basic concept of thegmdss and 9 comm functions

8/14/2019 Basic Concept of Thegmdss and 9 Comm Functions

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Basic Concept of the GMDSBasic Concept of the GMDSThe fundamental difference between the old and theThe fundamental difference between the old and the

distress system is that thedistress system is that the

new system is shornew system is shor

centred/coordinated and moves emphasis from scentred/coordinated and moves emphasis from s

ship alerting to ship to shore alerting.ship alerting to ship to shore alerting. The new sysThe new sys

quicker, simpler and, most importantly, more efficienquicker, simpler and, most importantly, more efficien

reliable than the old manual Morse Code andreliable than the old manual Morse Code and

radiotelephone alerting system. GMDSS is specificradiotelephone alerting system. GMDSS is specific

designed to automate a ships radio distress alertdesigned to automate a ships radio distress alert

function, and consequently, remove the requiremenfunction, and consequently, remove the requiremen

manual (human) watch-keeping on distress channmanual (human) watch-keeping on distress chann


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The basic concept of the system is that search and reauthorities ashore, as well as shipping in the immediavicinity of the ship in distress, will be rapidly and automalerted to a distress situation so that they can assist in

coordinated SAR operation with minimum delay. The also provides for urgency and safety communicationsthe promulgation of maritime safety information (MSI)including- navigational and meteorological warnings aforecasts, and other urgent safety information to ships

other words, every ship, fitted appropriately for GMDSable, irrespective of the area in which it operates, to pthose communication functions, which are essential fosafety of the ship itself and of other ships operating in same area.


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The Communication FunctionsThe Communication Functions1. Distress alerting Ship to shore

The Global Maritime Distress and Safety System

(GMDSS) as described in SOLAS Chapter IVdefines the first functional requirement as:

"Every ship, while at sea, shall be capable

of transmitting ship-to-shore distess alerts

by at least two independent means, each

using a different radiocommunication

service".three basic means of transmitting a distress alert:

EPIRB

Digital Selective Calling (DSC)

INMARSAT


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2. Distress alerting Shore to sh2. Distress alerting Shore to sh"Every ship, while at sea, shall be capable of receiv

shore-to-ship distress alerts"This function may be fulfilled by either of two means

direct broadcast to vessels from a shore based Resc

Co-ordination Centre (RCC) using Digital Selective c

using the MF, HF or VHF frequency bandsusing a broadcast ofMaritime Safety Information (

using either the NAVTEXservice or the SafetyNET

service.
http://../GMDSS/Pictures/NAVTEX.jpghttp://../GMDSS/Pictures/NAVTEX.jpg


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3. Distress alerting Ship to ship3. Distress alerting Ship to ship

"Every ship, while at sea, shall be capable of

transmitting and receiving ship-to-ship dist

alerts".

Transmission of ship-to-ship distress alerts can o

be accomplished by two methods:

by VHF Channel 16 (Distress, Safety and callingChannel) or VHF Channel 13 (Bridge-to-Bridge

communications channel)

by using Digital Selective Calling on eitherMF, H

VHF


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4. Search and Rescue Co-ordinating Communicatio4. Search and Rescue Co-ordinating Communicatio

"Every ship, while at sea, shall be capable of transmitting and receiving SeRescue Co-ordinating Communications".

The purpose of this requirement is to co-ordinate search and res(SAR) communications between all vessels and aircraft that minvolved in the incident.

Voice communications would normally be used, although initiallypromulgation of information through the broadcast of MaritimeInformation (MSI) may be used by a Rescue Co-ordination Ce(RCC) to ascertain which vessels are in the area of the incideare in a position to assist.

Thus any of the following methods of communication could be usTransmission/reception ofMaritime Safety Information, NAVSafetyNET

Voice communications using MF/HF orVHF orInmarsat


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5. On-Scene Communication5. On-Scene Communication"Every ship, while at sea, shall be capable of transmitting and

receiving On-Scene Communications".

The purpose of this requirement is to co-ordinate

search and rescue (SAR) and other

communications between all vessels and aircra

that may be involved at the scene of the incidenVoice communications using MF/HF orVHF wou

normally be used.


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6. Locating6. Locating"Every ship, while at sea, shall be capable of

transmitting and as required by regulation

V/12(g) and (h), receiving signals for locating".

RADAR (9GHz) for receiving

SART(Search and Rescue Radar

Transponder) for transmiting

7 / fT i i /R ti f M iti


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7.7. Transmission/Reception of MaritimTransmission/Reception of Maritim

Safety InformationSafety Information

"Every ship, while at sea, shall be capable of

transmitting and receiving maritime safetyinformation".

NAVTEX reception by terrestrial

communication

SafetyNET transmission/receptio

satellite communication


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8. General Radiocommunications8. General Radiocommunications"Every ship, while at sea, shall be capable of transmittin

receiving general radiocommunications to and from s

based radio systems or networks subject to regulatio

15(8)"

General communications may be carried out utiliz

the following systems:

Digital Selective Calling to set up a telephone

telex link on MF/HF or VHF

The Inmarsat network


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9. Bridge-to-Bridge Communicatio9. Bridge-to-Bridge Communicatio

"Every ship, while at sea, shall be capable of transmittingand receiving bridge-to-bridge communications"

Ships would normally use VHF communications to carry out tfunction. The normal use of this function would be for portoperations and pilotage. Occasionally, for longer range MForInmarsat could be used. The setting up of communicatio

usingMF/HF would be via Digital Selective Calling.
http://www.inmarsat.com/Maritimesafety/mfhf.htmhttp://www.inmarsat.com/Maritimesafety/mfhf.htm

basic concept of thegmdss and 9 comm functions

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