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