Long Range Certificate Course

Maritime Mobile Service Identity - MMSI is a unique 9 digit number and acts in the same way as a telephone number. The MMSI allows the radio operator to make automatic calls through VHF DSC radio and is the identity that is automatically transmitted within DSC calls. These MMSI numbers are issued by the appropriate authorities in the country of registration of the vessel and can be referenced back to a database of information about the vessel and its owners and so forth.

Maritime Rescue and Coordination Centre - All SAR activities are organized by MRCCs and MRSCs within specified navigational sea areas normally bordering their coastlines.

Maritime Rescue Sub Centres - All SAR activities are organized by MRCCs and MRSCs within specified navigational sea areas normally bordering their coastlines.

Maritime Safety Information - Navigational and meteorological warnings, meteorological forecasts, and other urgent safety-related information broadcast to ships.

Maximum Usable Frequency is the frequency at which radio communications just starts to fail. It is caculated by formula: MUF=f0/cos alpha where is
h= layer height
f0= layer density
alpha = arc tg ((d/2)/h)

NAVigational AREA - Under the WWNWS the world's oceans are divided into 16 geographical sea areas called NAVAREAs, which are identified by Roman numerals and comprise NAVTEX CRS identified by a single letter of the alphabet from A to Z.

NAVigational TELex - It is a system for transmitting MSI in GMDSS Sea Area A1 and A2.

Narrow Band Direct Printing

NCS Network Co-ordination Station. This is the land earth station within the Inmarsat Oceanan Region which is responsible for a smooth communication process. This station directs the mobile users and the Land Earth Stations to the right appointed channel.

Nautical Mile - A nautical mile or sea mile is a unit of length. It corresponds approximately to one minute of latitude along any meridian. The international standard definition is: 1 NM = 1,852 m exactly.