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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 comprises 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.


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.


Press To Transmit - PTT or “PRESSEL” switch is usually mounted on one side of the microphone or in the middle of the handgrip of a telephone style handset connected to the marine radio communication equipment. To operate correctly, you have to press it in order to switch the radio from receive mode to transmit mode and release it in order to revert to receive mode.


Radio Telephony - Radio communication known as RT uses a Tx (radio transmitter) to send out radio waves of a certain frequency and a Rx (radio receiver) to receive the radio waves at the same frequency. Radio waves consist of electro-magnetic energy in specific frequency bands within the radio frequency spectrum. Frequency of waves means the number of occurrences of a wave per second. For example, marine VHF RT works in the VHF part of the marine radio frequency spectrum, which extends between 156 MHz to 174 MHz.


radio receiver


Search And Rescue - SAR is an operation mounted by emergency services, often well-trained volunteers, to find someone believed to be in distress, lost, sick or injured at sea, whether close to shore or not.


Search and Rescue Satellite-Aided Tracking


Search and Rescue [Radar] Transponder - It is a portable device, which is used as a complimentary distress alerting system. It enables any ship/airplane/helicopter in the area to locate survivors easily by just the use of their proper radar system.


Simplex is the communication method where both transmitter and receiver are operating on a single (or the same) frequency. On simplex channels it isn't possible to transmit and receive simultaneously. Simplex channels are mainly used for Distress, Urgency, Safety and Routine Calling purposes, port, pilotage, harbour and inter-ship operations.

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