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GMDSS

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CONTENTS

(iii)

Foreword … … … … … … … … … … (i)

Summary of Changes … … … … … … … … (ii)

Contents … … … … … … … … … … … (iii)

Introduction … … … … … … … … … … … … … 1

Chapter 1 GMDSS Concept … … … … … … … … … 3

Chapter 2 Basic Principles and Features of GMDSS … … … … 9

Chapter 3 INMARSAT – Distress and Safety Features … … … … 18

Chapter 4 GMDSS Equipment … … … … … … … … 22

Chapter 5 GMDSS Distress, Urgency and Safety Communications … 30

Resources … … … … … … … … … … 42

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introduction

How to Use this Booklet

To obtain the full benefit of this booklet you must work through it in the correct sequence. DON’T skip some of the sections because you think you know them, because they look too easy, or because they look too difficult.

Add your own notes where you think it necessary. If you strike a problem, read the notes again. The resources section below gives suggested further reading and explains how you can get further reading and explains how you can get further help.

When you think you have fully understood the topic, and you have competed all the required actions, you can then tackle the self-test questions. Try to answer these questions without reference to the notes.

To help you navigate around this booklet and quickly find the various sections, symbols are placed in the margins. These symbols indicate the following:-

Important information, which must be read and remembered An action which you must undertake to improve your knowledge of that topic on your own ship. Series of self-test questions, so that you can test your own understanding of the topic.

Reading of topics to get details of the topics.

Indicates Resources.

Indicates areas where learning can be enhanced by Group Activities.

Action

The actions in this handbook must be done carefully. They are designed to

strengthen your knowledge and understanding of the topic as it applies to your own ship. Some may require you to list the equipment on your ship, or to sketch equipment aboard your ship. Don’t do this from memory, go and look at the

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equipment properly, and make sure you understand what each part of that piece of equipment does.

Self-Test Questions

At the conclusion of each topic, you will find some questions. These are for self-testing purposes only, they are not part of your formal assessment. Some are brief True/False questions or Fill in the Blanks while some may require more detailed answers. Think carefully before answering these questions, each is designed to emphasize a particular point, as well as to test your overall knowledge of the topic.

DON’T skip these questions. It is better to make a mistake and learn from that mistake, than to think you know all the answers.

Resources

Most of the information you will require is included in this booklet, however further reading will expand and improve your knowledge of the subjects.

Details of such books are indicated at the end of the Handbook

Perhaps your greatest resource is the knowledge and expertise of faculty teaching you. Don’t be afraid to ask them about the subjects we are dealing with here, and discuss any problems you may have in the understanding of these topics.

Learning can best be improved by doing activities in a group and then discussing

the same to find out the things that were done right or wrong.

The activities that can be undertaken in a group are indicated by this icon.

Group Activities

Good Luck with your progress

Through this Handbook and with

your final assessment Of topics

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1.1 Overview. Global Maritime Distress and Safety System (GMDSS) is a worldwide plan for maritime safety through international cooperation. This system brings together two-way terrestrial communication as well as satellite communication. The old distress safety system was known as Safety of Life at Sea (SOLAS). GMDSS was fully implemented on 01 Feb 1999. All the vessels above 300 GRT have to comply with GMDSS.

1.2 Before introduction of GMDSS in 1992, the way in which a message from a ship in distress was sent had changed very little from those early days. Before GMDSS a radio operator sent a message by Morse code or radiotelephone hoping that another ship (or shore station if within range) would hear the call and respond.

1.3 Satellite Sub-Systems. Two satellite-based systems play an important role in GMDSS, International Maritime Satellite (INMARSAT) and COSPAS-SARSAT. The former provides both GMDSS and commercial services, the latter provides a distress alerting procedure. The various sub-systems in both the satellite services are depicted in Figure 1.1.

GMDSS CONCEPT

Basic Concept of the GMDSS

Fig 1.1 - GMDSS Satellite Sub-Systems

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1.4 Terrestrial Sub-Systems. The land-based communication is based on HF, MF and VHF frequencies from Coastal Radio Stations (CRS).

1.5 Equipment Carriage. A major difference between the GMDSS and the previous 'Wireless Telegraphy' (W/T) and 'Radio Telephony' (R/T) systems is that the equipment to be carried by a ship should be determined by its area of operation rather than by its size.

1.6 Search and Rescue. The GMDSS uses modem technology, including satellite and digital selective calling techniques on the MF, HF and VHF bands (the latter known as 'terrestrial' systems) enabling a distress alert to be transmitted and received automatically over short and long distances. The system allows search and rescue authorities ashore, as well as shipping in the vicinity of the ship in distress to be rapidly alerted to a distress incident so that they can assist in a coordinated search and rescue operation with a minimum of delay.

1.7 Maritime Safety Information. Additionally, GMDSS provides for urgency and safety communications; and the dissemination of Maritime Safety Information (MSI) - navigation and metrological information to ships.

1.8 Because the different radio systems incorporated into GMDSS have individual limitations with respect to range and service provided, the equipment required to be carried by a ship is determined by the ship's area of operation. The GMDSS has divided the world's oceans into four distinct areas. All vessels are required to carry equipment appropriate to the sea area or areas in which they trade.

1.9 GMDSS Operational Areas. A summary of GMDSS Sea Areas is depicted in Figures 1.2, which will be explained in details in the succeeding chapters. The Sea Areas are as follows:-

1.9.1 Area A1. Within the radiotelephone coverage of at least one VHF coast station in which continuous VHF DSC alerting is available.

1.9.2 Area A2. Within the radiotelephone coverage of at least one MF coast station in which continuous MF DSC alerting is available (excluding Sea Area 1).

1.9.3 Area A3. Within the coverage of an INMARSAT geostationary satellite in which continuous alerting is available (excluding Sea Area 2).

1.9.4 Area A4. The remaining sea areas outside areas A1, A2 and A3.

Areas of Operation under the GMDSS

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1.10 The international Convention for the Safety of Life At Sea (SOLAS) is a set of international regulations and standards governing all aspects of merchant ship operation. The convention has been ratified by all major maritime nations which operate through the International Maritime Organization (IMO), an agency of the United Nations. 1.11 Amendments to the 1974 SOLAS Convention concerning radio communication for the GMDSS were published in 1989 and entered into force on 01 Feb 1992.

1.12 All ships over 300 gross tonnage (GRT) on international voyages, and hence subject to the 1974 SOLAS Convention, have been required to comply with the carriage requirement of the GMDSS since 01 Feb 1999.

1.13 This regulation requires that every ship, to which the regulation applies and while at sea, shall be capable of the following:-

1.13.1 Transmitting ship-to-shore Distress Alerts by at least two separate and independent means, each using a different radio communication service. 1.13.2 Receiving shore-to-ship Distress Alerts.

Fig 1.2 - Summary of GMDSS Sea Areas

Introduction of GMDSS

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1.13.3 Transmitting and Receiving Ship-to-ship Distress Alerts.

1.13.4 Transmitting and Receiving search and rescue coordinating

communications.

1.13.5 Transmitting and Receiving on-scene communication.

1.13.6 Transmitting and Receiving locating signals.

1.13.7 Receiving maritime safety information.

1.13.8 Transmitting and Receiving general radio-communications relating

to the management and operation of the vessel.

1.13.9 Transmitting and Receiving bridge-to-bridge communications.

Now that you have been familiarized with

the topic, let’s see how much you have

learnt! Answer the following without

referring to the chapter

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Self-Test Questions

1. The old distress safety system was known as Safety of Life at Sea. (True/False)

2. Amendments to the 1974 SOLAS Convention concerning radio communication for the GMDSS were published in 1989 and entered into force on 01 Feb 1992. (True/False)

3. All the vessels above 300 GRT have to comply with GMDSS. (True/False)

4. All ships over 300 gross tonnages on international voyages and hence subject

to the 1974 SOLAS Convention have been required to comply with the carriage requirement of the GMDSS since 01 Feb 1999. (True/False)

5. GMDSS is applicable for vessels above 500T. (True/False)

6. The globe is divided into 5 GMDSS Areas. (True/False)

7. The fundamental basis of GMDSS is that the responsibility of SAR has shifted

ashore. (True/False) 8. NAVTEX works on INMARSAT. (True/False)

9. There are 5 Network Coordinating Stations for the 5 GMDSS regions.

(True/False) 10. The land-based communication is based on HF, MF and VHF frequencies from

Coastal Radio Stations (CRS). (True/False)

1. All information about GMDSS is available in _____________ publication.

2. Ships sailing in GMDSS Sea Area A2 are to maintain continuous DSC watch on

________________ frequency on MF.

3. The GMDSS authority responsible for coordination of rescue operations is the ____________.

4. Ships sailing in GMDSS Sea Area A2 are to maintain continuous DSC watch on

________________ frequency on MF.

5. Ships sailing in GMDSS Sea Area A2 are to maintain continuous DSC watch on ________________ frequency on MF.

Part A - True & False

Part B - Fill in the Blanks

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6. The convention has been ratified by all major maritime nations, which operate through the ___________________, an agency of the United Nations.

7. The land-based communication is based on HF, MF and VHF frequencies from _____________.

8. Two satellite-based systems play an important role in GMDSS, International Maritime Satellite (INMARSAT) and _________________.

1. The equipment required to be carried by a ship is determined by the ship's area

of operation. Explain why.

2. Write down one line on the 3 types of GMDSS land stations?

3. List down the minimum equipment requirement for GMDSS Sea Area A4.

4. List down the minimum equipment requirement for GMDSS Sea Area A4.

Part C - Short Answers

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2.1 All stations in the Maritime Mobile and the Maritime Mobile-Satellite service shall be capable of offering four levels of priority in the following order:-

2.2 Distress

2.2.1 A distress message indicates that a mobile unit or person is threatened by grave and imminent danger, and requires immediate assistance.

2.2.2 A distress message has absolute priority over all other communications. 2.2.3 Distress calls transmitted by radiotelephony are prefixed by the word 'MAYDAY' sent three times. 2.2.4 Subsequent messages are preceded by the word ‘MAYDAY’ only once.

2.3 Urgency 2.3.1 An urgency message indicates that the calling station has a very urgent message concerning the safety of a mobile unit or person. 2.3.2 An urgency message has priority over all other communication except Distress. 2.3.3 Urgency messages transmitted by radio-telephony are prefixed by the words ‘PAN PAN’ sent three times.

2.4 Safety

2.4.1 A safety message indicates that the calling station has an important navigational or meteorological warning to transmit. 2.4.2 A safety message has priority over all other communications excepting distress and urgency. 2.4.3 Safety messages sent via radiotelephony are prefixed by the word 'SECURITE' sent three times.

PRINCIPLES AND FEATURES OF

GMDSS

Priorities of Communications

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2.5 Routine 2.5.1 A Routine message is not covered by the above categories. 2.5.2 These messages could be personal communication between ships, or between ships and shore.

2.6 Various types of stations are explained below and also depicted in Figure 2.1. 2.7 Ship Stations. A ship station is a radio station established on board a vessel for communications with stations ashore and other ship stations.

2.8 Coastal Radio Stations (CRS).

2.8.1 A coast radio station is a radio station established on land for the purpose of communicating with ships at sea. 2.8.2 Qatar has one VHF CRS at Mesaieed.

2.9 Port Operations Stations. Port operations stations are established for the operational control of ships in and around ports and harbours. They are also known as "Harbour Control" stations. Some of these stations are classified as Vessel Traffic Service (VTS) stations as defined by the International Maritime Organization (IMO) Resolution.

Fig 2.1 - GMDSS Stations

Types of Station in the Maritime Mobile Service

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2.10 Aircraft Stations. Ship stations communicate with aircraft stations during search and rescue operations on designated frequencies. 2.11 Rescue Coordination Centre (RCC). This is the most important link for rescue operations. The RCC Coordinates Search and Rescue (SAR) operations for ships and aircraft. An RCC is connected by various communications links to CRS, Land Earth Stations (LES) and other SAR organisations.

2.12 Radio Telephone. AM is used in MF and HF bands and FM/PM is used in VHF channels. 2.13 Narrow Band Direct Printing (NBDP). NBDP is also known as radio telex. NBDP is used in MF and HF bands to promulgate Maritime Safety Information (MSI – weather reports/navigation warnings). 2.14 Digital Selective Calling (DSC). DSC is a paging technique used to automate the initial call between two stations. DSC is used in the MF, HF and VHF marine bands for distress, urgency and safety alerting. 2.15 Equipment performing the functions of GMDSS are simple to operate and, wherever appropriate, are designed for unattended operation. In addition, Distress Alerts are able to be initiated from the position from which the ship is normally navigated (i.e. the bridge). 2.16 The GMDSS combines various sub-systems - all of which have different limitations with respect to coverage - into one overall system. The following sections summarise the various GMDSS sub-systems. 2.17 Terrestrial Communications - Long Range. Long range services are provided by the use of High Frequencies (HF). Frequencies have been designated in the 4, 6, 8, 12 and 16 MHz HF marine bands to provide means for transmitting and receiving Distress Alerts and for passing distress and safety traffic. Initial calls to and from ships are normally performed by Digital Selective Calling (DSC) techniques, and subsequent communications by either RT or NBDP, as indicated in the DSC message. 2.18 Terrestrial Communications - Medium Range. MF Radio Communications is used for medium range communications. The Persian Gulf is mainly an A3 GMDSS area. 2.19 Terrestrial Communications - Medium Range. Short range services are provided by the use of VHF, DSC for initial calls followed by communications on R/T. 2.20 Satellite Communications - Inmarsat. Satellite communications are used for both Shore to Ship and Ship to Shore directions.

Modes of Communication

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2.21 Ship and Shore Distress Alerting. The GMDSS enables a ship in distress to send a message in various ways, and be virtually certain that the message will be received and acted upon. The distress, urgency or safety message will be picked up by ships in the area, and by shore stations in range (as with the original system), if sent on MF, HF or VHF DSC. It will be picked up by MRCCs if transmitted by Inmarsat or satellite distress beacons, and relayed to coast stations and ship stations as required in these cases.

2.22 Introduction. Equipment requirements for GMDSS vessels vary according to the area (or areas) in which a ship operates. Coastal vessels, for example, only have to carry minimal equipment if they do not operate beyond the range of shore based VHF stations (Sea Area A1). Ships which trade further from land are required to carry MF equipment in addition to VHF (Sea Area A2). Ships which operate beyond MF range are required to carry HF and/or Inmarsat equipment in addition to VHF and MF (Sea areas A3 and A4). 2.23 Minimum Requirements. Every GMDSS ship is required to carry the following minimum equipment (as defined by SOLAS Chapter IV, Regulation 7):

2.23.1 One SART (Two on vessels above 500 GRT). 2.23.2 NAVTEX receiver, in areas where required. 2.23.3 INMARSAT EGC receiver. 2.23.4 406 MHz EPIRB.

2.24 Equipment Carriage in Sea Areas. In addition to carrying the equipment listed in para 2.23 every ship engaged on voyages exclusively in respective Sea Areas shall have the equipment installed as specified in Tables below.:-

Radio Equipment - Sea Area A1

3 406 MHz EPIRB – installed close to, or capable of remote activation from the Bridge

OR 4 VHF DSC EPIRB - installed close to, or capable of remote

activation from the Bridge

Equipment Carriage Requirements for SOLAS Vessels

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Radio Equipment - Sea Area A1 and A2

11 An MF Radio installation – capable of transmitting and receiving, for distress and safety purposes, on the frequencies,

1.1 2187.5 KHz using DSC 1.2 2182 KHz using R/T

Radio Equipment - Sea Area A1, A2 and A3

OPTION 1

5 INMARSAT C Ship Earth Station 6 An MF Radio installation – capable of transmitting and receiving,

for distress and safety purposes, on the frequencies, 1.1 2187.5 KHz using DSC 1.2 2182 KHz using R/T 360 DSC Watchkeeping Receiver operating on 2187.5 KHz

OPTION 2 7 An MF/HF radio installation capable of receiving all distress and

safety frequencies in the bands between 1605 KHz and 4000 KHz, and between 4000 KHz and 27500 KHz on DSC, R/T and NBDP

8 An MF/HF watchkeeping receiver capable of maintaining DSC watch on 2187.5 KHz, 8414.5 KHz, and at least one of the distress and safety DSC frequencies 4207.5 KHz, 6312 KHz, 12577 KHz or 16804.5 KHz at any time

9 406 MHz EPIRB – installed close to, or capable of remote activation from the Bridge, OR,

10 An INMARSAT Ship Earth Station (Fleet 77 or INMARSAT C)

Radio Equipment - Sea Area A1, A2, A3 and A4

An MF/HF radio installation capable of receiving all distress and

safety frequencies in the bands between 1605 KHz and 4000 KHz,

and between 4000 KHz and 27500 KHz on DSC, R/T and NBDP

An MF/HF watchkeeping receiver capable of maintaining DSC

watch on 2187.5 KHz, 8414.5 KHz, and at least one of the distress

and safety DSC frequencies 4207.5 KHz, 6312 KHz, 12577 KHz or

16804.5 KHz at any time

406 MHz EPIRB – installed close to, or capable of remote activation

from the Bridge

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2.25 There are two ways in which distressed vessel may broadcast a distress message, as follows:-

2.25.1 Ship-to-Shore Alerts. These are directed to Coast Stations and Land Earth Stations to the nearest Rescue Coordination Centre (RCC). 2.25.2 Ship-to-Ship Alerts. These are sent using terrestrial radio on VHF and/or MF frequency DSC alert. All ships within range of the frequency being used. Coast Station may also get the alert, if within range.

2.26 Methods of sending alerts are summarized below:-

2.26.1 Area A1

2.26.1.1 VHF Ch 70 using DSC, or,

2.26.1.2 VHF EPIRB.

2.26.2 Area A2

2.26.2.1 Ship-to-ship and Ship-to-shore alert on MF DSC

2.26.2.2 May also transmit Ship-to-shore alert on Satellite EPIRB.

2.26.3 Area A3

2.26.3.1 Ship-to-ship alert on VHF/MF DSC and a Ship-to-shore alert either via Inmarsat C or HF DSC. 2.26.3.2 Satellite EPIRB.

2.26.4 Area A4

2.26.4.1 Ship-to-ship alert on VHF/MF DSC. 2.26.4.2 Ship-to-shore alert on one of the higher HF DSC frequencies (8, 12 or 16 MHz).

2.26.4.3 Ship-to-shore alert on EPIRB.

Types of Alerting from GMDSS Vessels

Methods of Sending Alerts

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2.27 Every GMDSS ship whilst at sea shall maintain a continuous watch on the following:-

2.27.1 VHF DSC Channel 70. 2.27.2 VHF R/T Channel 16. 2.27.3 On the 2 MHz MF DSC frequency 2187.5 KHz, for ships required to be fitted with MF DSC facilities. 2.27.4 On 8 MHz at least one of the 4, 8, 12 or 16 MHz DSC distress frequencies if the ship is fitted with HF DSC facilities. This watch may be kept on a scanning receiver. 2.27.5 Inmarsat shore-ship distress alerts if the ship is fitted with a ship earth station. 2.27.6 For Maritime Safety Information (MSI) broadcasts using the appropriate equipment which the ship is fitted with (NAVTEX/EGC or NDBP)

Now that you have been familiarized with

the topic, let’s see how much you have

learnt! Answer the following without

referring to the chapter

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Self-Test Questions

1. Frequencies have been designated in the 7, 6, 8, 12 and 16 MHz HF marine bands to provide means for transmitting and receiving Distress Alerts and for passing distress and safety traffic. (True/False)

2. Port Operations Stations are also known as Harbour Control stations. (True/False)

3. DSC is a paging technique used to automate the initial call between two

stations. (True/False) 4. Rescue Coordination Centre is the most important link for rescue operations.

(True/False) 5. A merchant ship having Safety message will put PAN PAN (X3) before the

message. (True/False) 6. Met forecast is a category of Maritime Safety Information (MSI). (True/False)

7. NAVTEX works on INMARSAT. (True/False)

8. The RCC Coordinates Search and Rescue (SAR) operations for ships and

aircraft. (True/False)

9. Urgency messages transmitted by radio-telephony are prefixed by the words ‘PAN PAN’ sent three times. (True/False)

10. Ship stations communicate with aircraft stations during search and rescue operations on designated frequencies. (True/False)

1. Ship-to-ship alert on VHF/MF _______ and a Ship-to-shore alert either via Inmarsat C or HF DSC.

2. _______ is a paging technique used to automate the initial call between two

stations.

3. The Persian Gulf is mainly an _______ GMDSS area. 4. Long range services are provided by the use of _______ _______.

5. AM is used in MF and _______ bands and FM/PM is used in VHF channels.

Part B - Fill in the Blanks

Part A - True & False

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6. RT communication Distress frequency in MF band is __________ KHz. 7. If a Distress alert has type of distress included it is called a ________________

alert. 8. Safety messages sent via radiotelephony are prefixed by the word ________

sent three times. 9. Distress calls transmitted by radiotelephony are prefixed by the word ________

sent three times. 10. Port operations stations are established for the operational control of ships in

and around ports and harbours. They are also known as _____________ stations.

1. A merchant ship, Sea Princess, MMSI No 412348763, Callsign ATWZ is in GMDSS Sea Area A1. A crew member has suffered a heart attack and is serious. Write the RT call which the ship will make and indicate the channel on which the operator will make the call.

2. What are the four levels of message priorirty?

3. What is DSC?

4. What are the two types of Alerting from GMDSS Vessels?

Part C - Short Answers

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3.1 INMARSAT has the following two main equipment for use in GMDSS for Distress and Safety:-

3.1.1 INMARSAT C. 3.1.2 Fleet F77.

3.2 Ship-to-Shore Distress Alerting. The Inmarsat system provides priority alerting for use in distress emergency situations. Distress priority alerting applies not only with respect to satellite channels but also to the automatic routing of the call to the appropriate Rescue Co-ordination Centre (RCC). Each LES in the system provides reliable communication with an RCC. The means of LES-RCC interconnection may vary from country to country. It may also include the use of dedicated lines or public switched networks.

3.3 Inmarsat-C Distress Alerting. Inmarsat-C MESs (Figure 3.1) use the signalling channel for distress alerting. Using the distress button, a short pre-formatted alert is transmitted directly to an LES or to an NCS as a back-up. Distress priority ensures special processing at the LES for rapid transmission to the associated RCC. The distress-alerting format in an Inmarsat-C MES may be updated manually from the terminal keyboard. Automatic position updating, however, may be provided by an integrated electronic navigation receiver (such as GPS) or by direct input from the ship’s electronic navigation system.

INMARSAT – DISTRESS AND

SAFETY FEATURES

Fig 3.1 - INMARSAT C Equipment

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3.4 Inmarsat Fleet F77. Distress alerting from Inmarsat Fleet F77 offers the most comprehensive GMDSS functions of all the Inmarsat family. It offers call prioritisation to four levels (see Figure 3.2) and real-time, hierarchical call pre-emption in both directions. This means that Inmarsat land earth stations (LESs) must be capable of offering this valuable safety addition. With Inmarsat Fleet F77, the rescue authorities will always get a call through to a ship, even if the voice or data channel is being used continuously.

3.5 RCC to Ships. For the co-ordination and control of SAR operations, RCCs require communications with the ship in distress as well as with units participating in the operation. The methods and modes of communication used will be governed by the capabilities available onboard the ship in distress, as well as those onboard the rescue units. Where ships are equipped with Mobile Earth Stations (MESs), the advantages of the Inmarsat system: rapid, reliable communications, including the receipt of Maritime Safety Information (MSI), can be exploited.

3.6 RCC to RCC. Reliable links among RCCs are important for the GMDSS, since a distress message may be received by an RCC thousands of miles away from where assistance is needed, and it may not be the RCC best suited to provide the necessary assistance. In such cases, prompt relay of the distress message to the appropriate RCC by any communications means, whether landlines, terrestrial radio networks or satellite links, is essential. To increase the speed and reliability of inter-RCC communications, some RCCs have installed MESs, which allow them to communicate via the Inmarsat system. These facilities are useful for long-distance communications with SAR organisations, especially when dedicated lines or public switched networks are unavailable or unreliable, as well as for

Fig 3.2 - Fleet F77 Priority Selection

Search and Rescue (SAR) Coordination Communications

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Self-Test Questions

communications with ships. 3.7 On-Scene Communications. On-scene communications are those between SAR vessels and the On-Scene Commander (OSC), or the Coordinator, surface search (CSS). These are normally short-range communications made on the VHF or MF distress and safety frequencies in the GMDSS. However, Inmarsat MES-fitted ships can, if necessary, use satellite communications to supplement their VHF and MF facilities.

1. Pacific Ocean region is covered by two Inmarsat satellites. (True/False)

2. Inmarsat provides reliable coverage between latitudes 80° North and 80° South for both SOLAS and non-SOLAS vessels and available free of charge. (True/False)

3. Inmarsat stands for International Maritime Satellite Organisation. (True/False)

4. The “heart” of the Inmarsat system is the NCS, which operates 24 hours a day, monitors, co-ordinates and controls the operational activities of all satellites in the network. (True/False)

5. Inmarsat is the only provider of GMDSS-approved satellite communications systems. (True/False)

6. Inmarsat C does not provide any storage capability for messages. (True/False) 7. In Inmarsat Fleet 77, the radius of the antenna in cms is 77. (True/False)

8. Satellite segments are space segment, ground segment and user segment. (True/False)

Now that you have been familiarized with

the topic, let’s see how much you have

learnt! Answer the following without

referring to the chapter

Part A - True & False

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9. The ocean regions covered by Inmarsat also includes Arctic Ocean region. (True/False)

10. Distress priority alerting applies not only with respect to satellite channels but also to the automatic routing of the call to the appropriate Rescue Co-ordination Centre (RCC). (True/False)

1. In Inmarsat Fleet 77, Fleet 55 and Fleet 33 systems, 77, 55 and 33 are

______________ of the antenna in cms.

2. The regions covered by Inmarsat are ________________, _________________, and _________________________.

3. Network Operations Centre (NOC) of INMARSAT is located at Inmarsat’s ___________ headquarters.

4. Two Inmarsat satellites cover __________Ocean region.

5. The “heart” of the Inmarsat system is the ________, which operates 24 hours a

day, monitors, co-ordinates and controls the operational activities of all satellites in the network.

6. The only GMDSS-approved satellite communications systems provider is

___________. 7. Inmarsat C provides ___________and forward capability for messages.

8. Distress alerting from Inmarsat ________ offers the most comprehensive GMDSS functions of all the Inmarsat family.

9. This means that Inmarsat ___________ must be capable of offering this valuable safety addition.

10. The Inmarsat system provides _______ alerting for use in distress emergencies.

11. What are the parts of the ground segment of the INMARSAT system? .

12. Write a short note on On-screen communications.

13. What are SAR Coordination Communications?

Part B - Fill in the Blanks

Part C - Short Answers

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4.1 Emergency Position Indicating Radio Beacons (EPIRBs) are small, portable, battery operated radio transmitters. They transmit in the 406.0 – 406.1 MHz channel, and are watertight and buoyant. EPIRB works on the COSPAS-SARSAT System.

4.2 The System was developed under a memorandum of understanding among agencies of Canada, former USSR and USA, signed in 1979. Cospas-Sarsat is combined Russian-English acronym. The system comprises of:-

4.2.1 Space segment operating in LEO and GEO.

4.2.2 Ground Segment consisting of satellite receiving stations, known as

Local User Terminals (LUT), and data distribution centres, known as Mission Control Centres (MCC).

GMDSS EQUIPMENT

The COSPAS-SARSAT System

Fig 4.1 - EPIRB Operation

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4.2.3 Emergency Radio Beacons operating at 406MHz.

4.3 Description of System. Search and Rescue elements are carried in American and Russian satellites, as also on some other partner country satellites. These elements are capable of detecting signals on the Earth’s surface transmitted from distress beacons referred to as:-

4.3.1 Emergency Locator Transmitters (ELTs). Used on aircraft.

4.3.2 EPIRBs. On maritime vessels.

4.3.3 Personal Locator Beacons (PLBs). On land.

4.4 The Beacons operate on the 406 MHz frequencies and 121.5 MHz is used for homing of aircraft. Each Beacon has a unique identifier. 4.5 Modes of Operation. After a beacon transmission is detected by the satellite (Figure 4.1), the signal is relayed to the LUT. The LUT after processing for location transmits it to the MRCC. The Cospas-Sarsat system provides two modes for detection of beacon signals, as follows:-

Fig 4.2 - 406 MHz Visibility to COSPAS-SARSAT System

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4.5.1 Real-Time Mode. If the beacon and LUT are there in the footprint of the satellite, the EPIRB transmission is processed immediately. Satellite visibility for 406 Mhz is shown for the whole globe in Figure 4.2. 4.5.2 Global Coverage Mode. In this mode signals from an activated EPIRB is stored in the satellite memory and as a LUT comes into view of the satellite, the signal is relayed.

4.6 EPIRB is required to meet the following requirements:-

4.6.1 Electrical portions are watertight at a depth of 10 m for at least 5 min. 4.6.2 Be automatically activated after floating free.

4.6.3 Be capable of manual activation and manual deactivation.

4.6.4 Be provided with means to indicate that signals are being emitted.

4.6.5 Be capable of floating upright in calm water and have positive stability and sufficient buoyancy in all sea conditions.

4.6.6 Be capable of being dropped into the water without damage from a height of 20 m.

4.6.7 Be capable of being tested, without using the satellite system, to determine that the EPIRB is capable of operating properly.

4.6.8 Be of highly visible yellow/ orange colour and be fitted with retro-reflecting material.

4.6.9 Be equipped with a buoyant lanyard suitable for use as a tether, which should be so arranged as to prevent its being trapped in the ship's structure when floating free.

4.6.10 The battery should have the capacity to operate for at least 48 hours continuously.

4.6.11 Be capable of releasing itself before reaching a depth of 4m.

4.7 406 MHz EPIRB Operation. A 406 MHz EPIRB is a small, self-contained, battery operated radio transmitter (Figure 4.3), which is both watertight and buoyant. 406 MHz EPIRBs are mounted in a special float-free bracket on either the bridge wing, or the compass deck. The hydrostatic release in the bracket is

EPIRB – The Beacon

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designed to release the beacon when the bracket is submerged to a certain depth. All beacons incorporate a multi-position switch that selects the following modes of operation:-

4.7.1 Off (or safe) - the beacon is switched off, and will not transmit. 4.7.2 Armed (or auto} - the beacon will automatically switch on when it is released from the float free bracket by the hydrostatic release mechanism.

4.7.3 On (or manual} - the beacon will switch on and transmit immediately.

4.7.4 Test - activates a built in self-test routine.

4.8 Description. Search and Rescue Radar Transponders (SARTs) are the main means in the GMDSS for locating ships in distress or their survival craft, and their carriage on board ships is mandatory. The SART is a small, battery powered, omni-directional radar receiver and transmitter. The batteries fitted to a SART allow operation in the standby condition for at least 96 h, plus a further 8 h whilst being interrogated. 4.9 Purpose and Method of Operation.

4.9.1 SART operates in the 9 GHz (3 cm or 'X-band') radar frequency band.

SART

Fig 4.3 – EPIRB Equipment

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4.9.2 On receiving a signal from a ship or aircraft radar; transmits a series of response (homing) signals.

4.9.3 The SART (Figure 4.4) can be activated manually or automatically (in some cases) so that it will thereafter respond when interrogated.

4.9.4 These response signals will be seen on the ship or aircraft radar screen as a line of 12 dots (0.64 n miles apart) (Figure 4.5) extending approximately 8 n miles outward from the SART's position along its line of bearing. This unique radar signal is easily recognised and allows the rescue vessel or aircraft to locate the survivors.

Fig 4.4 - SART

Figure 4.5 - Radar Picture when SART operates

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4.10 Introduction. Portable two-way VHF radiotelephone equipment (Figure 4.6) is used for communications between survival craft and rescue vessels. It may also be used for onboard communications on channels 15 and 17. The equipment typically comprises a small hand-held transceiver with integral antenna.

4.11 Features

4.11.1 A transmitter and receiver. 4.11.2 Power 1W.

4.11.3 Capable of operation for at least 8 hrs.

4.11.4 An antenna which may be fixed or mounted separately.

4.11.5 A microphone with a PTT and loudspeaker.

4.11.6 Watertight to a depth of 1m for at least 5 min.

4.11.7 Either of a highly visible yellow/ orange colour or marked with a surrounding yellow/ orange marking strip.

GMDSS PORTABLE VHF RADIO

Fig 4.6 - Portable VHF R/T Equipment

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4.11.8 Capable of operation on the frequency 156.800 MHz (VHF Ch. 16) and on at least one additional channel. Mostly Channels 6, 13, 16 and 73.

4.11.9 Fitted with channels for single-frequency voice communication only (i.e. duplex channels not allowed).

1. MMSI numbers are of 9 digits. (True/False)

2. Life of SART battery is 96 hours of continuous operation. (True/False)

3. The portable GMDSS VHF Radio has a power output of 5W. (True/False)

4. Met forecast is a category of Maritime Safety Information (MSI). (True/False)

5. NAVTEX works on INMARSAT. (True/False)

6. MMSI No of Coast Radio Stations start with the number 0. (True/False)

7. Life of EPIRB battery is 48 hours of continuous operation. (True/False)

8. The coast station responsible for coordinating search and rescue is the NCS. (True/False)

9. Met forecast is a category of Maritime Safety Information (MSI). (True/False)

10. NAVTEX works on INMARSAT. (True/False)

11. SART is based on S-band radar frequency. (True/False)

Self-Test Questions

Part A - True & False

Now that you have been familiarized with

the topic, let’s see how much you have

learnt! Answer the following without

referring to the chapter

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1. MMSI numbers are of ___________ number of digits.

2. Maritime Safety Information (MSI) can be received by a ship on ______________.

3. EPIRB uses _______________satellite system for operation.

4. The portable GMDSS VHF Radio has a power output of ______W.

5. SART works continuously for ______ hours

6. One of the Distress RT communication frequency in HF band is __________ KHz.

7. When SART operates, you can see __________ number of dots or arcs on your radar.

8. MMSI No of Coast Radio Stations start with the number __________.

9. The VHF channel for making a routine DSC call is _______________.

10. Frequency of operation of EPIRB is ______________.

11. First 3 digits of MMSI no. of a ship registered in Qatar will be _____________.

1. Write any 5-communication requirements that can be met by the GMDSS system.

2. Explain the operation of SART.

3. Explain the manual and automatic operation of EPIRB.

4. What are the features of GMDSS Portable VHF Radio?

5. Your ship is 800 nm from Doha. You are Communication Officer of your ship and Captain wants you to send a message to HQ at Doha, which communication equipment will you use?

Part B - Fill in the Blanks

Part C - Short Answers

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5.1 This Chapter provides an overview of the procedures to be used for emergency communications to and from a vessel in distress. 5.2 The important Distress frequencies are tabulated below:-

FREQUENCY BAND DSC CALL FREQUENCY R/T WORK FREQUENCY

MF 2187.5 kHz 2182.0 kHz

HF 4207.5 kHz 4125.0 kHz

HF 6312.0 kHz 6215.0 kHz

HF 8414.5 kHz 8291.0 kHz

HF 12577.0 kHz 12290.0 kHz

HF 16804.5 kHz 16420.0 kHz

VHF Ch 70 Ch 16 (156.8 MHz)

5.3 A distress alert indicates that a mobile unit or person is threatened by grave and imminent danger and requires immediate assistance. Initiation of a distress alert is made simple by the provision of a distress button in all systems 5.4 A distress alert has absolute priority over all other transmissions.

5.5 A distress alert may be from any of the following:-

5.5.1 Digital Selective Call (DSC) transmitted by VHF, MF or HF. 5.5.2 Distress message format from Inmarsat.

5.5.3 Distress call by voice.

5.5.4 Distress alert from EPIRB activation.

DISTRESS

GMDSS DISTRESS, URGENCY AND

SAFETY COMMUNICATIONS

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5.6 Information contained in Distress Alert. Distress alert must provide the identification of the ship and its position. It may also contain the following:-

5.6.1 Nature of distress. 5.6.2 Type of assistance required.

5.6.3 Course and speed of the ship.

5.6.4 Time and any other information which will assist rescue.

Fig 5.1 - Action on Receipt of Distress Alert

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5.7 Action on Receipt of Distress Alert. Inform the Captain. Ship stations

which receive a distress message from another ship which is, beyond any possible

doubt, in their vicinity should immediately acknowledge receipt. However, in areas

where reliable communications with a coast station are practicable, ship stations

should defer this acknowledgment for a short interval to allow the coast station to

acknowledge (Figure 5.1).

5.8 Ship stations which receive a distress message from another ship which, beyond any possible doubt, is not in their vicinity should defer their acknowledgment to allow ships nearer to the distressed ship to acknowledge without interference.

5.9 Distress Alert Relay. If the ship in distress is unable to make a distress alert/ call then any ship in the vicinity of the ship in distress can send a distress alert relay.

5.10 A Maritime Rescue Coordination Centre (MRCC) which receives a distress alert will initiate the transmission of a shore to ship distress alert relay addressed, as appropriate, to all ships, ships in a particular area or to a specific ship. The distress alert relay will be transmitted by the Inmarsat EGC system and also via DSC and radiotelephone communications. The distress alert relay will contain the identification of the ship in distress, its position and any other information which will assist rescue. 5.11 Each MRCC is equipped with specialized facilities to organize and coordinate Search and Rescue (SAR) activities. MRCCs are connected by international telecommunications networks to MRCCs locate in other parts of the world.

5.12 Generation of Distress Calls. An lnmarsat-C ship earth station allows an operator to send two different types of distress call -a brief distress alert, or a detailed message with distress priority. 5.13 Both types of distress call are automatically routed through a LES to its associated MRCC. Initially, the brief distress alert should be sent and, if time permits, a detailed distress priority message should follow.

5.14 The brief distress alert only requires the operation of one or two controls and results in a distress message containing the following pre-programmed information being transmitted:-

5.14.1 The identity of the ship earth station.

Shore to Ship Distress Alert Relays

Inmarsat C

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5.14.2 The nature of the distress (chosen from a menu or "maritime unspecified" if not chosen) 5.14.3 The ship's position, course and speed (from the most recent entry to the equipment).

5.15 If an acknowledgment is not received from both the LES and the MRCC within 5 min, the distress alert is repeated. 5.16 A detailed distress message may be typed into the equipment using the text editor facility in the same way as a normal message. However, distress priority must be selected by the operator before transmission.

5.17 Routing of a Distress Call. Ship earth stations require the operator to select a LES through which to send a distress alert or call. This should be the nearest LES to the distressed vessel. If a LES is not specified either by the equipment or the operator, the distress alert will be routed via the Network Coordination station (NCS) and may result in an unnecessary delay.

5.18 In Fleet F77 a distress call can be made by a ship either by Telex or by Voice. The R/T call will be received by an operator at the relevant MRCC.

5.19 MF and VHF DSC is designed for ship to ship and local ship-shore alerting. 5.20 Once a DSC alert has been transmitted on the MF and/or VHF DSC channel the station in distress should then change to the radio­telephone distress frequency for the band in use and send a voice MAYDAY message after a brief pause to allow other stations to receive the DSC alert. Do not wait for acknowledgment by other stations on the DSC channel.

5.21 A ship sending a 2 MHz DSC distress alert on 2187.5 kHz wilI use 2182 kHz as the radiotelephone channel. In the case of a VHF DSC alert on Channel 70, Channel 16 is used.

5.22 Distress procedures using voice after the DSC alert are:-

5.22.1 Tune the transmitter to the DSC distress channel (Relevant frequency in 2187.5 kHz on MF, channel 70 on VHF). 5.22.2 If time permits, key in or select on the DSC equipment keyboard:-

5.22.2.1 The nature of distress

MF/VHF Distress DSC and R/T Call Proceure

Fleet F77

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5.22.2.2 The ship's last known position (latitude and longitude).

5.22.2.3 The time (in UTC) the position was valid.

5.22.2.4 Type of subsequent distress communication. Telephony (most equipment defaults to this mode.

5.22.3 Transmit the DSC distress alert. 5.22.4 Prepare for the subsequent radiotelephone distress traffic by tuning the transmitter and the radiotelephony receiver to the distress traffic channel in the same band, i.e. 2182 kHz on MF, channel 16 on VHF.

5.22.5 Send the following spoken message on the radiotelephone channel:-

Distress Call

Distress Signal (X3) MAYDAY

MAYDAY

MAYDAY

Word ‘This is’ THIS IS

Name of the Vessel (X3) DUMB LIGHTER

DUMB LIGHTER

DUMB LIGHTER

Call Sign VJER

MMSI No 503121089

Distress Message

Distress Signal MAYDAY

Name of Vessel DUMB LIGHTER

Call Sign VJER

MMSI No 503121089

Position 35 NM WEST OF DOHA LOGHT

Nature of Distress FIRE OUT OF CONTROL

Other Information VESSEL IS A TANKER. 25 CREW ON

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BOARD

End of Message OVER

5.23 When acknowledging by radiotelephony the receipt of a distress alert or a

distress call, the acknowledgement should be given in the following form:-

5.23.1 The distress signal MAYDAY.

5.23.2 The name followed by the call sign, or the MMSI or other

identification of the station sending the distress message.

5.23.3 The words THIS IS.

5.23.4 The name and call sign or other identification of the station

acknowledging receipt.

5.23.5 The word RECEIVED.

5.23.6 The distress signal MAYDAY.

5.24 Reception and Acknowledgment of DSC Distress Alerts.

5.24.1 DSC distress alerts received on 2187.5 kHz or VHF channel 70

are normally acknowledged by radiotelephony on 2182 kHz or channel

16.

5.24.2 Acknowledgment of a DSC distress alert by the use of a DSC

acknowledgment message is normally made by coast stations only.

5.24.3 A ship receiving a distress alert on any DSC channel should

immediately listen on the associated radiotelephone distress

frequency for the voice MAYDAY message from the ship in distress.

5.24.4 Ships receiving a DSC distress alert from another ship should defer

the acknowledgement of the distress alert for a short interval if the ship is

within an area covered by one or more coast stations. This gives the roast

station the time to acknowledge the DSC distress alert first.

Acknowledgement of Radio Telephony

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5.24.5 As soon as possible after this acknowledgment station should

transmit the following information:-

5.24.5.1 Its position.

5.24.5.2 The speed at which it is proceeding and the

approximate time it will take to reach the scene. Example

Distress Signal MAYDAY

Name of the

Vessel

DUMB LIGHTER

Call Sign VJER

MMSI No 503121089

Word ‘This is’ THIS IS

Name of

Vessel

GREY GLORY

Call Sign VVTP

MMSI No 503171225

Words

‘Received

Mayday’

RECEIVED MAYDAY. MY POSITION 52 NM WEST OF

DOHA LOGHT PROCEEDING AT 18 KTS ESTIMATE

AT YOUR POSITION IN ONE HOUR

End of

Message

OVER

5.25 Transmission of urgency messages is carried out in two steps:-

5.25.1 Announcement of the urgency message.

5.25.2 Transmission of the urgency message.

5.26 Announcement. The announcement is carried out by transmission of a

DSC urgency call on the DSC distress and safety channel (2187.5 KHz on MF,

Ch. 16 on VHF). The announcement may be addressed to all stations or to one

station.

URGENCY

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5.27 Message. The transmission of an urgency message is carried out on the

R/T distress channel.

5.28 Procedure. The procedure for the transmission is as follows:-

5.28.1 Tune the MF transmitter to the DSC frequency, 2187.5 KHz or

switch to Ch. 70 on VHF.

5.28.2 Key in or select on the DSC equipment keyboard:-

5.28.2.1 ‘All Ships’ call or the 9 digit identity of the specific

station.

5.28.2.2 The category of the call (urgency).

5.28.2.3 The frequency or channel on which the urgency

message will be transmitted.

5.28.2.4 The type of communication on which the urgency

message will be given (R/T).

5.28.3 Transmit the DSC urgency announcement.

5.28.4 Tune the transmitted to the frequency indicated in the DSC

urgency announcement.

5.28.5 Transmit the urgency message as follows:-

“PAN PAN” - 3 times

“ALL STATIONS”

Or called stations - 3 times

“THIS IS” - The 9 digit identity and the call sign or

other identification of own ship

- The text of the urgency message

5.29 Reception of an Urgency Message. Ships receiving an urgent priority

message should NOT acknowledge receipt via DSC but should tune their MF/ VHF

frequency nominated in the DSC message and await the voice urgency message.

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5.30 Transmission of safety messages is carried out in two steps:-.

5.30.1 Announcement of the safety message. 5.30.2 Transmission of the safety message.

5.31 Announcement. The announcement is carried out by transmission of a

DSC safety call on the DSC distress and safety channel (2187.5 KHz on MF, Ch.

16 on VHF). The announcement may be addressed to all stations or to one station.

5.32 Message. The transmission of a safety message is carried out on the R/T

distress channel.

5.33 Procedure. The procedure for the transmission is as follows:-

5.33.1 Tune the MF transmitter to the DSC frequency, 2187.5 KHz or switch to Ch. 70 on VHF. 5.33.2 Key in or select on the DSC equipment keyboard:-

5.33.2.1 ‘All Ships’ call or the 9 digit identity of the specific station.

5.33.2.2 The category of the call (urgency).

5.33.2.3 The frequency or channel on which the safety message will be transmitted.

5.33.2.4 The type of communication on which the safety message will be given (R/T).

5.33.3 Transmit the DSC safety announcement. 5.33.4 Tune the transmitted to the frequency indicated in the DSC safety announcement.

5.33.5 Transmit the urgency message as follows:-

SAFETY

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“SECURITE” - 3 times

“ALL STATIONS”

Or called stations - 3 times

“THIS IS” - The 9 digit identity and the call sign

or other identification of own ship

- The text of the safety message

5.34 Reception of an Urgency Message. Ships receiving a safety priority

message should NOT acknowledge receipt via DSC but should tune their MF/ VHF

frequency nominated in the DSC message and await the voice safety message.

5.35 HF DSC is primarily designed for long range ship to shore alerting. HF

DSC distress alerts are normally directed to coast stations.

5.36 Choice of HF Band. As a general rule the DSC distress channel in the 8

MHz maritime band (8414.5 kHz) may in many cases be an appropriate first choice

for distress transmissions.

5.37 Transmission of the DSC distress alert in more than one HF band will

normally increase the probability of successful reception of the alert by coast

stations.

5.38 Transmitting the Alert

5.38.1 Tune the transmitter to the chosen HF DSC distress channel (4207.5, 6312, 8414.5, 12577 or 16804.5 kHz). 5.38.2 Follow the instructions for keying in or selection of relevant information on the DSC equipment keyboard as described in the MF /VHF section.

5.38.3 Select the appropriate mode for subsequent communications.

5.38.4 Transmit the DSC distress alert.

5.38.5 Follow up with a Distress message on the relevant HF R/T frequency

HF DSC Procedures

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Self-Test Questions

1. A merchant ship having Safety message will put PAN PAN (X3) before the message. (True/False)

2. A distress alert indicates that a mobile unit or person is threatened by grave and imminent danger and requires immediate assistance. (True/False)

3. A distress alert has absolute priority over all other transmissions. (True/False)

4. Distress alert must provide the identification of the ship and its position. (True/False)

5. A Maritime Rescue Coordination Centre (MRCC) which receives a distress alert will initiate the transmission of a shore to ship distress alert relay addressed, as appropriate, to all ships, ships in a particular area or to a specific ship. (True/False)

6. Each MRCC is equipped with specialized facilities to organize and coordinate Search and Rescue (SAR) activities. (True/False)

7. MRCCs are connected by international telecommunications networks to MRCCs locate in other parts of the world. (True/False)

8. An lnmarsat-C ship earth station allows an operator to send two different types of distress call -a brief distress alert, or a detailed message with distress priority. (True/False)

9. In lnmarsat-C, Ship earth stations require the operator to select a LES through which to send a distress alert or call. (True/False)

10. MF and VHF DSC is designed for ship to ship and local ship-shore alerting. (True/False)

Part A - True & False

Now that you have been familiarized with

the topic, let’s see how much you have

learnt! Answer the following without

referring to the chapter

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1. If an acknowledgment is not received from both the LES and the MRCC within ___________, the distress alert is repeated.

2. In Fleet F77, a distress call can be made by a ship either by Telex or by ________.

3. In Fleet F77, The R/T call will be received by an operator at the relevant _________.

4. Acknowledgment of a DSC distress alert by the use of a DSC acknowledgment message is normally made by ___________________ only.

5. A ship receiving a distress alert on any DSC channel should immediately listen on the associated radiotelephone distress frequency for the voice __________ message from the ship in distress.

6. The transmission of an urgency message is carried out on the _______ distress channel.

7. Ships receiving an urgent priority message should NOT acknowledge receipt via ________ but should tune their MF/ VHF frequency nominated in the DSC message and await the voice urgency message.

8. The transmission of a safety message is carried out on the _______ distress channel.

9. HF DSC is primarily designed for ____________ ship to shore alerting.

10. HF DSC distress alerts are normally directed to ___________.

1. What actions will you take on receipt of a MAYDAY DSC Alert on VHF?

2. A merchant ship, Sea Princess, MMSI No 412348763, Callsign ATWZ is in GMDSS Sea Area A2. A crew member has suffered a heart attack and is serious. Write the DSC Alert which the ship will make and indicate the channel.

3. What action should you take after sending a false or accidental Distress alert on Inmarsat-C?

4. List the actions to be carried out on receipt of a Distress signal.

Part B - Fill in the Blanks

Part C - Short Answers

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RESOURCES

1. Admiralty List of Radio Signals Vol 5. 2. INMARSAT Handbook Issue 4 published by INMARSAT.