Digital Selective Calling-DSC During Disasters or Emergencies

Digital Selective Calling (DSC) is a vital communication technology used in maritime safety and operations. This provides an overview of DSC, covering its purpose, core concepts, call formats, and operational procedures.

We’ll also explore scenarios where a distress alert originates from a source not in immediate danger and more.

Purpose of DSC

Digital Selective Calling provides automated access to coast stations and ship.

The message information is stored in the receiver and can be displayed or printed out following receipt. Four levels of priority-distress, urgency, safety and routine- are available for DSC calls. At the coast station, ship-to-shore distress calls receive priority handling and are routed to the nearest Rescue Co-ordination Centre (RCC). On board ship, DSC receivers sound an alarm when a distress call is received.

DSC Concept

DSC is technique of transmitting digital codes which allow suitably equipped stations to:

(a) Transmit and receive distress alerts.

(b) Transmit and receive distress alert acknowledgments.

(c) Relay distress alerts.

(d) Announce urgency and safety calls.

(e) Initiate routine priority calls and set up working channels for subsequent general communications on R/T or telex.

The detailed DSC procedures are contained in ITU-R Recommendation 541 (always refer to the latest version).

DSC channels have been allocated in the 2, 4, 6, 8, 12 and MHz MF/HF bands and on VHF channel 70.

DSC Call Format

All DSC calls automatically include phasing signals, error-checking signals and the identity (MMSI number)of the calling station. The protocol includes an initial dot pattern which is used to alert scanning receivers that a DSC call is imminent. Other information can be added, either manually or automatically. The actual information added is dependent upon the purpose of the call.

The DSC call is set up by entering information, using the command menu of the DSC controller that that is attached to, or incorporated into, the transmitter.

MMSI Numbers

Each ship station has its own unique nine-digit Maritime Service Identity (MMSI) which is included automatically in each call. Included in the MMSI number are the Maritime Identification Digits (MID) which identify the country licensing/controlling the station.

Three types of MMSI numbers are in common use to identify individual ships, groups of ships and coast stations.

Examples, using the MID 264 (Romania), are:

1. Ship stations – 264001021;
2. Group of ships – 026401143 (1 leading zero);
3. Coast station – 002640018 (2 leading zeroes).

Other codes make provision for “All Ships” calls or calls to ships in particular geographical areas.

The MMSI number is used to form the international subscriber number of Inmarsat-B, -C and -M ship earth stations. Because of the way the MMSI is translated to a sattelite terminal number, suitable MMSIs are limited to those with three trailing zeros.

To avoid exhausting the supply of MID numbers too rapidly, MMSI numbers with three trailing zeroes should only be assigned to ships which expect to have automatic acces to the public switched telephone network (PSTN) on a world wide basis or which expect to use Inmarsat-B, -C and -M.

In practice, most Administrations assign MMSI numbers with three trailing zeroes only to zeroes only to vessels subject to the SOLAS Convention.

Other ships which require acces to such networks on a national or regional level are assigned MMSIs with only one or two trailing zeros.

Operational procedures

On the MF and HF bands, one frequency in each band is allocated for distress, urgency and safety purposes.

These frequencies are programed into the DSC equipment for selection when neccesary; also in each band there are national and international call and reply frequencies for routine calling. Whenever possible, national channels should be used for routine calls; e. g., on MF, 2187,5 kHz is used only for distress/safety 2189,5 kHz is used for internationally for ship/ship calls and shore/ship calls.

On the VHF band, channel 70 is used for distress/safety as well as routine calling. In the case of a routine “All Ships” call the power output should not exceed 1 W. An example situation would be to contact a nearby ship. Some DSC installations have provision to reduce the power level from 25 W to 1 W automatically. The actual band chosen will depend upon the distance involved. A list of DSC frequencies is given in section 18 and is usually to be found in manufacturers’manuals.

General Calling Procedures

Routine calls should be made once on a single frequency or channel.

Coast stations may, however, transmit a second call within 45 seconds if no acknowledgement has been received. If the call is still not acknowledged, the coast station should normally wait at least another 30 minutes before repeating the call attempt on the same frequency, or 5 minutes on another calling frequency.

Ship stations should not repeat a call attempt to a coast station until after an interval of at least 5 minutes when using manual procedures. In the case of ship stations using the semi-automatic/automatic DSC option, the minimum interval for the first repeat call is 5 seconds on VHF or 25 seconds on MF/HF. Alternative frequencies may be used for the repeat call attempt, if appropriate. The ship station call may be repeated again, but not until at least a further 15 minutes have elapsed.

To call a coast station or another ship by DSC in order to initiate routine/bussiness communications:

1. tune the transceiver to the appropriate DSC channel/frequency for the call;
2. set up the ship station DSC controller using the following general procedure (see manufacturers’manuals for specific guidance):
   • select the format for calling a specific station;
   • enter address (identification) – MMSI of called station;
   • select category of the call – routine or ship’s business (ship station MMSI is entered automatically);
   • select type of subsequent communication – R/T or NBDP;
   • enter proposed working channel information if calling another ship (no proposal is normally made when calling a coast station since it is the responsibility the called coast station to indicate a vacant working channel in its acknowledgement);
   • elect end-of-sequence signal – usualy the signal RQ, which means that a mandatory acknowledgement is required, when calling a specific coast station or ship station (the called station terminates its acknowledgement with the signal BQ);
   • press “Call“;
   • routine DSC messages should be acknowledged using DSC either on the same frequency or on the appropriate paired frequency, either manually (within 4^1/2minutes) or automatically.

If it is not possible to use the working channels suggested in the call, this should be indicated in the acknowledgement. If no channel is mentioned, as would normally be case when calling a coast station, suitable frequencies or chanels should be proposed in acknowledgement.

Following agreement on, and transfer to, the working frequencies/channels the called station prepares to receive the traffic.

Geographical Area Call

To address a call to a specific geographical area, use the following general procedure (see manufacturer’s manuals for specific guidance):

• select menu function “G. area”;
• enter latitude of north-west corner of area;
• enter latitude range;
• enter longitude of north-west corner of area;
• enter longitude range.

For example, make the entry :

N55 05 W003 02

In order to address the area shown below:

DSC Ship-Shore Link Call Automatic/Semi-automatic Service

In some countries, DSC can be used to obtain an automatic telephone call through suitably equiped coast stations. The initial DSC call should take place on a general DSC calling frequency or channel 70 VHF.

Read also: GMDSS carriage requirements and basic provisions

The DSC message format is used to set up an automatic connection into the PSTN and select appropriate public correspondance working channels for the subsequent telephone traffic. The required subscriber number is included in the initial call to the coast station and the coast station replay indicates the working channels to be used.

To access the automatic/semi-automatic facilities provided at the coast station:

1. tune the transceiver to the appropriate DSC channe/frequency for the call;
2. set up the ship station DSC controller, using the following general procedure (see manufacturers’ manuals for specific guidance):
   • select format specifier – automatic/semi-automatic service;
   • enter address (identification) – MMSI of required coast station;
   • select category – routine;
   • (ship station MMSI is entered automatically);
   • select first telecommand – J3E on MF, F3E/G3E duplex or F3E/G3E simplex on VHF, and second telecommand as appropriate;
   • enter called subscriber number (e. g., telephone number);
   • select end-of.sequence signal RQ;
   • press “Call“;

The coast station will then acknowledge by DSC. The call will be repeated automatically if an error-free acknowledgement is not received from the coast station within 5 seconds on VHF, or 25 seconds on MF/HF. Further repetitions to the same coast station should only be initiated by manual control, and should be delayed for at least another 15 minutes (see section “General Calling Procedures” above).

If working channels are free, the coast station equipment will also instruct the ship station DSC controller to commence operations on the working channels selected by the coast station. The coast station equipment will then dial the subscriber number and complete the telephone connection with the ship station.

If the coast station send the “unable to comply” signal then, depending on the installed coast station facilities, the delay may last no longer than necessary for the problem (e. g., traffic queues or subscriber line busy) to clear. The fully automated from of the service has provision for repeated connection trials by the coast station for up to 15 minutes.

However, if the call cannot complete in 15 minutes, or the problem is not straightforward then the call attempt will fail.

In the event of a failed call, another attempt will have to be initiated by the ship station but not until at least 15^1/2 minutes have elapsed since the previous attempt.

DSC Testing

DSC equipment has a in-built test facility which should be used daily but without radiating signals.

A weekly live test should also be carried out by calling a suitable coast station with the indication that it is a test call. The call must be clearly identified as a test transmission and the test frequency/channel should always be monitored to ensure that it is free before the test commences.

N. B. Equipment tests on the exclusive DSC distress and safety calling frequencies be avided using other methods as far as possible. In any event, live test transmissions on the VHF DSC calling channel (channel 70) are NOT permitted.

If general-purpose DSC calling facilities are not available through the nearby coast station, then an MF/HF DSC distress and safety calling frequency may be used for the test; the call would be classed as a “safety” call in these circumstances.

To send a test call to a coast station by DSC:

1. tune the transceiver to the appropriate DSC channel/frequency for the call;
2. set up the ship station DSC controller, using the following general procedure (see manufacturers’manuals for specific guidance):
   • select “Test“;
   • select “TX Test“;
   • enter MMSI of coast station;
   • press “Call“;
   • wait for acknowledgement by coast station.

The coast station will acknowledge the DSC test call but no further communication will normally take place.

DSC Distress Alerting Procedures

DSC Distress/Safety Frequencies

DSC alerts would normally be sent on the following frequencies or channels:

• 2187,5 kHz;
• 4207,5 kHz;
• 6312 kHz;
• 8414,5 kHz;
• 8414,5 kHz;
• 16804,5 kHz;
• channel 70 (156,525 MHz).

Note that channel 70 (156,525 MHz) may also be used for general calling, whereas the other DSC distress and safety frequencies may only be used for DSC distress calls and announcing DSC urgency and safety messages.

DSC Distress Alerting

On DSC, two types of distress alert call attempts exist:

(a) A single-frequency call attempt; where the alert is send on one frequency or channel.

(b) A multi-frequency call attempt; where up to six consecutive alert calls can be sent once on each of the six DSC frequencies on MF and HF, i. e., 2, 8, 4, 6, 12 and 16 MHz.

The DSC message format identifies the station in distress, provides its last recorded position and, if entered, the nature of the distress.

Sea Area Considerations

In sea area A1, channel 70 would be used in the first instance to transmit a distress alert. In sea area A2, 2187,5 kHz and channel 70 could be used. In sea areas A3 and A4, 8414,5 kHz would be used in the first instance or a multi-frequency call attempt should be used; 2187,5 kHz would then be used to alert ships in the vicinity.

Note: Some makes of equipment cannot perform multi-frequency calls; instead, each frequency has to be selected manually in turn.

The DSC Distress Alert Call

The DSC distress alert contains the following informations:

In a basic distress alert only the identification, position/time and words “undersignated distress” are transmitted. The distress alert is automatically repeated every 3^1/2 to 4^1/2minutes at random 1 unless a DSC acknowledgement is received or the function is manually switched off.

On receipt of a DSC distress acknowledgement, the ship in distress shall commence the distress on the appropriate R/T or NBDP distress traffic frequency as follows:

Watchkeeping on DSC Frequencies

Every ship at sea shall maintain a continuous DSC watch as appropriate to the sea area in which the ship is salling. The DSC watchkeeping frequencies are:

(a) channel 70;

(b) 2187,5 kHz;

(c) 8414,5 kHz and other HF frequency, selected according to the time of day, the season of the year and the distance from appropriate coast stations.

Those coast stations maintaining a continuous watch on the DSC distress and safety frequencies are listed in the GMDSS Master Plan, the ITU List of Coast Stations and in various national publications, e. g., the ALRS Vol. 5.

Preparations for Handling Distress Traffic

When a DSC alert is received, a display or printout is produced giving all relevant details. Also, an Alarm the operator. DSC distress alerts are implicitly addressed to “All Stations”.

Upon receiving a DSC distress alert, all stations should cease all transmissions, monitor the DSC distress and safety frequency on which the call was received and set watch on the R/T and/or NBDP distress and safety traffic frequencies in the same band. The DSC distress alert contains information under “subsequent communications” which indicates whether R/T or NBDP is to be used for subsequent distress communications.

Acknowledgement and Relay of a DSC Distress Alert by Coast Stations and RCCs

On receiving a DSC distress alert, the coast station or coast earth station communicates the information as soon as possible to the appropriate RCC. The distress alert has then to be acknowledged as soon as possible by the coast station or by the RCC via a coast station or an appropriate coast earth station. A coast station receiving a distress alert on an MF or HF DSC distress calling frequency should acknowledge in a target time of 1 minute and should not take longer that 23/4 minutes. A VHF DSC distress alert should be acknowledged as soon as posible.

A coast station acknowledging a DSC distress alert shall acknowledge on the same DSC distress calling frequency or channel on which the call was received.

The acknowledgement by DSC should be addressed to “All ships” and include the identification of the station in distress using the following message format:

The primary role of the shore-based rescue co-ordination infrastructure in the GMDSS also requires that the coast station or RCC which receives a distress alert shall initiate the transmission of a shore-to-ship distress alert relay when the method of receipt warrants a broadcast alert to shipping or when the circumstances of the distress incident indicate that further help is necessary.

The shore-to-ship distress relay must contain the identification of the station in distress, its position and all other information that might assist rescue operations.

The distress alert relay by DSC is addressed, as appropriate, to all ships, to selected group of ships, to a geographical area or to a specific ship, and transmitted using the following format:

Note: Whatever means of transmission are used,the distress alert relay must indicate clearly that the transmitting station is not itself in distress.

The purpose of shore-to-ship distress alert by a coast station is to alert all ships in the vicinity of the distress incident. Although VHF and MF DSC distress alerts should, of course, be received directly by GMDSS ship in the vicinity, the original distress signal would be missed if sent on a non-watchkeeping frequency or by some other means, e. g., by some Inmarsat, an EPIRB or by visual signals.

Acknowledgement and Relay of a DCS Distress Alert by Ship Stations

Ship stations which receive a DSC distress alert must prepare to acknowledge or relay the distress alert according to the progress of events immediately following receipt of the distress alert.

In Sea areas A1 and A2, coast stations are expected to acknowledge receipt of a DSC distress alert in the first instance. Ship should therefore acknowledge after the coast station using R/T on the R/T distress and safety traffic frequency in the same bands as the distress and safety calling frequency on which the original distress alert or the shore-to-ship distress alert relay was received.

The acknowledge should use the following format:

However, if NBDP operation was specified for subsequent communications in the distress alert, the acknowledgement using the associated NBDP distress and safety traffic frequency using the following format:

If no acknowledgement from a coast station is received within 3 minutes, still acknowledge to the station in distress on R/T. However, if there is no reply from the station in distress, it will be necessary to send a DSC ackwnowledgement on the same distress and safety frequency on which the distress alert was received. The nearest coast station must then be informed by any suitable communication means or by sending a distress alert relay.

The same action must also be taken in the event that the DSC distress alert is repeated. DSC distress alerts are automatically repeated after an interval of 3^1/2 to 4^1/2minutes until cancelled by the reception of a DSC distress alert acknowledgement. The repeat of the DSC distress alert means the NO DSC acknowledgement by a coast station was received by the ship in distress. Making the acknowledgement via DSC will halt the transmission of further DSC distress alert signals from the ship in distress.

It will be interesting: Basic Concepts of the GMDSS

Such a situation could occur, for example, if a VHF or MF DSC distress alert was transmitted in sea area A3 where the most appropriate form of distress alert, acknowledgement and shore-to-ship distress alert alert relay would normally be via satellite (see articles “Empowering Global Communication with INMARSAT Satellites in shippingINMARSAT Satellites” and “Informed for Safe Navigation at Sea with Critical Maritime InformationMaritime Safety Information (MSI)” regarding Inmarsat systems and promulgation of Maritime Safety Information).

In sea areas A4, special care is needed to avoid making spurious distress alert relays or cancelling the distress alert prematurely by sending a DSC acknowledgement.

Note that, because of the possibility of HF transmission being received at some locations but not at others (being in the skip zone, for example – see article Radio Wave Propagation – How it Works in the Shipping Industry“Exploring Radio Paths, Spectrum, and Propagation Mechanisms”), it should not be assumed either that a particular coast station has also received the distress alert or that the lack of acknowledgement implies that none was sent.

A ship station receiving an HF distress alert should therefore NOT acknowledge but set watch on the HF R/T (or NBDP, if indicated in the distress alert) distress and safety traffic frequencies associated with the DSC distress and safety calling frequency on which the distress alert was received. If no acknowledgement is received within 5 minutes then the distress alert should be relayed by any suitable means to an appropriate coast station or coast earth station.

In the event that it is deemed necessary to send a DSC distress alert relay on HF, transmissions should be made on one band at a a time and communications established with any responding ships before repeating the DSC distress alert relay on other band. This procedure is necessary to avoid causing confusion on other ships as to which band will be used for subsequent distress traffic.

A ship station which transmits a distress alert acknowledgement or a distress alert relay on a DSC distress and safety calling frequency shall use the same message format as given above for the transmission of a distress alert acknowledgement or relay by a coast station using DSC.

On some equipment, it is possible to select “Relay” after the DSC distress alert message has been displayed. In this case, the operator has to determine where best to address the distress relay and frequencies to use; the original distress message is then automatically included in the relay.

Note: NEVER, UNDER ANY CIRCUMSTANCES, ATEMPT TO USE THE DSC EQUIPMENT TO RELAY A RELAYED DISTRESS ALERT. SUCH ACTION CAN INITIATE A CHAIN OF MISLEADING RELAYS AND RESPONSES TO SEVERAL RCCs.

On other equipment, it will be necessary to make a manual relay, where all of the relavant details about the incident have to be entered by the operator.

A single-frequency or a multi-frequency call attempt can be used for a relay.

Transmission of a Distress Alert by a Station Not Itself in Distress

The circumstances in which a ship station should transmit a distress alert relay in response to distress alert which does not appear to have been to received and acted upon by a coast station have been covered above.

In other cases also, a ship station may have a duty to initiate a distress alert even though not itself in distress. In particular, a ship station which learns that a mobile unit is in distress is obliged to initiate and transmit a distress relay in any of the following cases:

• when the mobile unit in distress is unable to send a distress alert itself;
• when the master or other person responsible for the ship not in distress considers that further help is necessary.

The message format to be used in these circumstances is the same as described above for the transmission of a DSC distress alert relay.

Note: Again, it must be absolutely clear that the station transmitting the distress alert relay is not itself in distress.

Acknowledgement of a DSC Distress Alert Relay Received from Coast Stations.

Ship stations which receive a DSC distress alert relay call that is transmitted by a coast station should acknowledge receipt of the call using R/T on the R/T distress and safety traffic frequency in the same band as the distress and safety calling frequency on which the shore-to-ship distress alert relay was received.

The acknowledgement should use the following format:

VHF

1. Switch off the transmitter immediately if the false alert is detected during transmission.
2. Switch equipment on and set to channel 16.
3. Make broadcast to “All stations“, giving the ship’s name, call sign and MMSI number, and cancel the false distress alert.

Example:

MF

1. Switch off the transmitter immediately if the false alert is detected during transmission.
2. Switch equipment on and set to 2182 kHz.
3. Make broadcast to ”All stations”, giving the ship’s name, call sign and MMSI number, and cancel the false distress alert.

Example:

HF

Use the same procedure as for MF, but the alert must be cancelled on all of the frequency bands on which the alert was transmitted. The transmitter should therefore be tuned consecutively to the radiotelephone distress frequencies in the 4, 6, 8, 12 and 16 MHz bands, as necessary.

N. B. AVOID SENDING FALSE ALERTS! THE DSC DISTRESS ALERT WILL BE RECEIVED AT GREATER DISTANCES THAN THE CANCELATTION BY THE WYDER BANDWIDTH RADIOTELEPHONE TRANSMISSION

EXAMPLE SITUATIONS (1.25):

1. Receive DSC distress alert on channel 70 or 2187,5 kHZ in sea areas A1 or A2.

Action:

• Tune VHF transceiver to channel 16 and MF transceiver to 2182 kHz.
• Log information and inform the master.
• Wait for up to 3 minutes for a coast station to acknowledge by DSC on Channel 70 or 2187,5 kHz.
• Acknowledge by R/T on channel 16 or 2187,5 kHz, as appropriate.

2. Receive DSC distress alert on channel 70 or 2187,5 kHZ in sea areas A3 or A4.

Action:

• Tune VHFVHF transceiver to channel 16 and MF transceiver to 2182 kHZ.
• Log information and inform the master.
• Acknowledge by R/T on channel 16 or 2182 kHz, as appropriate.
• If no coast station acknowledgement or shore-to-ship distress alert relay is received and there is no reply to the R/T acknowledgement in the above cases, that acknowledge the distress alert using DSC on the same frequency or channel as that upon which the alert was received. (This will stop the equipment on the vessel in distress from continuing to transmit the distress alert). Then make a distress alert relay to the most appropriate coast station or coast earth station by any means at your disposal.

3. Receive DSC distress alert on an HF distress and safety calling frequency.

Action:

• Do not make immediate acknowledgement!
• Tune to the HF R/T distress and safety traffic frequency in the same band as the distress alert was received.
• Log information and inform the master.
• If no coast station acknowledgement or shore-to-ship distress alert relay is received within 3 minutes, or if further DSC distress alerts are received from the vessel in distress, then relay the distress alert to the most appropriate coast station or coast earth station by any means at your disposal.

DSC Urgency and Safety Procedures

DSC Procedures for Urgency and Safety Calls

DSC on the distress and safety calling frequencies be used by may coast stations and ship stations to announce the impending transmission of urgency, vital navigational or safety messages by R/T or NBDP. The DSC distress and safety frequencies 2187,5 kHz on MF and 156,525 MHz/channel 70 on VHF are the most likely to be used to announce urgency or safety messages. If appropriate, HF DSC distress and safety frequencies may be used.

To transmit the actual message, ship stations should use the R/T or NBDP distress and safety traffic frequencies in the same band in which the DSC announcement was transmitted. Coast stations may use a working channel to transmit a long safety message when using MF or VHF, but would normally use a distress and safety traffic frequency for urgency messages.

Care should be taken to avoid overloading the DSC distress and safety frequencies, and coast stations should not use DSC to announce transmissions which take place at scheduled times.

N. B. Urgency messages concern the safety of a ship, aircraft, vehicle or person. Safety messages concern important meteorological or navigational information.

The DSC call may be addressed to “All Ships” or to individual stations and will indicate which frequency and method, i. e., R/T or NBDP, is to be used to send the subsequent message. The urgency or safety message may be sent on the distress and safety traffic frequency or channel in the same band in which the DSC announcement call was sent, providing that this does not obstruct more important communications or conflict with the silence periods (see article Marine Radio Receivers and Transmitter (frequency ranges)“Basic transmitters and receivers”). An appropriate working frequency or channel should therefore be used for long messages.

In particular, the announcement and identification “medical transports“, as defined by the Geneva Conventions and Additional Protocols, 12 August 1949, should be made on the appropriate OSC distress and safety calling frequencies, using the following call format:

The general procedures for urgency and safety communications, including medical transports and obtaining medical advice, are discussed in more detail in article “Terrestrial Urgency and Safety Communications on the VesselsTerrestrial Urgency and Safety Communications“.

Transmission of Urgency and Safety Messages

The two stages to the transmission of Urgency and Safety Messages using DSC procedures comprise:

1 Announcement of the urgency or safety message using a DSC distress and safety calling channel, usually on MF (2187,5 kHz) or VHF (channel 70) in the following format:

2 Transmission of the urgency or safety message on an appropriate channel, as specified in the DSC call, according to the following protocols:

R/T

NBDP

Use FEC mode (ARQ may be used if the message is addressed to a specific station):

Reception of Urgency and Safety Messages

Following receipt of a DSC urgency or safety call announcing a message addressed to “All Ships“, the frequency or channel indicted for the message should be monitored. The DSC urgency/safety “All ships” announcement itself should NOT, however, be acknowledged.

Author

Olga Nesvetailova

Freelancer

Literature

1. General operator’s Certificate for The Global Maritime Distress and Safety System, Course + Compendium, Model Course IMO 1.25, Printed by PMS UK Ltd London, 2004.
2. European Radiocommunications Committee ERC Decision of 10 March 1999 on the harmonised examination syllabi for General Operator’s Certificate (GOC) and Restricted Operator’s Certificate (ROC)(ERC 99 01).
3. IMO GMDSS-Handbook, London, U. K., 2004.
4. Norcontrol Capella GMDSS Simulator, Technical documentations, Kongsberg Maritime Ship Systems, Norway, 2005.
5. INMARSAT MARITIME COMMUNICATIONS HANDBOOK – INMARSAT – London, U. K, 2005.
6. Seafarers’ Training, Certification and Watchkeeping CODE 1995 (STCW Code 95, published by IMO, London, 1996), – Part A Mandatory standards regarding provisions of the annex to the Convention Chapter IV Standards regarding radio personnel.
7. Seafarers’ Training, Certification and Watchkeeping CODE 1995 (STCW Code 95, published by IMO, London, 1996), – Part B Mandatory guidance regarding provisions of the STCW and its annex; Chapter IV Guidance regarding radiocommunication and radio personnel.
8. V. Pipirigeanu, M. Udrea, Introducere in GMDSS – Sistemul Mondial de Primejdie si Siguranta Maritima, Ed. Europolis, Constanta, 2002.
9. Graham D. Lees, William G. Williamson, Handbook for Marine Radio Comunication, e d. LLOYD S OF LONDON PRESSLTD., 2004.
10. ITU Manual for Use by The Maritime Mobile and Maritime Mobile Satellite Services, 2006.
11. IAMSAR Manual – International Aeronautical and Maritime Search and Rescue Manual, 2001.
12. C/S G.003 – Introduction to Cospas-Sarsat System, (G3OCT28.99D Issue 5 – Rev 1 October 1999), C/S Documents published by Cospas-Sarsat in Handbook of Regulations on 406 MHz and 121,5 MHz Beacons, (1999);
13. Tor R. Kristensen – An Introduction to GMDSS, revised GOC Edition, – 7^th edition, Leknes, Norway, 2007.
14. C/S T.001 – Specification for Cospas-Sarsat 406 MHz Distress Beacon, (T1OCT30.99D – Issue 3-Rev. 2 October 1999), Documents published by Cospas-Sarsat in Handbook of Regulations on 406 MHz and 121,5 MHz Beacons (1999).
15. IMO SOLAS (SAVE OF LIVE AT SEA), Consolidated Edition, London, 2001.