
2. Maintaining message identification records;
3. Storing position co-ordinates and NAVAREA(s)/METAREA(s) data; and
4. Storing expansion of NCS common channel numbers.

EGC receiver addressing. The five basic methods of addressing EGC receivers are:

1. All-mobiles call;
2. Inmarsat system message addressing;
3. Group addressing;
4. Unique addressing; and
5. Geographical area addressing including coastal addressing.

The type of address used in the header of an EGC packet is uniquely determined by the “C2” service code field.

Message identification. All messages are transmitted with a unique sequence number, originating LES ID and service code. Each subsequent transmission of the message contains the original sequence number. This facility allows multiple printing of repeated messages to be inhibited.

Geographical area addressing. Geographical area addressing refers to messages transmitted to MESs in a particular area. The area may be expressed in terms of a fixed, pre-defined area such as the NAVAREA/METAREA, or satellite coastal warning area, or in terms of an absolute geographical address expressed as latitude and longitude coordinates on the surface of the earth. An absolute geographical area address is a representation of a closed boundary on the surface of the earth given in the address field of the message header. The receiver recognizes two forms of absolute geographical addressing: rectangular and circular. Each form is specified in terms of an absolute position in latitude and longitude and further parameters that completely specify the boundary.

In order to process a geographical area address, the receiver shall be programmed with the MES‘s current position. The position may be entered automatically from an integrated or external navigation aid or entered manually. The receiver provides notification to the operator when the position has not been updated for four hours. If the MES‘s position has not been updated for more than 12 hours, or is unknown, all SafetyNET messages will be printed or stored in memory.

A geographical area address is considered valid for a particular MES if its current position falls inside or on the boundary specified by the address. It is a mandatory requirement that the operator be able to select more than one area, so that messages directed to other area(s) of interest can be provided. It is recommended that the operator be able to select at least four areas.

Link performance monitoring. The SafetyNET EGC receiver continuously monitors the received bulletin board error rate (BBER) as a measure of link performance whenever it is tuned and synchronized to a NCS (or LES) TDM. The receiver stores a count of the number of bulletin boards received in error out of the last 100 received. This count is continuously updated frame by frame.

Alarms and indications. The following alarms and indications are provided at a SOLAS SafetyNET receiver and meet the operational requirements for alarms stated in IEC 61097-4.

Distress/Urgency priority call alarm. For SOLAS SafetyNET receivers: Provision is made for a specific audible alarm and visual indication at the position from which the ship is normally navigated to indicate receipt of SafetyNET messages with distress or urgency priority. It is not possible to disable this alarm and it is only possible to re-set it manually, and then only from the position where the message is displayed or printed.

Other alarms and indications:

1. High BBER;
2. Printer paper low;
3. Receiver fault indication;
4. Loss of receiver synchronization, and;
5. Position update.

Additional alarms and indications may be provided at the manufacturer’s discretion.

Electromagnetic compatibility. The interference and electromagnetic compatibility requirements of IEC 60945-applies.

Environmental conditions. SOLAS SafetyNET receivers shall operate satisfactorily under the environmental conditions specified in the SDM. The latest issues of IEC 61097-4 and IEC 60945 apply.

Navigational interface. In order that a receiver’s position may be automatically updated, receivers may be equipped with an interface to navigational instruments. A suggested standard interface is in IEC 61162, Part 1 (NMEA 0183) Standard for Interfacing Electronic Marine Navigational Devices.

Note: The majority of modern maritime MESs have an integrated navigational receiver.

Charges for SafetyNET Services

IMO resolution A.707(17): Charges for Distress, Urgency and Safety Messages Through the Inmarsat System, establishes the arrangements in place for the treatment of charges.

There are no charges to the mariner for reception of SafetyNET messages.

Message transmission charges apply to MSI providers and are set at a special SafetyNET tariff by national telecommunication service providers and LESs offering EGC services.