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Inmarsat system

Northwest Spirit uses satellites in the Inmarsat system. Inmarsat, or International Maritime Satellite, is an international partnership of government and private entities representing 75 countries. Headquartered in London, its charter is to provide mobile satellite communication services to the world. Inmarsat was established in 1979 and began providing services in 1982. Currently, Inmarsat uses four of its own satellites and leases maritime communication capacity on several other satellites. All of the units in the Inmarsat system are in geosynchronous orbits.

Channel/Frequency Assignments1

The frequencies used in marine radiotelephone communication are established for use by specific services in specific locations. These frequencies should only be used for the type of communication for which they were intended.

Emissions

In VHF transmissions, the type of emission used is frequency modulation (FM).

International Distress, Calling and Answering Frequencies

These frequencies are set aside for the primary use of distress, urgency and safety communications. They may also be used to initiate a call to other stations or to receive their replies, in which case a mutually satisfactory working channel can be determined. Channel 16 (156.800 MHz) on VHF has been designated for this purpose.

Note: A working channel is a channel other than a pre-designated channel

that is used for the passage of information or messages from one station to another. You should never send messages or information an the calling channel. This channel is used for contact only. When it is known that a station you want to communicate with is operating on a working frequency, it is not necessary to employ the calling frequency. It is permissible to wait until the communication terminates and then call the station with which you wish to communicate on the working frequency.

Watchkeeping

When at sea or in port, ships fitted with radiotelephone equipment should

keep watch on the frequency 156.800 Mhz. (Channel 16 VHF).

When at sea, ships required by law to be fitted with VHF radiotelephone

equipment (compulsorily fitted) must keep a continuous watch on the frequency 156.800 Mhz. (Channel 16 VHF) or other frequencies specifically designated on their licences, except when actually engaged in conducting communications on their working frequencies.

For compulsorily fitted vessels, the very high frequency (VHF) regulations

state that watchkeeping on the VHF band must begin at least 15 minutes

before the vessel leaves its dock or place of mooring. The regulations also

state that this watch on Channel 16 (156.800 MHz.) shall not be terminated

until the vessel is securely anchored or moored. There are precautions that

must be observed when using radiotelephone equipment while a vessel is in

port or navigating near coast stations. The regulations governing the use

of the transceivers in and around ports and coast stations state that the

VHF transceiver will be used in the 1-watt position.

Radio Logs

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