259

1 INTRODUCTION

The focus of maritime communications and GMDSS

networks these days is concentrated towards satellite

communications and IP networking. Many things

have changed from even a few decades ago, when

radiotelegraphy and radio telex were main method of

ship to shore and vice versa radiocommunication

systems, so oceangoing ships are now effectively

expanding computer LAN over satellite networks.

However, VHF, HMF and HF radio communication

systems continue to provide huge support for

upgrading the GMDS network.

Of course, the driver for all these changes in

distress Search and Ressque (SAR) operations was the

establishment of the GMDSS network in the early

1990’s, which still uses VHF and HF Digital Selective

Calls (DSC), VHF radiocommunication systems and

NAVTEX transmissions. After the GMDSS operator

onboard ships sends an DSC alert, then it switches to

the radiotelephone distress and safety channels and

conducts onscene communications with other ships,

SAR forces and shore stations. The problem is that

these channels are often plagued by interference and

that some new and most reliable solutions should be

proposed. Here will be shortly introduced new VHF

and MF radio systems able to improve radio

Communication, Navigation and Surveillance (CNS)

requirements for the GMDSS network [01, 02, 03].

Alternative Maritime Radio Solutions for Enhanced

GMDSS Network

.S. Ilcev

University of Johannesburg (UJ)

, Johannesburg, South Africa

ABSTRACT: This paper introduces novel alternative maritime radio solutions for the improved Global

Maritime Distress and Safety System (GMDSS) network and equipment within the Very High Frequency (VHF),

Medium Frequency (MF) and High Frequency (HF) Ship Radio Station (SRS) terminals. Since its foundiing in

1959, International Maritime Organization (IMO) and its member states, in close co-operation with the

International Telecommunication Union (ITU) and other international organizations, notably the World

Meteorological Organization (WMO), the International Hydrographic Organization (IHO), the International

Mobile Satellite Organization (IMSO) and the Cospas-Sarsat partners, have striven to improve maritime distress

and safety radiocommunications, as well as general radiocommunications for operational and personal

purposes. This paper also reviews concept of the GMDSS network, an overview of new propsed by author

maritime VHF Data Link (VDL), maritime Radio Automatic Dependent Surveillance-Broadcast (RADS-B), an

maritime GNSS Augmentation VDL-Broadcast (GAVDL-B). In addition, the type of the current radio Maritime

VHF Data Exchange System (VDES), Maritime MF-band Navigational Telex (NAVTEX), and Maritime MF/HF-

band Navigation Data (NAVDAT) are also described in this paper.

http://www.transnav.eu

the

International Journal

on Marine Navigation

and Safety of Sea Transportation

Volu

me 16

Number 2

June 2022

DOI: 10.12716/1001.16.02.08

260

2 MARITIME VHF DATA LINK (VDL)

The aim of this section is to present a new proposed

marine VHF Data Link (VDL) similar to aeronautical

VDL, which can be applied in the future for the CNS

service within the GMDSS network in the Sea Area

A1. The new VDL service has to improve GMDSS

solutions in coastal navigation, inland waters,

approaching to anchorage and inside of the harbors as

new solution with 3 main objectives:

1. To provide a more reliable and effective ships

communications system based on efficient and

higher rate digital transmission over VHF radio

including International Ship and Port Facility

Security Code (ISPS) system in harbors;

2. To improve R-AIS basic functions for ships

collision avoidance; and

3. To enhance GMDSS network, Ship Traffic Control

(STC) and Ship Traffic Management (STM)

through the VDL network, together with the

proposed RADS-B network.

Figure 1. Maritime VDL Radio System for Enhanced

GMDSS Network –Source: Ilcev

The ship's VDL system will be similar to R-AIS

with the task of improving its capabilities and

functionality, the configuration of which is shown in

Figure 1. A major improvement of R-AIS requires the

installation of VDL transponders onboard ships for

improved STC and CTC in coastal waters,

approaching anchorages and seaports. In the same

way, similar VDL installations will be able to control

the movement of land vehicles and rails within

seaports. Both ships and vehicles transporters can be

integrated with GNSS receivers that can receive

navigation signals from GPS or GLONASS satellites

and resend them via VHF Coast Radio Stations (CRS)

terminals to STC and STM operational centres.

Received Position, Velocity and Time (PVT) data

from ships and vehicles within VHF coverage will be

processed and displayed on radar like a VDL display

unit. In the opposite direction, the ship traffic

controller may send PVT to all ships outside seaports

and in particular to all ships and land vehicles within

the seaport, and manage their movement in a safer

manner [04, 05, 06, 07, 08].

3 MARITIME RADIO AUTOMATIC DEPENDENT

SURVEILLANCE-BROADCAST (RADS-B)

The Radio Automatic Dependent Surveillance-

Broadcast (RADS-B) communication mode has been

developed for aeronautical applications, but can also

be used for maritime applications, the configuration

of which is illustrated in Figure 2. This system can

uses radio transmissions from ships, approximately

once in a while, to provide PVT and other data that

have been detected and captured by onboard ships

sensors, such as not-augmented Global Navigation

Satellite System (GNSS) receiver (GPS or GLONASS),

Automatic Radar Plotting Aid (ARPA) or

Gyrocompass.

The RADS-B VHF CRS terminal uses a non-

rotating omnidirectional radio antenna to receive VDL

messages transmitted from ships in a certain ocean

area. The maritime RADS-B network has been

proposed as a multiple use surveillance technique for

harbour terminals, approaching to anchorage, sea

passages and coastal waters in range of VHF CRS

terminals and is also applicable to STC, STM and

ship-to-ships data transmitting OUT and receiving IN

surveillance, known as an Internship RADS-B for

enhanced collision avoidance.

The RADS-B transmission is “line of sight” based

surveillance and requires CRS terminals to receive

data and transmit to STC and STM operational

centres. A single CRS can provide coverage out to

approximately 250 Nm for coastal enroute, terminals

and seaport area surface surveillance. This RADS-B

communication network can be integrated with

Ground Surveillance Radar (GSR) installations and

provide additional surveillance capabilities. In ordet

to improve ships surveillance and traffic control in the

seaport area, this new system will require a special

RADS-B transceivers integrated with GNSS receivers

installed onboard ships and land vehicles [02, 04, 09,

10, 11].

Figure 2. Maritime RADS-B System for Enhanced GMDSS

Network –Source: Ilcev

261

4 MARITIME GNSS AUGMENTATION VDL-

BROADCAST (GAVDL-B)

The GNSS-1 network is integral part of all

applications where mobile CNS solutions play an

important role in the development of modern

configurations for enhanced STC and STM, and in

particular for improved GMDSS shipborne facilities.

In the GNSS-1 satellite network are integrated the US

GPS and the Russian GLONASS, while the Chinese

BeiDou or Compass and the European Galileo are

included in the GMSS-2 network. The GNSS network

provides standardized PVT information via VDL to

oceangoing ships for more precise navigation and

enhanced collision avoidance in global scene, which

scheme is shown in Figure 3. The VDL system in the