INTERNATIONAL TELECOMMUNICATION UNION

 

RADIOCOMMUNICATION
STUDY GROUPS

Revision 1 to
Document 8B/TEMP/193-E

31 March 2006

English only

Source:        Document 8B/300 Annex 5, 8B/41, 8B/358, 8B/407, 8B/422

Subject:       Simplification of DSC

Working Party 8B

Draft modification of recommendation itu-r m.493-11
new annexes 3 and 4

 

Summary of Modifications

In response to the IMO liaison statement to ITU-R WP 8B to address DSC complexity issues, a generalized user interface for operation of shipborne equipment has been proposed and suggested as Annex 3 to Recommendation ITU-R M.493-11. Automated procedures in shipborne equipment have been proposed and suggested as Annex 4 to Recommendation ITU-R M.493-11.

This modification has been developed with input from IEC TC 80 (International Electrotechnical Commission Technical Commission Maritime Navigation and Radiocommunication Equipment and Systems) and ETSI ERM TG 26 (European Telecommunications Standards Institute Electromagnetic Compatibility and Radio Spectrum Matters Task Group 26: Maritime).  Several manufactures and administrations participated in the joint IEC/ETSI work.

[Two Liaison statements from IMO have been included in the front of this document for information purposes and will be removed after approval in WP 8B.]


Attachment

Source:        Document 8B/41

Received:    11 March 2004

IMO

Liaison statement to IEC TC 80 AND ITU-R WP 8B

Complexity of DSC operation

 

1           The Sub-Committee on Radiocommunications and Search and Rescue (COMSAR) at its eighth session (16–20 February 2004), expressed its concern about the unnecessary complexity of Digital Selective Calling (DSC) equipment. Feedback from users indicates strongly a negative attitude to the use of DSC - almost invariably voice calls are made rather than use of DSC. Reasons given for this reluctance to use DSC include:

           menu trees too complicated and difficult to use;

           significant variations between different manufacture's equipment; and

           no perceived benefit over voice calling except for distress alerting.

2           With the recent improvements to ITU-R Recommendations regarding DSC and the ongoing work by IEC TC 80 to revise DSC technical standards, an opportunity exists to simplify the operation of new DSC equipment and rectify problems perceived by operators.

3           In the revision of DSC technical standards, IMO requests IEC TC 80 and WP 8B to consider:

           a simplified user interface, using a minimum of menu trees;

           incorporation of ITU-R recommended DSC operational procedures into equipment software wherever possible;

           incorporation, if practicable, of MH/HF automated propagation prediction into equipment software to simplify equipment operation by users unfamiliar with prediction of propagation conditions;

           inclusion of a standard user interface;

           the development of a Class E standard similar to that of Class D; and

           common actuating arrangements for the dedicated distress button (MSC/Circ.862).

 

 


Attachment

Source:        Document 8B/407

Received:    14 March 2006

International Maritime Organization

LIAISON STATEMENT TO ITU-R Working party 8B AND IEC TC80

ADDRESSING THE ISSUE OF DSC COMPLEXITY

 

The IMO would like to thank the ITU-R for the liaison statement Document 8B/TEMP/109(Rev.1) concerning DSC complexity issues.

The Sub-Committee on Radiocommunications and Search and Rescue (COMSAR), at its tenth session (6 to 10 March 2006), whilst considering the issue of DSC complexity, was of the opinion that the addition of the two new annexes 3 and 4 to Recommendation ITU-R M.493-11 went a long way towards meeting the objectives of IMO in simplifying the operation of DSC and supports them, in principle.

 


Draft Modification OF RECOMMENDATION ITU-R M.493-11*

Digital selective-calling system for use
in the maritime mobile service

(1974-1978-1982-1986-1990-1992-1994-1995-1997-1997-2000-2004)

[Note: This Modification includes changes to page 1,2, 26 & 39 of ITU-R M.493-11 and new Annexes 3 & 4.]

The ITU Radiocommunication Assembly,

considering

a)          that selective-calling in the shore-to-ship, ship-to-ship and ship-to-shore directions would expedite the handling of traffic in the maritime mobile service;

b)          that the International Maritime Organization (IMO) has listed a number of operational requirements that should be taken into account when designing a general purpose selective-calling system;

c)          that Chapter IV of the International Convention for the Safety of Life at Sea (SOLAS), 1974, as amended, requires the use of digital selective calling (DSC) for distress alerting and safety calling in the Global Maritime Distress and Safety System (GMDSS);

d)          that neither the selective-calling system described in Recommendation ITU‑R M.257, nor that forming part of the systems described in Recommendations ITU-R M.476 and ITU‑R M.625, can fully meet the IMO performance standards for shipborne equipment;

e)          that the DSC system should be applicable to the maritime mobile service, both for international and national needs;

f)           that it is desirable that the DSC system fulfils the requirements of all types of vessels desiring to use it;

g)          that the Radio Regulations (RR) adopted by the World Radiocommunication Conference (Geneva, 1997) (WRC‑97) provided for the use of maritime mobile service identities by all administrations;

h)          that after experience gained, a need exists to reduce unnecessary alarms and simplify operation of shipborne equipment;

j)           that in certain applications there may be a need to disable DSC automatic channel switching when there is a requirement for vessels to maintain continuous radio watch on a specific radio telephony channel (e.g. port traffic control, bridge-to-bridge communications),

 


recommends

1           that where there is a need for a general purpose DSC system, the system should be designed in accordance with the characteristics given in Annex 1;

2           that where there is a need for simplified versions of DSC equipment, they should be designed in accordance with Annex 2;

3           that in a GMDSS coast radio station installation, sufficient separation should be provided between the DSC distress channel receiver antennas and any transmitting antennas within the installation. This is to avoid any de‑sensitization of the DSC distress channel receivers if any transmitter is used at full power on any designated transmit frequency other than the DSC distress frequencies;

4           that DSC equipment should also be designed in accordance with the requirements specified within Recommendation ITU‑R M.541;

5           that Shipborne equipment should also be designed in accordance with Annexes 3 and 4.

 

TABLE 4.2

Distress acknowledgements

 

 

Type

Applicable to

Technical format of call sequence

 

 

 

 

Ship
station
Class A/B

Ship
station
Class D

Ship
station
Class E

Coast station

Format specifier
(2 iden­tical)

Category
(1)

Self-ID
(5)
1

Tele­command
(1)

Message

EOS
(1)

ECC
(1)

EOS
(2 identical)

 

Rec. ITU-R M.821 expansion sequence
(9)

 

 

0

1

2

3

4

 

 

 

Distress MMSI
(5)

Nature of distress
(1)

Distress coordi­nates
(5)

Time
(2)

Subse­quent commu­nications
(1)

 

 

Frequency
band

Tx

Rx

Tx

Rx

Tx

Rx

Tx

Rx

 

 

VHF

Distress acknowl­edgement (RT)

l

l

 

l

 

 

l

l

116

112

MMSI

110

MMSI

100 to 111

Pos1

UTC

100

127

ECC

127

 

expan1

 

 

Distress acknowl­edgement (EPIRB)

l

l

 

l

 

 

l

l

116

112

MMSI

110

MMSI

112

Pos1

UTC

126

127

ECC

127

 

expan1

 

MF

Distress acknowl­edgement (RT)

l

l

 

 

 

l

l

l

116

112

MMSI

110

MMSI

100 to 111

Pos1

UTC

109

127

ECC

127

 

expan1

 

 

Distress acknowl­edgement (FEC)

l

l

 

 

 

l

l

l

116

112

MMSI

110

MMSI

100 to 111

Pos1

UTC

113

127

ECC

127

 

expan1

 

HF

Distress acknowl­edgement (RT)

 

l

 

 

 

l

l

l

116

112

MMSI

110

MMSI

100 to 111

Pos1

UTC

109

127

ECC

127

 

expan1

 

 

Distress acknowl­edgement (FEC)

 

l

 

 

 

l

l

l

116

112

MMSI

110

MMSI

100 to 111

Pos1

UTC

113

127

ECC

127

 

expan1

 

 1 Distress acknowledgments where the transmitting MMSI and ship in distress MMSI are the same, the message should be interpreted as an self Cancel operation. This should be displayed on all receiving stations. The function should be implemented on new equipment.

 

 

 

 

The message should match the received distress alert information, except for manually generated distress acknowledgements by coast stations.

 

 

 

 

 

Rec. ITU-R M.821 expansion sequence

 

Type

Expansion data specifier
(1)

Enhanced position resolution
(4)

EOS
(1)

ECC
(1)

EOS
(2 identical)

 

expan1

100

Pos5

127

ECC

127

 


TABLE 5

Frequency or channel information


Frequency

0
1
2

X
X
X

X
X
X

X
X
X

X
X
X

X
X
X

The frequency in multiples of 100 Hz as indicated by the figures for the digits HM, TM, M, H, T, U. This should be used for MF, HF equipment.

 

3

X

X

X

X

X

The HF/MF working channel number indicated by the values of the digits TM, M, H, T and U. This should be used for backward compatibility in receive only mode.

Channels

8

X

X

X

X

X

Only used for Recommendation ITU-R M.586 equipment.

 

9

0

X(1)

X

X

X

The VHF working channel number indicated by the values of the digits M, H, T and U.

 

HM

TM

M

H

T

U

 

 

Character
3

Character
2

Character
1(2)

 

(1)   If the M digit is 1 this indicates that the ship stations transmitting frequency is being used as a simplex channel frequency for both ship and coast stations. If the M digit is 2 this indicates that the coast stations transmitting frequency is being used as a simplex channel frequency for both ship and coast stations. If the M digit is 0, this indicates the frequency being used is in accordance with RR Appendix 18 for both single and two frequency channels.

(2)   Character 1 is the last character transmitted.


Annex 3

User interface for operation of shipborne equipment

1           General

The user interface for operation of the DSC equipment should be so designed that it will be easy for the operator onboard the ship to operate the equipment and to compose and initiate the types of DSC messages provided for by the equipment.

2           Definitions:

2.1                 automated procedure: the term given to describe the set of actions necessary to complete the objective of an initiating DSC message or non DSC communication event. .  Four DSC automated procedures are designed to process these. They are the receiving of distress DSC messages, the receiving of non distress DSC messages, the sending of distress DSC alert attempts and the sending of non distress DSC messages.  In addition a fifth procedure is designed to handle non DSC communication events.

             These automated procedures are called:

             -  Received distress automated procedure

             -  Sending distress automated procedure

             -  Received non-distress automated procedure

             -  Sending non-distress automated procedure

             -  Communications automated procedure.

2.2                 default: a value selected or an action taken by the equipment software in the absence of any operator input.

2.3                 DROBOSE:  Distress Relay On Behalf Of Someone Else

2.4                 engaged: the term used to indicate that the equipment is busy handling an automated procedure.

2.5                 factory default: A default value that is set by the manufacturer such that the field or behavior is defined prior to any operator intervention.

2.6                 standby: the term used to indicate that the equipment is not handling an automated procedure, either active or on hold, but is able to receive DSC messages.

2.7                 top level: top level means that items, buttons, or functions are present and visible without requiring any action by the operator (such as scrolling, opening up menus, or removing any obscuring covers, etc.).


3           Controls

3.1.       Dedicated Distress Button to initiate the sending of the distress alert attempt.  This button should have at least two independent actions.  Lifting of the protective lid is considered the first action.  Pressing the distress button is considered as the second independent action.  This button should be red in colour and marked “DISTRESS”. Where a non-transparent protective lid or cover is used, it should also be marked “DISTRESS”. The cover should be protected against inadvertent operation with a spring loaded lid or cover permanently attached to the equipment by e.g. hinges. It should not be necessary for the user to remove seals or to break the lid or cover in order to operate the distress button. This button should be used only for this purpose and it should be able to perform this function at all times. Use of the button without any previous operator actions to compose the alert should initiate the default distress alert attempt. The “default distress alert attempt” consists of ‘undesignated” for the nature of distress, radio telephony for the communication mode, and on HF the transmission of the attempt uses the multi frequency method including all six bands.

The distress button should have priority over all DSC procedures.

3.2        The following controls, buttons or functions should be provided and visible at the top level while the equipment is in standby:

3.2.1.    Distress Function for composing distress alert attempts other than the default distress alert attempt where the operator is able to

           select the nature of distress (the factory default should be undesignated distress),

           on HF select the communication mode (the factory default should be telephone),

           on HF select the method and frequencies of transmission (the factory default should be the multi frequency method on all six bands),

           check the content of the position and time of position information and to manually enter this information if not correct,

prior to initiating the sending of the distress alert attempt with the Dedicated Distress Button.

3.2.2     Call Function for composing non distress DSC messages.

3.2.3     Distress Relay On Behalf of Someone Else Function for composing and relaying the occurrence of a distress event obtained by non DSC means.

3.3 The following controls, buttons or functions should be provided and be visible as noted:

3.3.1     Cancel/Esc/Exit/or equivalent for returning to a previous menu level from any state of the equipment

3.3.2     Enter/Accept/Next/Touch/Press or equivalent for

3.3.2.1  accepting a menu item or

3.3.2.2  going to the next step.

4           Display of messages in plain language

The headings and content of messages should be shown in plain language , for example:

           ‘Radio telephone’ instead of J3E,

           ‘busy’ instead of ‘telecommand 2: 102’.

5           Transmission of DSC messages

5.1        DSC Message composition features

The facilities for choosing and composing DSC messages should be so arranged that it is possible for the operator quickly and precisely to:

5.1.1     compose the content of the DSC message,

5.1.2     review and correct, if needed, the content before transmitting the DSC message.

5.2        Operational guidance to the operator

5.2.1     The operator should only be able to compose the types of DSC messages which are specified in the Tables 4.1 – 4.10.2 of Annex 1.

5.2.2     The equipment should automatically propose the next step for composing the DSC message, for example, when pressing the Enter/Accept/Next/Touch/Press  button or equivalent, if not visible from the context or on the display.

5.3        Defaults

Where options for the items in the DSC message exist (see Annex 1, Tables 4.1 – 4.10.2), the factory default values should be as follows:

after the operator selects the option to compose a non distress DSC message

           if the operator has the option to select a format (destination address) the default format should be ‘individual (120)’,

           if the format (destination address) is either individual (120), a group of ships (114), or a semi-automatic phone call (123), the default MMSI should be some internal indicator that the MMSI is invalid and needs to be entered before transmission can occur,

           if the format (destination address) is an area (102), the default area should be a circle of radius 500 nautical miles centered on the ship,

           if the operator has the option to select a category (priority) the default category should be ‘routine’ unless the routine priority is not allowed (such as in an area or all-ships DSC message) in which case it should be ‘safety’,

           if the operator has the option to select the type of subsequent communication the default value should be radio telephony,

           if the operator has the option to select a frequency or channel for the subsequent communication the default value should be a non distress frequency or channel consistent with the means of subsequent communication and on MF/HF in the same band as the DSC message transmission,

           on MF/HF if the operator has the option to select a the frequency of the DSC transmission, default value should be 2,177 KHz,

           on MF if the operator has the option to select a the frequency of the DSC transmission,default value should be 2,177 KHz,

           on HF if the operator has the option to select a the frequency of the DSC transmission, default value should be in the 8 MHz band,

           all other parameters, for example the position, self ID, time of position, and end of sequence character, should be automatically entered by the equipment,

           the category should not be ‘remembered’ when the call composition option is selected at a later time but should be reset to the factory default; this requirement does not mean the equipment is unable to provide the operator with the option to send pre-composed, customized DSC messages with a single action,

           for example, if there is only a single ‘call’ button, menu selection, or equivalent for initiating a non distress DSC message, the default DSC message should have format ‘individual’ and category ‘routine’,

after the operator selects the option to compose a Distress Relay On Behalf Of Someone Else (DROBOSE)

           if the operator has the option to select a format (destination address) the default format should be ‘individual (120)’,

           if the format (destination address) is individual (120), the default MMSI should be the all coast stations MMSI 009990000 [if such an MMSI has international acceptance]. Otherwise it should be some internal indicator that the MMSI is invalid and needs to be entered before transmission can occur,

           if the format (destination address) is an area (102), the default area should be a circle of radius 500 nautical miles centered on the ship,

           the default nature of distress should be ‘undesignated (107)’,

           the default MMSI for the vessel in distress should be ‘unknown (five 126’s)’,

           the default position and time of position should be unknown,

           the default means of subsequent communication should be radio telephony,

           on MF/HF the default band of the DSC transmission should be on the 2 MHz band,

           on MF the default band of the DSC transmission should be on the 2 MHz band,

           on HF the default band of the DSC transmission should be on the 8 MHz band,

           all other parameters, for example the, self ID, the distress relay telecommand 1 parameter, the category (distress), and end of sequence character should be automatically entered by the equipment,

           the format, MMSI of the vessel in distress, the nature of distress, the position and time of position should not be ‘remembered’ when the DROBOSE composition option is selected at a later time but should be reset to the defaults.


5.4        Other items

5.4.1     If the called station is a ship station or a group of ship stations the equipment should request input of a channel number (frequency in case of MF). The equipment should assist the operator by suggesting a suitable inter-ship channel, on VHF for example channel 6.

5.4.2 Automated HF subsequent communication channel selection for non distress DSC messages. There is a simplex set and duplex set (contains the distress channels) for HF for both voice (3000 Hz) and data (500 Hz) communication modes. Selection of the appropriate channel from these sets should follow the following

           The band of the communication channel should be the band of the DSC message

           The telecommand 1 parameter determines the choice of voice or data channels

           DSC messages directed to a coast station (i.e. MMSI commencing 00) should let the coast station decide

           All other DSC messages should select a channel from the simplex frequencies

5.4.3  Use of the distress channels should be avoided and for routine communications use of the distress channels should not be allowed.


Annex 4

Automated procedures in shipborne equipment

1           General

Automated procedures are the incorporation of ITU-R recommended DSC operational procedures into equipment software.

The equipment should initiate (start) one of five automated procedures whenever the equipment becomes engaged in a new communication event. Four of these automated procedures handle events initiated by sent and received DSC messages and the fifth automated procedure handles radio telephony established by non DSC means. One of these five automated procedures is  initiated by

a)          sending a distress alert,

b)          receiving a DSC message containing distress information,

c)          sending an individually addressed relay containing distress information,

d)          sending distress relay on behalf of someone else,

e)          sending a DSC message containing no distress information,

f)           receiving a DSC message containing no distress information,

g)          engaging in traffic initiated by non DSC means.

Once initiated by any of the events listed in a-g, the automated procedure should handle all the tasks required to satisfy the objectives of the initiating event. These tasks should include the handling any subsequent DSC messages that may be pertinent (relevant) to the objectives of the automated procedure and appropriately updating the automated procedure, providing the operator with any possible options, and keeping the operator informed of the progress until either the operator terminates the automated procedure or conditions warrant that the automated procedure self terminates. Automated procedures should be able to be run in parallel. Whereas all DSC automated procedures continuously monitor the watch receiver only one active automated procedure has control of the transmitter and general receiver.  The reception of any DSC message not pertinent to an automated procedure should not disrupt that procedure but should be appropriately allocated to the appropriate ongoing automated procedure or initiate a new automated procedure.

2           Definitions:

2.1        acknowledged: when used to describe an automated procedure it indicates that the objective of the initial DSC message has been achieved.

2.2        active: the term used to describe an automated procedure which has control of the general receiver and transmitter and is thus able to engage in subsequent communications and receive DSC messages on both the watch receiver and general receiver.

2.3        automated procedure: the term given to describe the set of actions necessary to complete the objective of an initiating DSC message or non DSC communication event.  Four DSC automated procedures are designed to process these. They are the receiving of distress DSC messages, the receiving of non distress DSC messages, the sending of distress DSC alert attempts and the sending of non distress DSC messages.  In addition a fifth procedure is designed to handle non DSC communication events.

These automated procedures are called:

-  Received distress automated procedure

-  Sending distress automated procedure

-  Received non-distress automated procedure

-  Sending non-distress automated procedure

-  Communications automated procedure.

2.4        critical errors: a set of information characters obtained from one or more received DSC messages is considered to have critical errors if the automated procedure needs information characters from that set in order to proceed or perform any task, but the required information characters are in error (for example, an acknowledgement cannot be composed to an individual DSC message that has errors in the sender’s MMSI).

2.5        default: a value selected or an action taken by the equipment software in the absence of any operator input.

2.6        distress DSC message: A DSC message or acknowledgement containing the distress information.

2.7        distress event: a unique distress situation identified by two (VHF) or three (MF/HF) parameters of the distress information; the MMSI of the vessel in distress and the nature of distress and on MF/HF the mode of subsequent communication.

2.8                 distress information: the symbols within a DSC message describing a distress situation consisting of the MMSI of the vessel in distress, the nature of distress, the position of the vessel in distress, the UTC time of that position, and the mode of subsequent communication.

2.9                 DROBOSE:  Distress Relay On Behalf Of Someone Else

2.10      DX/RX: a notation used to describe the time diversity structure of DSC messages (see Figure 1 of Annex 1). One has to be careful not to confuse the ‘RX’ notation when used to indicate the symbol position in the DSC message structure (as in §4.1 of Annex 1) with its use to indicate reception (as in §8.3.2 of Annex 1).

2.11    engaged: the term used to indicate that the equipment is busy handling an automated procedure.

2.12    factory default: A default value that is set by the manufacturer such that the field or behavior is defined prior to any operator intervention.

2.13      general receiver: this unit is the receiver part of the transceiver used for the reception of all subsequent communications and on HF the reception of non distress DSC acknowledgements. It is important to distinguish this unit from the watch receiver (see below).

2.14      identical: a set of information characters is considered identical to another set of information characters if all pairs of corresponding information characters are equal or, if a pair of corresponding information characters is not equal, one of the pair is in error.

2.15      information characters: the set of symbols in the DSC message that contain the items of interest for the recipient and is used to compute the ECC symbol that terminates the message. These symbols are repeated in the DX/RX time diversity pattern.

2.16      initial DSC message: the DSC message that starts an automated procedure.

2.17      non distress DSC message: DSC messages and acknowledgments that do not contain the distress information.

2.18      objective: when in reference to a DSC message or automated procedure it is the goal or intent of the item; usually this goal or intent is to establish subsequent communications or request information.

2.19      on hold: the term used to describe an automated procedure which does not have access to the transmitter and general receiver and therefore cannot engage in subsequent communications and is only able to receive DSC messages on the watch receiver.

2.20      operator options: are any choices the operator can make while the automated procedure is engaged.

2.21      parallel event handling: the background process of handling a received DSC message that is not pertinent to the active automated procedure.

2.22      pertinent to the automated procedure: an expression used primarily with reference to DSC messages to indicate that the message has something to do with the procedure and is therefore ‘handled’ by the procedure. A DSC message is pertinent to an automated procedure if the set of information characters in the DSC message has the correct values.

2.23      standby: the term used to indicate that the equipment is not handling an automated procedure, either active or on hold, but is able to receive DSC messages.

2.24      two-tone alarm: an alarm consisting of a repetition of the 2200 Hz frequency for 250 ms followed by a 1300 Hz frequency for 250 ms. This alarm is used for the initiation of the received distress DSC automated procedure. The characteristics of this alarm should not be able to be altered.

2.25      urgency alarm: an alarm consisting of a repetition of the 2200 Hz frequency for 250 ms followed by 250 ms period of silence. This alarm is used for the initiation of the received non distress DSC automated procedure when the category of the initiating DSC message is ‘urgency’. The characteristics of this alarm should not be able to be altered.

2.26      watch receiver: this unit is the separate receiver in DSC radios that continuously monitors the DSC distress frequencies on MF/HF, 2 187.5 kHz on MF, and channel 70 on VHF. On MF/HF it is sometimes referred to as the scanning receiver.

3           Tasks of Automated Procedures

3.1        Tasks common to all automated procedures handling DSC messages

3.1.1     Handling alarms:

3.1.1.1  The sounding of any alarm should simultaneously display the reason for the alarm and the means to silence it.

3.1.1.2  Alarms should sound appropriate to the automated procedure when a received DSC message either initiates or acknowledges the automated procedure with the two-tone alarm being reserved for the initiation of the received distress procedure, and the urgency alarm being reserved for the initiation of the received non distress procedure when the category of the initiating DSC message is ‘urgency’.

3.1.1.3  Only the first occurrence of a received DSC message should sound the alarms described in 3.1.1.2.

3.1.1.4  All received DSC messages that do not sound an alarm as specified in 3.1.1.2 should sound a brief, self-terminating alarm to inform the operator of the reception.

3.1.2     Displaying Stages of the Automated Procedure

The automated procedure should display the stages and/or activity in order to indicate the progress of the procedure.

3.1.3     Tuning the radio:

3.1.3.1  Tuning of the general receiver and transmitter for reception or transmission of required acknowledgments, repeat transmissions, relays, or subsequent communications should be handled automatically.

3.1.3.2  Any automated tuning action that could potentially disrupt ongoing subsequent communications should provide the operator with at least a ten second warning. The operator should then be provided with the opportunity to pause the action. In the absence of operator intervention the automated action should proceed.

3.1.4     Displaying Operator Options

Options should only be provided at those times the option is appropriate.

3.1.5     Handling DSC messages not pertinent to the active procedure

The received DSC message is either allocated to the correct automated procedure running in the background on hold or initiates a new automated procedure on hold.

3.1.6     Displaying Warnings

Warnings should be displayed when the operator attempts to do anything that does not follow the guidelines given by ITU and IMO. The operator should have the option to go back to the stage of the automated procedure where the action was taken that caused the warning.

3.1.7     Handling DSC messages containing errors

3.1.7.1  A DSC message with errors is pertinent to an automated procedure if the set of information characters in the DSC message is identical as defined in the “definitions” section to the set of information characters normally used to determine pertinence.

3.1.7.2  Automated procedures initiated by DSC messages with critical errors should sound the same alarm they would sound if the DSC message were received error free but the alarm should self-terminate.

3.1.7.3  Automated procedures are encouraged to utilize subsequent DSC messages pertinent to the automated procedure to reduce the number of receive errors in the set of information characters that are important to the automated procedure. In no case should the reception of subsequent DSC messages increase the number of errors in the set of information characters important to the automated procedure.

3.1.7.4  No automated procedure should allow the transmission of further DSC messages with errors.

3.1.7.5  If critical errors prevent an automated procedure from setting up an operator option or performing any automated action, that option should be disabled or that action not performed.

3.1.7.6  Automated procedures should not be considered acknowledged until all the critical errors in the set of acknowledgement information characters have been received correctly or corrected by repeat reception.

3.1.7.7  Information that is normally displayed that contains errors should be displayed to the full extent possible; for example, digits in the MMSI or position information that are received correctly should be displayed in their correct positions and those that are not should be indicated by some special error symbol.

3.1.8     Transmission of DSC messages

Transmission of DSC messages is should encouraged to use a prioritized wait scheme. If the channel is not free, and the DSC message is a distress alert, the alert should be transmitted as soon as the channel becomes free or after 10 seconds on MF or HF or 1 second on VHF, which ever occurs first. For all other DSC messages, the automated procedure should wait for the channel to become free and then delay transmission of the DSC message for a specified wait time. Distress DSC messages (except for alerts), urgency, safety, routine and test DSC messages should wait one, two, three, and four “fixed” units of time plus a random addition described below, respectively, before attempting to transmit. Transmission occurs if and only if the channel is still free after this wait time has elapsed, otherwise the process is repeated. The fixed “unit” of time should be 100 ms on MF and HF and 50 ms on VHF. The randomly generated component should be some positive integer with resolution in milliseconds between zero and the fixed interval.  On MF/HF the channel is considered free if the receiver hardware or DSP software is unable to recognize the DSC tones. 

3.1.9     Automated termination

3.1.9.1 Automated procedures should have an automated termination timer which whose factory default values can be setchanged by the operator. It should be possible to disable this timer. Unacknowledged sending distress automated procedures should not have a termination timer, however after acknowledgement a termination timer is optional.

3.1.9.2 At least 10 seconds prior to automatic termination, a warning with a discrete aural alarm should be displayed giving the operator the opportunity to stop the termination.

3.2        Tasks specific to certain automated procedures

3.2.1     Tasks of Automated Procedures initiated by receiving non distress DSC messages:

3.2.1.1      Display of Elapsed time.

The elapsed time since receiving the initiating DSC message should be displayed or after any requested acknowledgment has been sent, the elapsed time since sending the acknowledgement should be displayed. Sending repeat acknowledgments should not affect the time display.

3.2.1.2      Handling acknowledgments.

3.2.1.2.1      If the equipment has been set up to automatically acknowledge individually addressed polling, position request, or test DSC messages, no alarm should sound and the automated procedure should self-terminate.

3.2.1.2.2      All individually addressed DSC messages with subsequent communications should be automatically acknowledged as a default. In this case the alarm should sound after the acknowledgement is sent.

3.2.1.2.3      Acknowledgement options should only be made available to the operator when the received DSC message requests an acknowledgement.

3.2.1.2.4      When acknowledgments are requested the automated procedure should provide the operator with up to three possible acknowledgement options based upon the received DSC message as follows:

3.2.1.2.4.1   Able to comply: This option should be provided if the frequencies and mode of subsequent communication are provided by the received DSC message and the equipment is capable of handling the requested communications, or if the received DSC message is a polling, position request, or test that has not been automatically acknowledged,

3.2.1.2.4.2   Able to comply with a mode or frequency change: This option should be provided if the received DSC message requests subsequent communications.

3.2.1.2.4.3   Unable to comply: This option should be provided if the received DSC message contains subsequent communications or is a position request. The sending of this acknowledgement indicates a refusal and should terminate the automated procedure.

3.2.1.2.5      The automated procedure should automatically compose the acknowledgement messages based upon the received DSC message as shown in Figure 2 and Figure 3 of Annex 1.

3.2.1.2.5.1   ‘Able to comply’ acknowledgments should be composed in entirety by the automated procedure.

3.2.1.2.5.2   ‘Able to comply with a mode or frequency change’ acknowledgements should only require the entry/selection of a new mode and/or frequency.

3.2.1.2.5.3   ‘Unable to comply’ acknowledgments to DSC messages containing subsequent communications should only require the entry/selection of one of the ten telecommand 2 ‘reason’ symbols specified in Table 3 of Annex 1.

3.2.1.2.5.4   ‘Unable to comply’ acknowledgments to position requests if implemented should only require a single action by the operator to send. The procedure should automatically place the ‘no information symbol’ in the position and time messages of the acknowledgement.

3.2.1.2.6      The operator should be able to resend a duplicate of the first acknowledgement in automated procedures that have subsequent communications.

 

3.2.2     Tasks of Automated Procedures initiated by sending a non distress DSC message:

 

3.2.2.1      Display of elapsed time

             The elapsed time since sending the initial DSC message should be displayed or after the automated procedure has received a requested acknowledgment, the elapsed time since acknowledgement should be displayed. Receiving repeat acknowledgments should not affect the time display.

3.2.2.2      Resending the Initial DSC message

3.2.2.2.1      If no acknowledgement is requested the option to resend the initial DSC message should remain available until the procedure is terminated.

3.2.2.2.2      If an acknowledgement is requested the option to resend the initial DSC message should remain available until the acknowledgment has been received.

3.2.2.3      Handling the reception of a delayed acknowledgement

             If an acknowledgement appropriate to this automated procedure is received but the operator has terminated the automated procedure prematurely, the appropriate automated procedure should be reconstructed based on the acknowledgement and the operator informed of the situation.

3.2.3     Tasks of Automated Procedures initiated by receiving a distress DSC message or sending a distress relay on behalf of someone else:

3.2.3.1      Display of elapsed time

             The elapsed time since receiving the initial DSC message should be displayed or after the automated procedure has been acknowledged, the elapsed time since acknowledgement should be displayed. Receiving repeat acknowledgments should not affect the time display.

3.2.3.2      Determining operator options

3.2.3.2.1      On HF the operator should have the option to set the general receiver and transmitter to any one of the six distress frequencies of subsequent communication.

3.2.3.2.2      The option to send a relay should always be available until the automated procedure is terminated.

3.2.3.2.3   Distress alert acknowledgments and relay acknowledgement options

3.2.3.2.3.1   These options should not be made available until a DSC message has been received that can respond to the acknowledgement.

3.2.3.2.3.2   These options should be available immediately after reception of the appropriate DSC messages and not wait until certain conditions for their use, such as time limits, are fulfilled.

3.2.3.2.3.3   Once these options are available, they should remain available until the automated procedure is terminated.

3.2.3.3      DSC Message composition

3.2.3.3.1      The automated procedure should automatically compose relays, distress alert acknowledgments and relay acknowledgments based upon the received DSC messages.

3.2.3.3.1.1   the distress information should be taken from the distress DSC message which has the latest UTC time stamp.

3.2.3.3.1.2   Distress alert acknowledgements and relay acknowledgements should require no data entry by the operator except on HF where the frequency of the DSC message may be selected,

3.2.3.3.2      relays should only allow the entry of the addressing mode (format) and destination address and on HF, the mode of subsequent communication and the frequency of the DSC message,

3.2.3.3.3      on HF the automated procedure should indicate those frequencies on which DSC messages pertinent to the automated procedure have been received as the preferred choices, however the operator should be allowed to choose any of the six distress frequencies.

3.2.3.4      Tuning of the radio after acknowledgment on HF

             The automated tuning should cease upon reception or sending of a distress alert acknowledgement or a distress relay acknowledgment addressed to multiple stations. However, the operator should be provided with sufficient information to manually tune to the working frequencies of the most recently received DSC message.

3.2.3.5      Handling individually addressed relays

3.2.3.5.1      The sending or receiving of individually addressed relays should initiate their own automated procedure separate from the automated procedure that may be handling distress DSC messages concerning the same distress event.

3.2.3.5.2      The option to send a distress alert acknowledgement should never be available during this automated procedure.

3.2.3.6      Handling DSC messages with critical errors

             If the subsequent communication parameter of the distress information is received in error, radio telephone should be assumed and an indication that the parameter was received in error should be made known to the operator.

3.2.3.7      Handling the self-addressed distress alert acknowledgement

             If the MMSI of the sender of a distress alert acknowledgement is the same as the MMSI of the vessel in distress, the automated procedure should recognize the message as an attempt to cancel the distress alert and inform the operator accordingly.

3.2.3.8      Extended DSC sentences

The automated procedure should be able to successfully receive and decode single frequency alert attempts that have extended sentence information at the end of some or all of the individual alerts.

3.2.3.9      MF/HF Only Scanning for distress DSC messages on MF/HF

The received distress automated procedure should scan all six distress DSC channels if not already doing so.

3.2.4     Tasks of Automated Procedures initiated by sending a distress alert attempt:

3.2.4.1      Display of elapsed time

3.2.4.1.1      The time remaining to the sending of the next distress alert attempt should be displayed prior to acknowledgment by DSC.

3.2.4.1.2      The elapsed time since acknowledgement should be displayed after acknowledgment by DSC. Receiving repeat acknowledgments should not affect the time display.

3.2.4.2      Resending of the distress alert attempt

3.2.4.2.1      The unacknowledged distress alert attempt should be automatically resent after a 3.5 to 4.5 minute wait.

3.2.4.2.2      The automatic resending of the distress alert attempt should automatically terminate after acknowledgement by DSC.

3.2.4.2.3      Resent distress alert attempts should contain updated position and time of position information.

3.2.4.3      Determining operator options

3.2.4.3.1      The option to manually resend the distress alert attempt at any time should remain available until the distress alert has been acknowledged by DSC.

3.2.4.3.2      On HF the operator should have the option to change the frequencies of the distress alert attempt and the option to select between the single frequency or multi frequency method.

3.2.4.3.3      The option to pause the countdown to the next distress alert attempt should be available prior to acknowledgement by DSC.

3.2.4.3.4      The option to cancel the distress alert should be available prior to acknowledgement by DSC.

3.2.4.3.5      The option to terminate the procedure should only be available after acknowledgment by DSC.

3.2.4.4      The distress alert cancel procedure

The cancel procedure consists of the cancel operation on all bands utilized by the distress alert attempts (on VHF and MF there is only one cancel operation whereas on MF/HF there may be up to six). The cancel operation consists of a DSC cancel message (a self-addressed distress alert acknowledgement) followed by a voice cancel on the corresponding frequency of subsequent communication. The phrase “voice cancel” refers to the part of the cancel done over the subsequent communication frequencies whether it is by radio telephony or on MF and MF/HF by data.

3.2.4.4.1      Upon selection of the cancel option the sending distress automated procedure should provide an explanation of the cancel procedure to the operator and provide the option to either continue or return and not do the cancel.

3.2.4.4.2      If the operator selects to proceed with the cancel procedure the sending distress automated procedure should pause the countdown to the next automated sending of the distress alert attempt and wait (if necessary) until any alert within an attempt is transmitted to completion before allowing the operator to initiate the first cancel operation.

3.2.4.4.3      The operator options during the cancel procedure should be to terminate the cancel procedure and to start the cancel operation.

3.2.4.4.4      If the cancel procedure is terminated before the first cancel operation is started, the sending distress automated procedure should resume from where it left off. However, once the cancel operation is started, the option to terminate the cancel procedure should not be available until the cancel procedure is completed.

3.2.4.4.5      The status of the cancel procedure should be displayed.

3.2.4.4.6      The operator should be provided with the appropriate text for the voice cancel at the time of the voice cancel.

3.2.4.4.7      The cancel operation should be able to be repeated on any band but a warning should be provided that the cancel has already been done on this band;

3.2.4.4.8      Special considerations for MF/HF

3.2.4.4.8.1   The status of each of the bands should be displayed;

3.2.4.4.8.2   Once one band is cancelled the option to end the cancel procedure should not be available until ALL utilized bands are cancelled;

3.2.4.4.9      When the cancel procedure is completed, the sending distress automated procedure should be considered acknowledged and the fact that a cancel was performed should be displayed.

3.2.4.5      MF/HF only scanning for distress alert acknowledgements on MF/HF

The sending distress automated procedure should scan all six distress DSC channels if not already doing so.

3.2.5     Radio Telephone Communications Automated Procedure

The equipment should also be provided with a communications function for radio telephony that is compatible with the DSC automated procedures described in this Annex. This automated procedure should have:

3.2.5.1  the ability to switch between being active or being on hold at the discretion of the operator,

3.2.5.2  the ability to be terminated at the discretion of the operator,

3.2.5.3  the ability to select the channels for the communications, and

3.2.6Other Non-DSC Automated Procedures

Any other non DSC functionality that is included in the equipment should

3.2.6.1  be able to be activated or placed on hold at the discretion of the operator,

3.2.6.2  never control the watch receiver such that DSC automated procedures, either active or on hold, are unable to receive DSC messages on the watch receiver,

3.2.6.3  be able to be terminated by the operator.

3.3        Tasks concerning multiple automated procedures

3.3.1     Number of simultaneous automated procedures

Facilities should be provided to handle a minimum of sevensix simultaneous automated procedures including with a reserve of one. The initiation of the reserve automated procedure should

a. warn the operator that the equipment cannot handle another automated procedure and that one automated procedure should be terminated,

b. prevent the operator from initiating any new automated procedures except for the sending of a distress alert and,

c. warn the operator that the reception of an additional DSC message that would initiate an automated procedure if the equipment were in standby will result in the automatic and immediate termination of an inactive automated procedure where

d. the automatic and immediate termination should be based upon age and priority.

3.3.2     Sending distress automated procedure

When initiating a sending distress automated procedure, automatic immediate termination of all other automated procedures (if any) is encouraged but not required.

3.3.3     Operator options

3.3.3.1 The operator should be able to freely navigate between the automated procedures except when engaged in an unacknowledged sending distress automated procedure.

3.3.3.2 When the operator makes any one of the automated procedures on hold active, the automated procedure that was active (if any) should automatically go on hold.

3.3.4     Unacknowledged poll, test, or position request automated procedures received on hold

If any of these automated procedures is set to automatically acknowledge, it should automatically acknowledge and self terminate as soon as all remaining automated procedures are on hold.

3.4        Warnings:

Warnings should be provided when the operator attempts to do the following:

3.4.1     send a relay before three minutes have elapsed since the automated procedure started,

3.4.2     send a non individually addressed relay,

3.4.3     send a distress alert acknowledgement (requires coast station permission),

3.4.4     send an all stations (116 format) distress relay acknowledgement (should be sent by coast station only),

3.4.5     send an acknowledgement to a DSC message containing no distress information that is not individually addressed,

3.4.6     cancel a distress alert,

3.4.7     send any DSC message after the objective of the automated procedure has been obtained,

3.4.8     terminate the automated procedure before the objective has been reached,

3.4.9     terminate the automated procedure if engaged in subsequent communications.

 

 

 

 

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*   This Recommendation should be brought to the attention of the International Maritime Organization (IMO).