International Journal

on Marine Navigation

and Safety of Sea Transportation

Volume 5

Number 1

March 2011

121

1 INTRODUCTION

The beginning of the marine communications at dis-

tance born with the use of the telegraphy without

threads, the localization of a ship was based on

warnings transmitted by the sailors or automatic ma-

chines. The effectiveness of these systems was

demonstrated in the rescue services and salvage of

human lives, during more than a century. Currently

the security of a ship would be reduced, if enters its

systems don't have some able to indicate its position,

providing the necessary data with the objective to

beginning a rescue in the event of emergency or ca-

tastrophe.

In the XX century, the marine transport began to

introduce a new aid system, the Global Maritime

Distress Safety System (GMDSS), based in the au-

tomatic alarms through communications for satel-

lites and the radiobeacons use that transmit data that

help to the localization of a ship.

2 GLOBAL MARITIME DISTRESS SAFETY

SYSTEM (GMDSS)

The Global Maritime Distress Safety System

(GMDSS), it is a group of procedures of security,

devices and communication protocols designed, to

increase the security and to facilitate the sailing and

the rescue of ships in danger.

This system is regulated by the International

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

approved under the auspices of the International

Maritime Organization (IMO), dependent organism

of the UN. It is operative in the merchant ships and

of passage from 1999.

The GMDSS it is composed of satellites and ter-

restrial systems that try to carrying out the following

operations: alerts (including position), search coor-

dination and rescue, localization (positioning), pro-

vision of marine information, general communica-

tions and communications bridge to bridge.

Among the satellites systems are: INMARSAT

and COSPAS-SARSAT and in the terrestrial ones

we find: HF, MF, VHF, AND NAVTEX. The used

communication techniques are: radio, telephony, te-

New Proposal for Search and Rescue in the Sea

I. Padrón Armas

c/ Guaydil No 68 Tamarco, Tegueste, Tenerife, Espana

D. Avila Prats, E. Melón Rodríguez, I. Franquis Vera & J. Á. Rodríguez

Hernández

Dpto. CC y TT de la Navegación (ULL) C/ Padrón Albornoz s/n, S/C

ABSTRACT: Currently the security of a ship would be reduced if among its systems don't have some able to

indicate its position, providing the necessary data to try that the Rescue System begin a rescue in the event of

emergency or catastrophe. Formerly the localization of a ship was based on warnings transmitted by the sail-

ors or automatic systems. The efficiency of these systems was demonstrated in the rescue services and sal-

vage of human lives obtained along more than a century. Since final of the last century the marine transport

introduced a new aid system, the Global Maritime Distress Safety System (GMDSS), based in the automatic

alarms through communications for satellites and the radiobeacons use that transmit data that help to the lo-

calization of a ship.

In this work is sought to characterize some of the systems of satellites more diffused for the localization of aid

signs (INMARSAT, COSPAS-SARSAT), adding the project IRIDIUM for improvement of the search and

rescue, by means of the surveillance from satellites in orbit. A comparison will be established among these

systems, taking parameters like: global covering, emission of false alarms, portability and economic cost, with

the objective of determining the most effective system in case of catastrophes.

122

legraphy of direct impression and digital selective

call [1].

3 SATELLITAL SYSTEMS

When more developed it is a society, more high it is

their demand level in all the fields, especially in the

communications. The systems of communications

by satellites are the answer to this demand. Its privi-

leged location in the space and the absence of obsta-

cles with the users, do that the cellular telephony

concept, extends beyond of any impediment, alt-

hough they are not exempt of such meteorological

inconveniences as the rain, atmospheric humidity,

ice, sunspots, etc. The communications with satellite

way in the ships have supposed the world covering

for the same ones, facilitating to connect with any

telephone of the world in a quick and effective way.

The advantage is that, in all moment it is possible to

know which one it is the necessities of the ship to be

able to aid them, in the event of emergency or catas-

trophe.

3.1 COSPAS-SARSAT

This satellite system was initially developed under a

Memorandum of Understanding among Agencies of

the former USSR, USA, Canada and France, signed

in 1979.

Fig.1. COPAS-SARSAT System Overview.

The mission of the Programme is to provide accu-

rate, timely and reliable distress alert and location

data to help Search and Rescue (SAR) authorities

assist persons in distress. The objective of the Co-

spas-Sarsat System is to reduce, as far as possible,

delays in the provision of distress alerts to SAR ser-

vices, and the time required to locate a person in dis-

tress at sea or on land and provide assistance to that

person, all of which have a direct impact on the

probability of survival. To achieve this objective,

Cospas-Sarsat participants implement, maintain, co-

ordinate and operate a satellite system capable of de-

tecting distress alert transmissions from radio bea-

cons that comply with Cospas-Sarsat specifications

and performance standards, and of determining their

position anywhere on the globe (Fig 1). The distress

alert and location data is provided by Cospas-Sarsat

Participants to the responsible SAR services.

The System is available to maritime and aviation

users and to persons in distress situations. Access is

provided to all States on a non-discriminatory basis,

and is free of charge for the end-user in distress.

The System is composed of:

− distress beacons operating at 406 MHz;

− SAR payloads on satellites in low-altitude Earth

orbit and in geostationary orbit;

− ground receiving stations spread around the

world; and

− a network of Mission Control Centres (MCCs) to

distribute distress alert and location information

to SAR authorities, worldwide.

− Satellite processing of old analogue technology

beacons that transmit at 121.5 MHz ended on 1

February 2009 [2, 3].

3.2 INMARSAT

The company was originally founded in 1979 as the

International Maritime Satellite Organization (IN-

MARSAT), a not-for-profit international organiza-

tion, set up at the behest of the International Mari-

time Organization (IMO), a United Nations body,

for the purpose of establishing a satellite communi-

cations network for the maritime community. It be-

gan trading in 1982. From the beginning, the acro-

nym "INMARSAT" was used. The intent was to

create a self-financing body which would improve

safety of life at sea. The name was changed to

"International Mobile Satellite Organization" when

it began to provide services to aircraft and portable

users, but the acronym "INMARSAT", was kept.

Aside from its commercial services, INMARSAT

provides global maritime distress and safety services

(GMDSS) to ships and aircraft at no charge, as a

public service (Fig 2).

Fig.2. Inmarsat system communication.

123

Services include traditional voice calls, low-level

data tracking systems, and high-speed Internet and

other data services as well as distress and safety ser-

vices. The most recent of these provides GPRS-type

services at up to 492 kbit/s ways the Broadband

Global Area Network (BGAN) IP satellite modem

the size of a notebook computer. Other services pro-

vide mobile Integrated Services Digital Network

(ISDN) services used by the media for live reporting

on world events via videophone.

Today INMARSAT owns and operates three

global constellations of 11 satellites flying in geo-

synchronous orbit 37,786 km (22,240 statute miles)

above the Earth [4].

3.3 IRIDIUM

Iridium Communications Inc. (formerly Iridium

Satellite LLC) is a company, based in McLean, VA,

United States which operates the Iridium satellite

constellation, a system of 66 active satellites used

for worldwide voice and data communication from

hand-held satellite phones and other transceiver

units (Fig 3). The Iridium network is unique in that it

covers the whole Earth in real time, including poles,

oceans, terrestrial areas and airways.

Fig 3. Iridium System communication.

The company derives its name from the chemical

element iridium. The number of satellites projected

in the early stages of planning was 77, the atomic

number of iridium, evoking the metaphor of 77 elec-

trons orbiting the nucleus [5].

The Iridium system requires 66 active satellites in

orbit to complete its constellation and spare satellites

are kept in-orbit to serve in case of failure. Satellites

are in low-Earth orbit (LEO at a height of approxi-

mately 485 mi (781 km) and inclination of 86.4°.

Orbital velocity of the satellites is approximately

17,000 mph (27,000 km/h) (Fig 4). Satellites com-

municate with neighbouring satellites via K

band

inter-satellite links. Each satellite can have four in-

ter-satellite links: two to neighbours fore and aft in

the same orbital plane, and two to satellites in

neighbouring planes to either side. The satellites or-

bit from pole to pole with an orbit of roughly 100

minutes. This design means that there is excellent

satellite visibility and service coverage at the North

and South poles, where there are few customers. The

over-the-pole orbital design produces "seams" where

satellites in counter-rotating planes next to one an-

other are traveling in opposite directions. Cross-

seam inter-satellite link hand-offs would have to

happen very rapidly and cope with large Doppler

shifts; therefore, Iridium supports inter-satellite links

only between satellites orbiting in the same direc-

tion. [7].

Fig 4. Constellation of the Iridium System.

The satellites each contain seven

Motorola/Freescale PowerPC 603E processors run-

ning at roughly 200 MHz, connected by a custom

backplane network. One processor is dedicated to

each cross-link antenna ("HVARC"), and two pro-

cessors ("SVARC"s) are dedicated to satellite con-

trol, one being a spare. Late in the project an extra

processor ("SAC") was added to perform resource

management and phone call processing.

On the ground, Iridium’s network includes gate-

ways in Arizona and Alaska; a satellite network op-

erations center in Virginia; a technical support center

in Arizona; and four tracking, telemetry and control

(TTAC) stations in Canada, Alaska, Norway and Ar-

izona - all interconnected by advanced fiber-optic

and broadband satellite links. As with the satellite

constellation, the ground infrastructure is designed

with resiliency, permitting voice and data traffic, as

well as satellite backhaul data links, to be rerouted

as needed. The U.S. Department of Defense also has

124

its own gateway in Hawaii to support U.S. govern-

ment traffic [5].

The system is being used extensively by the U.S.

Department of Defence through the DoD gateway in

Hawaii. The DoD pays for unlimited access for up to

20,000 users [7].

The commercial gateway in Tempe, Arizona,

provides voice, data, and paging services for com-

mercial customers on a global basis. Typical cus-

tomers include maritime, aviation, government, the

petroleum industry, scientists, and frequent world

travellers.

Iridium satellites are now an essential component

of communications with remote science camps, es-

pecially the Amundsen-Scott South Pole Station. As

of December 2006, an array of twelve Iridium mo-

dems was put online, providing continuous data ser-

vices to the station for the first time [7].

Iridium is currently developing, and is expected

to launch beginning in 2015, Iridium NEXT a se-

cond-generation worldwide network of telecommu-

nications satellites, consisting of 66 satellites and six

in-orbit and nine ground spares. These satellites will

incorporate features such as data transmission which

were not emphasized in the original design. The

original plan was to begin launching new satellites

in 2014. Satellites will incorporate additional pay-

load such as cameras and sensors in collaboration

with some customers and partners. Iridium can also

be used to provide a data link to other satellites in

space, enabling command and control of other space

assets regardless of the position of ground stations

and gateways. The constellation will provide L-band

data speeds of up to 1.5 Mbps and High-speed Ka-

Band service of up to 8 Mbps [5, 6, 7].

4 IRIDIUM SYSTEM ADVANTAGES.

1 Iridium system offers a worldwide voice and

data communication from hand-held satellite

phones and other transceiver units from hand-

held satellite phones and other transceiver units,

more complete that Inmarsat system, that not

cover the poles.

2 The IRIDIUM terminals are smaller that the

beacons of the INMARSAT and COPAS-

SARSAT systems, in weight and volume, easy

to place in the harness of a lifeboat vest.

3 The cost of the communication from hand-held

satellite phones services is more economic in

the IRIDIUM system that in the INMARSAT

system.

4 The speed of answer in the Iridium systems is

bigger than the INMARSAT and COPAS-

SARSAT systems.

5 The possibility to have a terminal IRIDIUM in

the harness in the catastrophe event, would al-

low us to transmit the alarm sign, the data of

coordinated and identity of the ship and with

the voice interaction to contrast if it is a real

alarm. This would allow reduced the false

alarms that in the COSPAS-SARSAT system

are very high.

5 CONCLUSION

Today the effectiveness of Global Maritime Distress

Safety System (GMDSS) is questioned, for the bad

management of the system in catastrophes as the

Ferry Al-Salam Bocaccio 98 in the Red Sea in the

2006. It is possible that if the IRIDIUM project ded-

icates several frequencies for the transmission of da-

ta in the event of catastrophe (number of the ship,

position and catastrophe type), as well as centres of

reception of the calls to contrast that the alerts that

take place are true, It is possible that if the IRIDIUM

project dedicates several frequencies for the trans-

mission of data in the event of catastrophe (number

of the ship, position and catastrophe type), as well as

centres of reception of the calls to contrast that the

alerts that take place are true, will be an important

step to improving the security of the human life in

the sea and GMDSS would recover credibility.

REFERENCE.

[1] González Blanco, Ricardo. “Incidencia de las Nuevas

Tecnologías en la Seguridad de los Buques”. Director:

González Pino, Enrique. Universidad Politécnica de

Cataluña, Centro de Documentación del Departamento de

Ciencias e Ingeniaría Náutica, 1999.

[2] Cospas-Sarsat (International Satellite System for Search

and Rescue) “Cospas-Sarsat 1979-2009, a 30-year Success

Story” <http://www.cospas-sarsat.org/>

[3] WordLingo “Cospas-Sarsat” [en línea], 2010

<http://www.worldlingo.com/>

[4] INMARSAT “The mobile satellite company”

<http://www.inmarsat.com/>

[5] IRIDIUM Everywhere <http://www.iridium.com/>

[6] COIT (Colegio Oficial Ingenieros en Telecomunicaciones)

“Iridium: llamando al Planeta Tierra” <http://www.coit.es/>

[7] IRIDIUM. <http://es.wikipedia.org/wiki/Iridium>