MV Estonia, Baltic Sea 28 September 1994 - Pacific … What’s your phone number? Unique 9 digit number. MMSI is issued by AMSA. MMSI programmed into the radio(s). MMSI is always

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MV Estonia, Baltic Sea28 September 1994

Digital Selective Calling 1

989 Passengers on board


137 survived

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Digital Selective Calling

Andy Shipp


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Kinetic Energy


HMS Fife

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GMDSS

Prior to 1988, the number and type of radio systems was based on tonnage.

In 1988, GMDSS was incorporated in to the SOLAS Convention of 1974.

Post 1988, the number and type of radio systems was based on Sea Area.


GMDSS


Global Maritime Distress & Safety System

Integrated communication system developed by the International Maritime Organisation (IMO).

Designed to enhance ship-to-shore, ship-to-ship and shore-to-ship communications and provide rapid, automated distress alerting, with positional information.

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GMDSS


GMDSS applies to vessels subject to the SOLAS convention. That is,

• Vessels over 300 tonnes on international voyages.

• Cargo ships over 500 tonnes.

• All passenger vessels with more than 12 passengers.

• Vessels as required by Flag State.

GMDSS Sea Areas


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GMDSS Sea Areas


A1 Within coverage range of a VHF Coast Station with DSC capability.

30-40nm

A2 Within coverage range of an MF Coast Station with DSC capability, excluding Area A1.

up to 180nm

A3 Within coverage footprint of an Inmarsat GEO Satellite, excluding Areas A1 & A2.

70N to 70S

A4 Area outside A1, A2 & A3.

UK Sea Area Map


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GMDSS Segments

� Rescue Coordination Centres.

� INMARSAT & Earth Stations.

� Cospas-Sarsat network & LUTs

� HF & NBDP network.

� EPIRBs & SARTs.

� NAVTEX.

� Digital Selective Calling (DSC).


GMDSS


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Listening Watch?


On GMDSS ships, the requirement for a listening watch ended,

• in 1999 on 2182MHz.

• in 2005 on VHF?

Digital Selective Calling (DSC) may be the only method of establishing communications.

Digital Selective Calling

� Semi-automatic system used for establishing initial contact between stations.

� Once contact has been established, standard radio telephony procedures are used.

� DSC may be used for distress, urgency, safety or routine calls.


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DSC Alerts

� Information transmitted by DSC is known as a DSC Alert.

� MF/HF - 7s at 100 bps1700Hz ±85Hz.

� VHF - 600ms at 1200 bps1700Hz ±400Hz

� DSC Alerts are transmitted on reserved channels on each band.


DSC Frequencies


* Monitored by Wiluna & Charleville.

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VMW & VMC


DSC Frequencies

� MF/HF DSC frequencies are reserved for Distress, Urgency and Safety messages.

� Only VHF channel 70 may be used for Routine messages.

� Unless specified in the DSC Alert, the associated radiotelephony channel should follow the distress and calling frequency.


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DSC Frequencies

� Use of DSC frequencies for voice calling is prohibited.

� Australian Maritime Communications Stations monitor HF DSC frequencies only.

� MF and VHF DSC frequencies are not monitored.


DSC Radio

What makes a DSC radio different?

1. It knows who it is.

2. It knows where it is.


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DSC Radio Installation


DSC Radio


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DSC Classes

Function Class A Class D

Distress � �

Distress Relay �

All ships Urgency � �

All ships Safety � �

Individual � �

Group �

Geographic Area �

Telephone �


What’s in a DSC Alert?

� Dot Pattern

� Phasing Signal

� Format specifier


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Format Specifier

Distress

All ships

Individual station

Groups of stations

Stations in Geographical Area

Automatic phone call



� Dot Pattern

� Phasing Signal

� Format Specifier

� Address (MMSI or Geographic Area)

� Category


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Category

Distress

Urgency

Safety

Routine


Distress Urgency & Safety

Distress Vessel or person sending is in grave and immediate danger and requires immediate assistance.

Urgency Very urgent message concerning the safety of a vessel, aircraft or person.

Safety A message concerning an important navigational or weather forecast,

Routine Chitchat


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� Dot Pattern

� Phasing Signal



� Category

� Self-ID (MMSI)

� Messages


Messages

� A message may be added manually to the DSC Alert.

� A received message will be displayed on the receiving radio.

� DSC Alert will include ship’s position if GPS is connected.


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Messages

Nature of DistressFire, Flooding, Collision,

Grounding, Sinking, MOB

Vessel Position & Time UTC Time for Position

Working Frequency 72, 73, 77, etc.

Relay & Acknowledge

RT or NBDP

Geographical Area

Telecommands Test, Position, Polling

Phone number



� Dot Pattern

� Phasing Signal



� Category

� Self-ID (MMSI)

� Messages

� EOS/Error Check


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What’s your phone number?

� Unique 9 digit number.

� MMSI is issued by AMSA.

� MMSI programmed into the radio(s).

� MMSI is always sent.

� DSC will likely eliminate hoax calls.


MMSI - Maritime Mobile Service Identity

MMSI

• Electronic equivalent to call sign.

- Kinetic Energy

- VHS6124

- MMSI 503 018 400

• First 3 numbers identify countryMaritime Identification Digits (MID)

Australia’s MID = 503UK = 232, 233, 234 & 235

• No MMSI � No DSC Radio.


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MMSI

Ship station 503123450

Group of ships 050312345

Coast Station 005030001

Aid to Navigation 995031234

Craft associated with parent ship 985031234

Aircraft using MMSI for SAR 111503123


Inadvertent Distress Alert

� Immediately switch off DSC transceiver to cancel repeats.

� Switch transceiver back on.

� Select radiotelephony channel associated with DSC channel.

� Broadcast an “all stations” message giving vessel name, call sign and MMSI, and cancel distress alert.

� Repeat for all channels.


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Uses of DSC

� Distress traffic.

� Free up VHF channel 16.

� Vessel group when cruising.

� Position polling.

� MOB location.


VPIRB

� When activated, transmits a DSC distress message on VHF 70, and

� a synthesised voice distress message on VHF 16.

� Both include GPS position of MOB.


VHF Position Indicating Radio Beacon

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VPIRBs


VPIRB Advantages

� Message sent to MOB’s vessel.

� DSC radio provides the MOB alarm.

� Message also sent to vessels in immediate area.

� MOB position is more accurate than an EPIRB.

� Multiple MOBs do not cause problems.

� Avoids RCC Australia in the loop.


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VPIRB Disadvantages

� Range limited to 10nm.

� Reduced use if boat sinks.

� RCC Australia not in the loop.


Search Areas


406 EPIRB 406 GPIRB

VPIRB

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Problems with DSC

� No telephone directory.

� Getting the concept across.

� Radio compatibility.


Teaching DSC

Students are usually having a problem with radio full stop.

Adding DSC adds a level of complexity.


Documents

MV Estonia, Baltic Sea 28 September 1994 - Pacific … What’s your phone number? Unique 9 digit number. MMSI is issued by AMSA. MMSI programmed into the radio(s). MMSI is always