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1 INTRODUCTION

Since the invention of radio at the end of the 19th

century, ocean going ships at sea have relied on

Morse code, invented by Samuel Morse and first used

in 1844, for distress and safety telecommunications,

and on radio transceiver invented in early 1895 by

Russian professor of physics Aleksandar Stepanovich

Popov. The need for ship and coast radio stations to

have and use radiotelegraph equipment, and to listen

to a common radio frequency for Morse encoded

distress calls via onboard radio station designed by

Marconi, was recognized after the sinking of the liner

Titanic in the North Atlantic in 1912.

Morse encoded distress calling has saved

thousands of lives since its inception a century ago,

but its use requires skilled radio operators spending

many hours listening to the radio distress frequency.

Its range on the Medium Frequency (MF) distress

band of 500 kHz is limited, and the amount of traffic

Morse signals can carry is also limited. The SOS

distress call was transmitted on dedicated

radiotelegraphy band of 500 kHz, and the voice

distress call Mayday was conducted on

radiotelephony bands of 2182 kHz.

The maritime radio systems for commercial and

distress communications worked very successfully

for several decades and after invention of maritime

satellite communication by the US Marisat in 1976

with only three satellites and ocean networks that are

providing Maritime Satellite Service (MSS) in the

Atlantic, Pacific and Indian Ocean areas. By the end

of the 1980s, maritime satellite communication

services at sea developed by Inmarsat had started to

take an increasingly large share of the market for

ship-to-shore communications.

For these reasons, the International Maritime

Organization (IMO), a United Nations (UN) agency

New Aspects for Modernization Global Maritime

Distress and Safety System (GMDSS)

M. Ilcev

Durban University of Technology, Durban, South Africa

ABSTRACT: This paper describes the new aspects of modernization Global Maritime Distress and Safety

System (GMDSS) proposing new developments and integrations of Radio and Satellite Communication,

Navigation and Surveillance (CNS) and Global Ship Tracking (GST) systems in the function of enhanced Safety

at Sea (SAS) and improved Search and Rescue (SAR) operations. To provide reliable tracking and detecting

facilities of ships in distress have to be integrated the current Maritime Radio Communications (MRC) and

Maritime Satellite Communications (MSC) systems with new Space Communication, Navigation and

Surveillance Systems (CNS). The preliminary modernization aspects and plan for the GMDSS radio and satellite

network are introduced in this paper. Based on the current state of the GMDSS and considerations on updating,

upgrading and improving the system, some normative and technical aspects of the GMDSS modernization

proposals are given. Further proposals on the GMDSS modernization plan were also considered.

http://www.transnav.eu

the International Journal

on Marine Navigation

and Safety of Sea Transportation

Volume 14

Number 4

December 2020

DOI: 10.12716/1001.14.04.26

992

specializing in safety and security of shipping and

preventing ships from polluting the seas, began

looking at ways of improving maritime distress and

safety communications. In 1979, a group of experts

worldwide drafted the International Convention on

Maritime Search and Rescue (SAR), which called for

development of a global SAR plan.

Soon after, this group also passed a resolution

calling for development by IMO of an GMDSS to

provide the communication support needed to

implement the SAR plan more effective. This new

SAR system, which the world’s maritime nations

were implemented, is based upon a combination of

radio and satellite services, and has changed

international distress communications from being

primarily ship-to-ship based to ship-to-shore Rescue

Coordination Center (RCC) based. It spelled the end

of Morse code communications for all but a few

users, such as amateur radio operators and some

military is still using this service.

The GMDSS provides for automatic distress

alerting and locating in cases where a radio operator

doesn’t have time to send an SOS or MAYDAY call,

and, for the first time, requires ships to receive

broadcasts of Maritime Safety Information (MSI) to

prevent a distress from happening in the first place.

In 1988, IMO amended the Safety of Life at Sea

(SOLAS) Convention, requiring ships to fit GMDSS

equipment. Such ships were required to carry

NAVTEX and satellite Emergency Position Indicating

Radio Beacon (EPIRB) units by 1 August 1993, and

had to fit all other GMDSS equipment by 1 February

1999.

2 CURRENT GMDSS NETWORK

The GMDSS plan was adopted by the International

Maritime Organization (IMO) as part of the 1988

amendments to the 1974 International Convention for

the SOLAS-74 and that the system was finally fully

implemented in 1999. The GMDSS architecture

ensures that a ship in distress and emergency

situation anywhere in the world’s oceans must

always be heard and able to provide an answer. The

GMDSS network with space and ground

infrastructures provides for users (ships) and covers a

unique combination of international technical and

operational standards, recommendations and also

includes globally coordinated use of radio

frequencies at both ship and coast stations. The

GMDSS network works well in the maritime industry

and serves faithfully for seafarers onboard ships, but

some of the technologies used in the system do not

reveal their full potential and some functions can be

performed using more modern technologies.

Taking into account the above statements, as well

as the e-Navigation project, at the 86th session of the

Maritime Safety Committee (MSC*), it was decided to

include the sub-item “Analytical research to establish

the need to review the elements and procedures of

the GMDSS” in the work program of the IMO

Subcommittee on Radio Communication and Search

and Rescue (COMSAR Subcommittee). As a result of

this work, in 2012, MSC* approved a new unplanned

exit of the GMDSS Review and Modernization

Project. The project includes a review of High Level

Review (completed in 2014), Detailed Review

(completed in 2016), and the Modernization Plan

(launched in 2016), based on data from previous

work. The COMSAR Subcommittee was entrusted

with being the coordinating body in this matter. At

the end of 2013, after making changes to the

organization of work of the IMO subcommittees, this

issue falls into the competence of the new

subcommittee on Navigation, Radio Communication

and Search and Rescue (NSPS).

The GMDSS network is an integrated system

consisting traditional Maritime Radio

Communications (MRC) and new Maritime Satellite

Communications (MSC), such as Inmarsat and

Cospas-Sarsat subsystems. This integration has to

ensure that no matter where a ship is in distress alert

and aid can be dispatched. It also ensures the

provision of Maritime Safety Information (MSI), both

meteorological and navigational information, on a

global basis at sea. The regulation governing the

GMDSS network is contained in the International

Convention for the Safety of Life at Sea (SOLAS) in

1974. The GMDSS requirements are contained in

Chapter IV of SOLAS on Radiocommunications and

were adopted in 1988.

Figure 1. Current GMDSS Network

In fact, the GMDSS communications system under

SOLAS complements the International Convention on

SAR in 1979 was adopted to develop a global SAR

plan, which current GMDSS network is illustrated in

Figure 1. As already stated, this network is containing

two main subsystems such as Radio and Satellite

networks.

The traditional radio system is providing Very

High Frequency (VHF), the Medium Frequency (MF)

and High Frequency (HF) networks via Coast Radio

Stations (CRS). While, Ships Radio Stations (SRS)

consists onboard ship equipment terminals, such as

Digital Selective Call (DSC), NAVTEX and Search and

rescue radar Transponders (SART).

The Inmarsat Network is providing service for

Ship Earth Stations (SES) via Geostationary Earth

Orbit (GEO) Inmarsat satellites, and Terrestrial

Telecommunication Network (TTN) and Mission

Control Centres (MCC) and RCC to SAR forces. The

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RCC station receives distress signals and via SAR

ships and helicopters give assistance to ships in

distress. The Cospas-Sarsat Network is providing

transmission of EPIRB distress signal via LEOSAR,

GEOSAR and MEOSAR satellites, LUT stations and

MCC, TTN and RCC to SAR forces.

3 MODERNIZATION AND IMPROVEMENTS OF

THE GMDSS SEA OPERATIONAL AREAS

The novel deigns of global Satellite CNS subsystem

and maritime GMDSS equipment include Global Ship

Tracking (GST) as enhanced Long Range

Identification and Tracking (LRIT), Satellite AIS (S-

AIS), Satellite Data Link (SDL), Satellite Automatic

Dependent Surveillance - Broadcast (SADS-B) and

Global Navigation Satellite System (GNSS)

Augmentation SDL (GASDL) to benefit for improved

alerts and SAR operation of ships in distress.

Due to the different radio and satellite

communication systems incorporated into the

GMDSS network having individual coverage

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,

rather than by its size. The GMDSS network has

divided the world’s oceans into four distinct areas.

The current requirements of GMDSS

recommendations and regulations all GMDSS ships

are required to carry onboard equipment appropriate

to the sea area or areas coverage in which they

operate, such as the following operational areas:

1 Sea Area A1 – This are is within the

radiotelephone coverage of at least one VHF coast

station in which continuous VHF Radio DSC

alerting is available in area of approximately of 20-

30 nm range. As stated in abstract, according to

the new technologies and developments in this sea

GMDSS area can be included Radio Ship Tracking

(RST), VHD Data Link (VDL) similar to

aeronautical VDL Mode 4 or new proposed VHF

Data Exchange System (VDES),

Radio-Automatic Identification System (R-AIS)

known as VHF AIS, Radio Automatic Dependent

Surveillance-Broadcast (RADS-B), GNSS (GPS or

GLONASS) Augmentation VDL-Broadcast

(GAVDL-B);

2 Sea Area A2 – This area is within the

radiotelephone coverage of at least one MF coast

station in which continuous MF Radio DSC

alerting is available in sea area of approximately

100 nm range (excluding Sea Area A1). However,

in this area can be used VDL Mode-4 or VDES,

RADS-B and Inmarsat mini-C or Inmarsat-C

service;

3 Sea Area A3 – This large area is within the

coverage area of an Inmarsat GEO satellite

constellation in which continuous alerting is

available in sea area of approximately between 76o

N and 76o S range, (excluding Sea Areas A1 and

A2). Besides, in this area can be used Global Ship

Tracking (GST) proposed by the CNS Systems

company from Durban, Satellite Data Link (SDL),

Satellite Automatic Dependent Surveillance -

Broadcast (SADS-B), GNSS Augmentation SDL

(GASDL), Long Range Identification and Tracking

(LRIT), Orbcomm Satellite-Automatic

Identification System (S-AIS) and HF Data Link

(HDL). Therefore, except Orbcomm S-AIS and

HDL, all above stated satellite communication

solutions can use Inmarsat GEO and Iridium Big

Low Earth Orbit (LEO) satellite constellation;

4 Sea Area A4 – This is the remaining sea coverage

outside areas A1, A2 and A3 (basically in the

range of the Polar Regions). In both polar areas

can be used Iridium satellite constellation

employing equipment such as Iridium GST, SDL

and SADS-B and as well as Orbcomm S-AIS and

HDL.

In this case, there are discussions at IMO that may

result in redefining Sea Areas A3 and A4 based on

satellite coverage of systems other than Inmarsat, if

such systems are approved for use within the

GMDSS. This is not expected to come into force for

several years.

Figure 2. New Concept of GMDSS Network

However, the new concept of enhanced GMDSS

space and ground network is developed and

South Africa, which integrated system architecture, is

illustrated in Figure 2. The main integrated

components of enhanced GMDSS network are Radio

VHF and MF/HF subsystem, Inmarsat GEO and

Iridium Big LEO satellite communication subsystems

and Cospas-Sarsat LEOSAR, MEOSAR and GEOSAR

satellite subsystems. Radio system provides the same

service via VHF and MF/HF bands, such as DSC and

NAVTEX transmissions, including all applications

listed in Sea Area A1 and same in A2, Inmarsat

satellite network provides all service listed in A2 and

A3, while and Iridium satellite network provides

service listed in A4.

In such a way, new concept of GMDSS satellite

system will provide Inmarsat and three Cospas-Sarsat

subsystems including new proposals for Iridium. On

the other hand, the LEO Orbcomm and Medium

Erath Orbit (MEO) O3b networks, including the best

hybrid constellation of GEO and Highly Elliptical

Orbit (HEO) Molniya networks.

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4 DEVELOPING SCOPE FOR PRE-

MODERNIZATION OF THE GMDSS NETWORK

The preliminary modernization plan of the GMDSS

network is prepared by IMO, Inmrsat, Cospas-Sarsat

and other participants is known as Work Program of

the Modernization, which is consisting the following

main components: General provisions; Functional

requirements in accordance with the International

Telecommunications Union (ITU) Radio Regulatio-ns

(RR) and other documents of the ITU-R; The

provision of satellite services to the GMDSS and the

redefinition of the sea area A3; VHF Data Exchange

System (VDES) or known as VDL; Navigation Data

(NAVDAT); Routing distress signals and related

information; Search and Rescue (SAR) technologies;

High Frequency (HF) Data Link (HDL) and radio

communication; Requirements for the transportation

of GMDSS racks; False alerts; Training; Outdated

provisions; and Explanations.

In the process of modernization of the GMDSS, the

following provisions should be taken into account of

the IMO Subcommittee on Navigation, Radio

Communication and Search and Rescue (NCSR)

[NCSR 3, 2016]:

1 Modernization Process – This process and

including new and revised documents, should not

exclude vessels that are not parties to the SOLAS

Convention from any technical and economic

reasons. The documentation and equipment

intended for such vessels must fully comply with

the GMDSS system;

2 Communications Statements – These systems of

the IMO to the radiocommunication sector of the

ITU should be guided by the principle that ships

not party to the SOLAS Convention can use the

GMDSS and the integrity of the system should be

preserved in this case. Including, if necessary,

ITU-R recommendations prescribed for these

vessels the equipment and use of the GMDSS

frequencies;

3 E-navigation System – The GMDSS modernization

project should continue to support the needs of

the new E-navigation strategy; and

4 New Technologies – In order to note the

effectiveness of new technologies, as well as the

compliance with the set goals, the human factor, in

the process of modernization the GMDSS will be

involved both onboard ships and at shore

infrastructures.

Taking into account the above components of the

IMO GMDSS Modernization Plan and a special work

program were adopted that included the revision and

development of regulatory documents, standards and

also reference materials. Thus, the following list is

presenting the necessary actions considered at the

session of the NCSR subcommittee [NCSR 4/12, 2016],

of the IMO coordinated work plan for the

modernization project:

1 In 2018 – The NCSR subcommittee is completing

the development of a Modernization Plan First

draft amendments to the IMO SOLAS Convention

and related documents and finalizing draft

revision of the criteria for the provision of mobile

satellite services;

2 In 2019 – Second draft amendments to the SOLAS

Convention and related documents are provided

together with testing the draft revision of the

criteria for the provision of mobile satellite

services in the GMDSS network;

3 In 2020 – Final draft amendments to the SOLAS

Convention and related documents and draft

functional requirements for NAVDAT have to be

are performed;

4 In 2021 – Approval of amendments to the SOLAS

Convention with related technical documents and

as well as testing functional requirements for

NAVDAT facilities have to be resolved;

5 In 2022 – Adoption of amendments to the SOLAS

Convention (and related documents, as

appropriate) has to be prepared; and

6 In 2023/24 – All proposed amendments to the

SOLAS Convention have to enter into force in a

due course.

5 STANDARDIZATION OF THE PROBLEMS AND

ASPECTS OF A MODERNIZATION PLAN

The GMDSS network is integration complex of radio

and satellite CNS systems, solutions and equipment

intended to provide reliable emergency alert of any

ship in distress situation, to ensure that any distress

message will be received by shore or other ships in

the immediate vicinity, to determine position of ship

in distress, engage SAR operations with improved

means of locating survivors and arrange prompt

saving of their lives. The GMDSS concept was

developed trough the IMO and other contributors to

change the way for conducting maritime distress

communications for enhanced SAR operations. The

GMDSS solutions and equipment are mandatory for

all ships subject to the SOLAS convention, which

include cargo ships of 300 gross tones or greater and

all passenger vessels on international voyages.

The GMDSS network was developed to modernize

and enhance previous emergency ships

radiocommunication system and to provide a more

effective distress alerting by using DSC and other

radio VHF, MF and HF equipment and backed up

with new satellite techniques and technologies. In fact

GMDSS uses various types of radio and satellite

equipment to transmit and receive accurate and real

distress signals and also to improve rescue

communications, coordination and increases the

following tasks:

1 Ability to locate survivors from ship in distress

and including from aircraft landed at sea;

2 Likelihood that distress alert will be received by

shore radio and satellite stations or other ships in

vicinity;

3 Probability that an alert will be sent when a vessel

is in a real distress and not false alert;

4 Capacity to provide mariners with vital Maritime

Safety Information (MSI);

5 It is necessary to define the terms “Security

messages” and “Other messages " and as well as

state the requirements for radio installations to

perform the above functions;

6 Provide the more reliable and effective types of

GMDSS shipborne radio equipment to transmit

and receive accurate and reliable distress signals;

and

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7 Modern tracking systems for maritime

applications are developed in high level, but still

there are problems of reliability of existing

tracking networks and equipment respectively.

Several problems of tracking system for maritime

applications can be further emphasized.

6 TECHNICAL ASPECTS OF THE

MODERNIZATION PLAN

The more critical scenario for distress alerting

situations is when ships are sailing across oceans and

unfriendly coastal areas in very bad weather and sea

conditions, when visible and audibility is almost zero,

when sometimes technically is not possible to use

surveillance radar and when is very difficult to detect

surrounded ships for collision avoidance.

In order to ensure a more reliable, accessible and

efficient situation on board in the event of possible

awareness of distress, it will be necessary to use all

new networks and monitoring and detection

equipment, duchs as VHF-band Data Exchange

System (VDES), Global Ships Tracking (GST) and

GNSS Augmentation Satellite Data Link (GASDL).

6.1 VHF-band Data Exchange System (VDES)

The new VHF-band Data Exchange System (VDES)

was developed by the International Association of

Maritine Aids to Navigation and Lighthouse

Authorities (IALA) to address the emerging signs of

data transmission channel overload in the AIS (VDL)

band and at the same time provides more wide and

unhindered data exchange for the maritime

community. The initial concept of VDES includes the

function of an AIS (R-AIS), Application Specific

Messages (ASM), VHF terrestrial and satellite

communication segments.

The VDES network is one of the potential

elements of E-navigation, which will exchange ASM

transmission, thereby arranging operation of

numerous applications to ensure safety, efficiency

and protection of shipping, as well as environmental

protection. In the future, the VDES network will have

a significant positive impact on MSI network

including Navigation Assistance Services (NAS) and

Vessel Traffic Management System (VTMS).

Figure 3. New Concept of VDES/AIS Network

In Figure 3 is illustrated the new concept of

integrated VDES/AIS Network, which consists

VDES/AIS space segment, ground segment integrated

with GES and VHF GRS terminals and users segment

containing SRS/SES terminals and AIS/SART beacons.

The VDES/AIS Network provides satellite and VHF

radio VDES/AIS links, inter-ship (ship-to-chip)

communications, and AIS/SART signals. Thus, the

AIS signals can be received by the R-AIS receiver and

SART signals can be received by the onboard ships

radars.

Using VDES can potentially provide a local VTMS,

however VDES can also inlude concept deploying a

space (satellite) segment for global coverage. The

space segment of the system can be used for VTMS

transmission in remote areas [Recommendation ITU-

R M.2092-0, 2015]. An insufficient study and

proposals of the issue of sharing and comparability

between the new developed satellite segment of the

VDE system and the existing services in the same and

adjacent frequency ranges caused the operating

frequency range to not be determined at the ITU

World Radiocommunication Conference in 2015

(WRC-2015) .

As a result, VDES as a whole is still not a complete

functional system. As part of the 2015 IGC, the ITU

approved the standard for VDES in the form of

Recommendation ITU-R M.2092-0 [PP, 2015]. The

unresolved issue of the approval of the satellite

segment for data exchange channels in the VHF band

(VDE). The approval of this issue is one of the goals

of the 2019 World Radiocommunication Conference

(WRC-2019).

The study of the vacant frequency ranges

156.0125-157.4375 MHz and 160.6125-162.0375 MHz

will mainly concern interaction with existing mobile

services, primarily for land and sea mobile services,

as well as services within adjacent lower (from 154

MHz up to 156 MHz) and high (from 162 MHz to 164

MHz) frequency ranges. The concept of a VDES

network will be developed under agenda item 1.9.2 at

WRC-19:

1 Amendments to the ITU Radio Regulations (RR),

including new spectrum allocations to the

maritime mobile-satellite service (Earth-to-space

and space-to-Earth), preferably in the frequency

bands 156.0125-157.4375 MHz and 160.6125-

162.0375 MHz of Appendix 18, to create

conditions for the operation of the VDES while

ensuring that this segment does not impair the

operation of existing VDES terrestrial segments,

ASM, AIS network and does not impose any

additional restrictions on existing services in these

and adjacent frequency bands referred to in d) and

e) of the section, recognizing ITU Resolution 360

(Rev. WRC-15).

2 In addition to other applications, the use of VDES

must be considered in all kinds of future VTMS

dissemination mechanisms.

6.2 Global Ship Tracking (GST) Network

The proposed GST network and onboard equipment,

as the best solution for modernization GMDSS, can be

any airborne GPS/Iridium or GPS/Inmarsat

equipment installed together with GPS/Iridium or

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GPS/Inmarsat antenna secretly onboard ship. Because

these devices are not very expensive can be installed

two onboard ships or one as a back up. In fact, the

GST mission can use existing GNSS satellite network

for receiving GNSS signals, a real global Iridium Big

Low Earth Orbit (LEO) satellite network with

intersatellite links or a near-global Inmarsat GEO

satellite network for commercial and distress data

communications.

There are specific shipborne technologies that

were designed for special purposes and they are great

at providing the intended service for the dedicated

solution. For instance AIS is a good global

generalized picture of assets in the loosest terms

possible because it’s not what it was built for. There

are applications where AIS is good to great, safety

while sailing at sea, not getting ran over by a cargo

ship at night or low visibility, etc. But oceangoing

ships need discrete and autonomous systems coming

up that are capable to replace medium to high

intelligence satellite tracking devices such as Global

Ship Tracking (GST), which architecture is illustrated

in Figure 4.

The new GST network has to provide special

Maritime Information Service (MIS) for positioning

data of ships in certain sailing ocean area. Namely,

this service will be an automatically messaging

system of Position, Velocity and Time (PVT) data of

autonomous onboard ships unit containing GPS

receiver, satellite transceiver and own battery power

supply in combination with main ship power supply.

The PVT data will be sent in certain intervals via

Inmarsat or Iridium satellite, Coast Earth Stations

(CES), Internet network to the special and

independent Tracking Control Stations (TCS). Thus,

these TCS terminals will receive, process and store

PVT data of all ship sailing in its ocean area and show

on a special screen similar to the radar display. Each

TCS terminal has to be directly connected to the

MCC, RCC, Ship Traffic Control (STC) and Ship

Traffic Management (STM) systems. In addition, for

enhanced service of collision avoidance, all ships

sailing in certain ocean area can request from TCS

terminals position of all adjacent ships or they simply

can provide polling position data of all adjacent

ships.

In such a way, the TCS terminal can receive PVT

data from any ship, process and display on radar like

display. What LRIT cannot do, GST can provide

determination and surveillance of all ships in certain

sea area for enhanced collision avoidance, assist SAR

to find in shortest time any missing ship, provide

data for immediate detecting position of ship

captured by pirates and it is able to improve GMDSS

facilities.

Figure 4. Maritime GASDL System for Enhanced GMDSS

Network

6.3 Maritime GNSS Augmentation Satellite Data Link

(GASDL) Network

The Regional Satellite Augmentation System (RSAS)

network is a combination of ground monitoring and

space communication infrastructures dedicated to

provide augmentation of standard GPS or GLONASS

signals, which diagram of GNSS Augmentation

Satellite Data Link (GASDL) network is illustrated in

Figure 5. The major functions being provided by

RSAS are as follows: 1. Differential corrections are

determined to improve GNSS signal accuracy; 2.

Integrity monitoring is predisposed to ensure that

errors are within tolerable limits with a very high

probability and thus ensures safety; and 3. Ranging is

proposed to improve availability.

Figure 5. Maritime GASDL System for Enhanced GMDSS

Network

In the same way, the numbers of Reference

Stations (GMS) are receiving not augmented signals

of GPS or GLONASS satellites, processing and

forwarding this data to Master Station (GCS). The

GCS terminals provide processing of GNSS data to

determine the differential corrections and bounds on

the residual errors for each monitored satellite and

for each area. The GCS terminal is providing

determination of the clock, ephemeris and

ionospheric errors (ionospheric corrections are

broadcast for selected area) affected during

propagation. The corrections and integrity

information from the GCS terminal are then sent to

each RSAS Coast Earth Station (CES) and uplinked to

the GEO Satellites.

Thus, these separate differential corrections are

broadcast by RSAS CES through GEO satellite data

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link via GNSS transponder at the same frequency

used by not augmented GPS receiver. For instance,

augmented GPS Rx is receiving augmented signals of

GPS satellite and determining more accurate position

of ships. Not augmented GPS Rx can also receive

augmented signals if is provided an adequate

software or hardware. The most important stage in

this network is to provide technical solution that

augmented position of ships can be sent

automatically via SDL or voice to CES and STC

centre. Finally, these positioning signals can be

processed by special processor and displayed on look

like radar display, whish traffic controller is using for

STC and management for enhanced ship traffic

control and improved collision avoidance in certain

monitoring sea area.

7 NAVIGATION DATA (NAVDAT)

An MF radio system is designed for use in the

maritime mobile service operating in the 500 kHz

band for digital broadcasting of information relating

to maritime safety and security in the coast-to-ship

direction.

The NAVDAT system uses a time slot allocation

similar to the International Automated Alert System

known as Navigational Telex (NAVTEX), which IMO

can coordinate in the same way.

The NAVDAT system can also operate in Single

Frequency Network (SFN) mode. In this case, the

transmitters are synchronized in frequency, and the

data for transmission should be the same for all

transmitters. Thus, the digital NAVDAT 500 kHz

system provides broadcast transmission of any type

of message in the shore-to-ship direction with

encryption capability.

Any broadcast message must come from a secure

and managed source. Types of messages for

broadcast transmission include, but are not limited to,

the following particulars: 1) Navigation safety; 2)

Security Issues; 3) Data on piracy event; 4) SAR; 5)

Meteorological reports; 6) Pilot or port

communications; and 7) File transfer of the ship

traffic system.

These messages broadcast information for vessels,

groups of vessels, or in certain areas of navigation.

Besides, these messages can be addressed to a single

vessel using the Maritime Mobile Service Identity

(MMSI). The organization of the NAVDAT system is

determined by five factors that ensure the

performance of the following functions [Text. ITU-R

M.2010, 2012]:

1 System of Information and Management (SIM) –

Collects all types of information and manages this

information, creates message files to be

transmitted and creates transmission programs in

accordance with the priority of message files and

the needs of the replay;

2 Coastal Network – Provides transportation of

message files from sources to transmitters;

3 Shore Transmitter – Accepts message files from

SIM, converts message files to a signal with

Orthogonal Frequency Division Multiplexing

(OFDM) and transmits an RF signal to the antenna

for broadcast to ships;

4 Transmission Channel – Transmits radio

frequency signals at 500 kHz; and

5 Ship Receiver – Receive and demodulates an RF

signal with OFDM, restores message files and

sorts message files and makes them available to

the target equipment in accordance with the

application of the message files.

8 NORMATIVE ASPECT OF A MODERNIZATION

PLAN

Marine safety requirements are provided in chapter

XI-2 of the IMO SOLAS Convention. The Ship

Security Alert System (SSAS) does not imply the

establishment of radio communications with other

ships or coastal radio stations, and therefore, security

messages are not part of the ship-to-ship and ship-to-

shore communications. These messages are directly

addressed to the competent authorities. It follows

from the above that security messages should not be a

functional requirement for the GMDSS network,

however, chapter IV should oblige vessels to be able

to provide security-related communications and give

a clear definition “Security related communications”.

Therefore, it is proposed to add to definition IV/2 the

definition that “Security related messages” means

messages associated with updating security levels,

incidents or security threats, as well as security

information prior to entry to the port.

At present, many maritime Coastal Radio Stations

(CRS) terminals state-owned are providing public

correspondence in most cases are closed, in contrast

to the time when the GMDSS system was just in its

infancy. However, the equipment providing this type

of communication is still relevant. This type of

communication is carried out through commercial

services that are in no way associated with coastal

radio stations, and the term “Private Messages” itself

is no longer widely used. In this regard, for the

GMDSS Modernized System, it is proposed to change

the term “Private Messages” to “Other Messages”

and include new features in this definition, but not as

part of the functional requirements of the GMDSS. It

is proposed to revise the term “General Radio

Communication (GRC)” by agreeing it with the Radio

Regulations. The Proposed new definition for GRC

[NCSR 4/12, 2016] states: “General radio

communication means the exchange of official

messages, but not about distress, transmitted by

radio”.

9 CONCLUSION

Discussions on the modernization of the GMDSS

network are ongoing. The future of the GMDSS

Modernization Plan is closely connected with the

development of the e-Navigation project, and it is

important to note the role of radio systems in this

process. Undoubtedly, the data network will become

one of the most important parts of the e-Navigation

and reliable tracking systems projects. When carrying

998

out modernization of the GMDSS, it is necessary,

firstly, to identify the needs of real users, and,

secondly, to realize that the modernization of

maritime radio communications should not be

limited only by technical requirements. In addition to

the above, it is necessary to provide a sufficient

amount of a human-machine interface and human

resources, including staff training.

When upgrading the system, all the “flaws” of the

initial development and operation of the GMDSS

network should be taken into account. In addition,

the modernization process must be continuous and

open, remain modern, and meet the expected

requirements of electronic navigation. To ensure this,

a mechanism for the continuous evolution of GMDSS

should be created on a systematic basis. With this

approach to the modernization of the GMDSS, it is

very important that the integrity of the system is not

violated.

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