Digital Selective Calling System

I. Translate the following text

Digital Selective Calling System is an integral part of the GMDSS and is used for transmitting distress alerts from ships and for transmitting the associated acknowledgements from coast stations. The DSC system is very comprehensive and caters for setting up of all types of calls using internationally agreed codes. It is also used by ships and coast stations for relaying distress alerts and for other urgency and safety calls. DSC encoders/decoders, in some circumstances, can be interfaced with existing equipment. A dedicated DSC watch receiver is required to keep continuous watch on the distress frequency; this can be a simple single channel receiver.

DSC is basically a calling system. Each call consists of a packet of digitized information of one oа four priorities: Distress, Urgency, Safety or Routine. Messages can be routed to “All Stations”, to an individual station or to a group of stations, using their Maritime Mobile Selective-call Identity Code (MMSI). Distress messages are automatically broadcast to “All Stations”. In addition to the MMSI of source and destination stations, information can be conveyed in the DSC message. For example, to aid the Rescue Services, the DSC Distress alert message is configured to contain the following:

1. Ship’s identity (the nine digit MMSI);
2. Time;
3. Nature of distress (in the form of a standard code);
4. Ship’s position.

Where fitted, ship’s officers should ensure they are fully conversant with the procedure for entering the necessary information into the DSC equipment. At sea, unless provided automatically form a navigation system, ship’s position should be updated at least once during each watch period.

The content of a DSC call includes the numerical address of the station (or stations) to which the call is transmitted, the self-identification of the transmitting station and a message, which contains several fields of information indicating the purpose of the call.

Various types of DSC calls are available, being broadly either distress and safety related calls or “commercial” calls (to indicate that a commercial communication, e.g. a telephony or telegraphy call etc., is required). In the case of VHF, automatic connection to the public network can also be established through suitably equipped coast stations.

The receipt of DSC call by a receiving stations is accompanied by a suitable display or printout of the address, the self-identification of the transmitting station and the content of the DSC message, together with an audible or visual alarm or both for certain categories of calls (e.g. for distress and safety related calls).

In order to increase the probability of a DSC distress call or a DSC distress relay being received it is repeated several times to form a distress call attempt.

Summarizing all above information, one may say that Digital Selective Calling is a form of data transmission, and calls sent by this technique can be printed out or shown on a visual display unit. The system is selective and calls can be sent to a specific station, groups of stations or to all stations. However, the primary purpose of a digital selective call is to establish communication between stations so that information can be sent either by radiotelephony (RT) or narrow band direct printing (NBDP).

II. Give a summary of the text above.

III. Answer the following questions

1. Integral part of what system is the DSC?

2. What is DSC is used for?

3. What type of system is DSC basically?

4. What does the content of the DSC include?

5. What types of DSC calls are available?

6. What is accompanied the receipt of DSC call by?

7. What is done to increase the probability of a DSC distress call or a DSC distress relay being received?

IV. Translate the following words and word combinations from English into Russian.

Digital selective calling, distress alert, coast station, to cater for, internationally agreed code, encoders/decoders, to keep continuous watch, the distress frequency, Maritime Mobile Selective-call Identity Code, rescue service, to be conversant with, an audible or visual alarm, distress call attempt, narrow band direct printing.

V. Translate the following sentences from Russian into English

1. Целью ГМССБ является обеспечение любого судна не зависимо от района плавания надежной связью в качестве существенного фактора безопасности.

2. Радиооборудование, установленное на судне, должно обеспечивать передачу оповещений о бедствии в направлении судно-берег, по крайней мере, двумя отдельными и независимыми средствами, каждое из которых использует различные виды радиосвязи.

3. Для эффективной работы радиослужб, входящих в состав ГМССБ, акватория Мирового Океана разделена на четыре морских района плавания судов.

4. Во всех районах должна быть обеспечена постоянная возможность оповещения о бедствии.

5. Каждое судно должно быть оборудовано радиоаппаратурой в соответствии с районом плавания, а не по какому-либо другому критерию (водоизмещение, назначение и т.д.)

UNIT 3

Part I

I. Read and translate the following text

EMERGENCY POSITION INDICATING RADIO BEACON (EPIRB)

EPIRBs are to be mounted near the navigating bridge in such a manner that they can float free and activate automatically in case of rapid sinking. There are basically two types of EPIRBs, the 406 EPIRB and the L-band (Inmarsat-E) EPIRB. Both are satellite based EPIRBS. A new VHF DSC EPIRB is planned for use after 1 February 1999, which will be limited to coastal areas.

The 406 EPIRB is satellite based, transmitting on 406.025 MHz and on 121.5 MHz for homing by SAR aircraft. There are two categories of 406 EPIRB. Category 1 EPIRBs must be able to float free and activate automatically as well as manually. Category 1 EPIRBs are required by GMDSS. Category 2 EPIRBs may be carried as a second EPIRB or for storage in a survival craft.

All EPIRBs must be able to float in an upright position, with antenna deployed, and have a flashing strobe light to assist visual locating by rescue craft. The operating light of an EPIRB battery shall be at least 48 hours continuous operation. Battery life is typically five years.

The 406 EPIRB sends its signal to an orbiting COSPAS-SARSAT satellite, which stores the EPIRB message until it can be downloaded to a land, based local user terminal (LUT) that computes the position before relaying to an RCC. Depending on the location along the orbit path, it can take from 60 to 90 minutes for the EPIRB message to reach the appropriate RCC. The 406 EPIRB signals can be received worldwide in any sea area. The 406 EPIRBs use a unique vessel identification code, which identifies the EPIRB and/or the EPIRB’s manufacturer. An RCC receiving an EPIRB alert can contact the EPIRB’s manufacturer or the RCC in the country of origin to obtain vessel’s identification. Each EPIRB therefore, whether new or transferred from another vessel, must be registered. In the USA NOAA as the COSPAS-SARSAT mission control agency maintains a database of all EPIRBS purchased in the USA. The information is available to any RCC of any nation.

The L-band EPIRB (INMARSAT-E) transmits on 1.6 GHz (earth to space) and relayed by INMaRSAT to the nearest RCC. INMARSAT-E is capable of transmitting more information regarding identity and type of distress than a 406 EPIRB. However, L-Band EPIRBS are limited to only the areas of INMARSAT coverage (70ºN to 70ºS).

Testing of EPIRBs is required monthly to ensure their readiness. Check the strobe light, battery due date, the mounting and the float free device. To prevent false alerts, after each test make sure the EPIRB is remounted before the control switch is returned to the “automatic” position.