超星 - 作业（六）

单选题

What is Omni-directional antenna?

An antenna which is capable of line-of sight communication with a satellite without requiring any pointing.
B. Generally it is used on an Inmarsat-M MES.
C. Generally it is used on an Inmarsat-F MES.
D. This is a kind of directional antenna.

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单选题

How is maximum coverage provided by satellites in the GMDSS?

A. There are four satellites in polar orbit.
B. There are four satellites in geostationary orbit.
C. Each service (Inmarsat-F, - B, -C, and-M) has four satellites in orbit.
D. GMDSS optimizes coordinated use of COSPAS SARSAT satellites.

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单选题

Which one of the following Inmarsat services provides communications by telephone, facsimile (fax), and data?

A. Inmarsat-F / B.
B. SafetyNET.
C. Inmarsat-C.
D. VHF FM.

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单选题

How is a distress alert rapidly initiated on board the vessel?

A. By dialing the correct code on the telephone remote unit.
By contacting the CES operator, and announcing a distress condition is in existence.
C. By pressing a " distress button " on the equipment.
D. By contacting the CES operator using the radiotelephone distress procedure " May-day…” etc.

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单选题

Which is provided by Inmarsat Standard-C via traditional facsimile service?

A. Transfer of letters,
B. Transfer of voice.
C. Transfer of image.
D. All of the above.

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单选题

How is global coverage provided by satellites in the maritime satellite service?

A. Four satellites in polar orbit.
B. Four satellites in geostationary orbit 35, 700 km above the equator.
C. Four satellites in geostationary orbit for each Inmarsat Service (Standard-F, Standard-B, Standard-C and Standard-M).
D. Through coordinated use of COSPAS SARSAT satellites.

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单选题

What does " DHSD " mean in GMDSS?

A. Duplex High Speed Data.
B. Department of Homeland Security in Dominica.
C. Digital High School.
Data Handling System Department.

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单选题

The Inmarsat-C system allows___________.

A. two types of closed networks
B. data reporting networks, identified by a Data Reporting Network Identification (DNID) Code
C. EGC FleetNET networks, identified by an EGC Network Identification (ENID) Code
D. all of the above

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单选题

What is meant by the characters " GA + " on an Inmarsat terminal?

A. General address (to all stations)
B. Go ahead.
C. The instruction to " give address”.
D. None of the above.

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单选题

What will most likely happen if a satellite’s elevation becomes very low?

A. Changes in the elevation have no effect on communications.
B. Communications range through the satellite will likely be maximized.
Communications through the satellite will likely become difficult or impossible to establish.
D. This indicates that the vessel should effect a course change to minimize shadowing.

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