Marine VHF
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Marine VHF radio is a worldwide system of two way radio transceivers on ships and watercraft used for bidirectional voice communication from ship-to-ship, ship-to-shore (for example with
harbormaster A harbourmaster (or harbormaster, see spelling differences) is an official responsible for enforcing the regulations of a particular harbour or port, in order to ensure the safety of navigation, the security of the harbour and the correct opera ...
s), and in certain circumstances ship-to-aircraft. It uses FM channels in the very high frequency (VHF) radio band in the frequency range between 156 and 174 
MHz The hertz (symbol: Hz) is the unit of frequency in the International System of Units (SI), often described as being equivalent to one event (or cycle) per second. The hertz is an SI derived unit whose formal expression in terms of SI base u ...
, designated by the
International Telecommunication Union The International Telecommunication Union (ITU)In the other common languages of the ITU: * * is a list of specialized agencies of the United Nations, specialized agency of the United Nations responsible for many matters related to information ...
as the ''VHF maritime mobile band''. In some countries additional channels are used, such as the L and F channels for leisure and fishing vessels in the Nordic countries (at 155.5–155.825 MHz). Transmitter power is limited to 25 watts, giving them a range of about . Marine VHF radio equipment is installed on all large ships and most seagoing small craft. It is also used, with slightly different regulation, on rivers and lakes. It is used for a wide variety of purposes, including
marine navigation Marine navigation is the art and science of steering a ship from a starting point (sailing) to a destination, efficiently and responsibly. It is an art because of the skill that the navigator must have to avoid the dangers of navigation, and it ...
and traffic control, summoning
rescue Rescue comprises responsive operations that usually involve the saving of life, removal from danger, liberation from restraint, or the urgent treatment of injury, injuries after an incident. It may be facilitated by a range of tools and equipm ...
services and communicating with
harbour A harbor (American English), or harbour (Commonwealth English; see American and British English spelling differences#-our, -or, spelling differences), is a sheltered body of water where ships, boats, and barges can be Mooring, moored. The t ...
s, locks,
bridge A bridge is a structure built to Span (engineering), span a physical obstacle (such as a body of water, valley, road, or railway) without blocking the path underneath. It is constructed for the purpose of providing passage over the obstacle, whi ...
s and
marina A marina (from Spanish , Portuguese and Italian : "related to the sea") is a dock or basin with moorings and supplies for yachts and small boats. A marina differs from a port in that a marina does not handle large passenger ships or cargo ...
s.


Background

Marine radio was the first commercial application of
radio Radio is the technology of communicating using radio waves. Radio waves are electromagnetic waves of frequency between 3  hertz (Hz) and 300  gigahertz (GHz). They are generated by an electronic device called a transmitter connec ...
technology, allowing ships to keep in touch with shore and other ships, and send out a distress call for rescue in case of emergency.
Guglielmo Marconi Guglielmo Giovanni Maria Marconi, 1st Marquess of Marconi ( ; ; 25 April 1874 – 20 July 1937) was an Italian electrical engineer, inventor, and politician known for his creation of a practical radio wave-based Wireless telegraphy, wireless tel ...
invented radio communication in the 1890s, and the Marconi Company installed
wireless telegraphy Wireless telegraphy or radiotelegraphy is the transmission of text messages by radio waves, analogous to electrical telegraphy using electrical cable, cables. Before about 1910, the term ''wireless telegraphy'' was also used for other experimenta ...
stations on ships beginning around 1900. Marconi built a string of shore stations and in 1904 established the first
Morse code Morse code is a telecommunications method which Character encoding, encodes Written language, text characters as standardized sequences of two different signal durations, called ''dots'' and ''dashes'', or ''dits'' and ''dahs''. Morse code i ...
distress call, the letters
CQD CQD (transmitted in Morse code as ) is one of the first distress signals adopted for radio use. On 7 January 1904 the Marconi International Marine Communication Company issued "Circular 57", which specified that, for the company's in ...
, used until 1906 when SOS was agreed on. The first significant marine rescue due to radio was the 1909 sinking of the luxury liner RMS ''Republic'', in which 1,500 lives were saved. This and the 1912 rescue brought the field of marine radio to public consciousness, and marine radio operators were regarded as heroes. By 1920, the US had a string of 12 coastal stations stretched along the Atlantic seaboard from
Bar Harbor, Maine Bar Harbor () is a resort town on Mount Desert Island in Hancock County, Maine, United States. As of the 2020 census, its population is 5,089. The town is home to the College of the Atlantic, Jackson Laboratory, and MDI Biological Laborat ...
to
Cape May, New Jersey Cape May (sometimes Cape May City) is a City (New Jersey), city and seaside resort located at the southern tip of Cape May Peninsula in Cape May County, New Jersey, Cape May County in the U.S. state of New Jersey. Located on the Atlantic Ocean ...
. The first marine radio transmitters used the
longwave In radio, longwave (also spelled long wave or long-wave and commonly abbreviated LW) is the part of the radio spectrum with wavelengths longer than what was originally called the medium-wave (MW) broadcasting band. The term is historic, dati ...
bands. During World War I
amplitude modulation Amplitude modulation (AM) is a signal modulation technique used in electronic communication, most commonly for transmitting messages with a radio wave. In amplitude modulation, the instantaneous amplitude of the wave is varied in proportion t ...
was developed, and in the 1920s spark radiotelegraphy equipment was replaced by
vacuum tube A vacuum tube, electron tube, thermionic valve (British usage), or tube (North America) is a device that controls electric current flow in a high vacuum between electrodes to which an electric voltage, potential difference has been applied. It ...
radiotelephony A radiotelephone (or radiophone), abbreviated RT, is a radio communication system for conducting a conversation; radiotelephony means telephony by radio. It is in contrast to ''radiotelegraphy'', which is radio transmission of telegrams (messag ...
allowing voice communication. Also in the 1920s, the ionospheric skip or
skywave In radio communication, skywave or skip refers to the propagation of radio waves reflected or refracted back toward Earth from the ionosphere, an electrically charged layer of the upper atmosphere. Since it is not limited by the curvatur ...
phenomenon was discovered, which allowed lower power vacuum tube transmitters operating in the
shortwave Shortwave radio is radio transmission using radio frequencies in the shortwave bands (SW). There is no official definition of the band range, but it always includes all of the high frequency band (HF), which extends from 3 to 30 MHz (app ...
bands to communicate at long distances. Hoping to foil German detection during the World War II Battle of the Atlantic, American and British convoy escorts used Talk-Between-Ships (TBS) radios operating on VHF.


Types of equipment

Sets can be fixed or portable. A fixed set generally has the advantages of a more reliable power source, higher transmit power, a larger and more effective antenna and a bigger display and buttons. A portable set (often essentially a waterproof, VHF
walkie-talkie A walkie-talkie, more formally known as a handheld transceiver, HT, or handheld radio, is a hand-held, portable, two-way radio transceiver. Its development during the Second World War has been variously credited to Donald Hings, radio engineer A ...
in design) can be carried on a kayak, or to a lifeboat in an emergency, has its own power source and is waterproof if
GMDSS The Global Maritime Distress and Safety System (GMDSS) is a worldwide system for automated emergency signal communication for ships at sea developed by the United Nations' International Maritime Organization (IMO) as part of the SOLAS Convention. ...
-approved. A few portable VHFs are even approved to be used as emergency radios in environments requiring intrinsically safe equipment (e.g. gas tankers, oil rigs, etc.).


Voice-only

Voice only equipment is the traditional type, which relies totally on the human voice for calling and communicating. Many lower priced handheld units are voice only as well as older fixed units.


Digital selective calling

DSC equipment, a part of the
Global Maritime Distress Safety System The Global Maritime Distress and Safety System (GMDSS) is a worldwide system for automated emergency signal communication for ships at sea developed by the United Nations' International Maritime Organization (IMO) as part of the SOLAS Convention. ...
(GMDSS), provides all the functionality of voice-only equipment and, additionally, allows several other features: * The ability to call another vessel using a unique identifier known as a
Maritime Mobile Service Identity A Maritime Mobile Service Identity (MMSI) is effectively a maritime object's international ''maritime telephone number'', a temporarily assigned UID issued by that object's current flag state (unlike an IMO number, which is a permanent global UID ...
(MMSI). This information is carried digitally and the receiving set will alert the operator of an incoming call once its own MMSI is detected. Calls are set up on the dedicated VHF channel 70 which DSC equipment must listen on continuously. The actual voice communication then takes place on a different channel specified by the caller. * A distress button, which automatically sends a digital distress signal identifying the calling vessel and the nature of the emergency * A built in
GPS receiver A satellite navigation (satnav) device or GPS device is a device that uses satellites of the Global Positioning System (GPS) or similar global navigation satellite systems (GNSS). A satnav device can determine the user's geographic coordinat ...
or facility to connect an external GPS receiver so that the user's location may be transmitted automatically along with a distress call. When a DSC radio is bought new the user will get the opportunity to program it with the MMSI number of the ship it is intended to be used on. However to change the MMSI after the initial programming can be problematic and require special proprietary tools. This is allegedly done to prevent theft.


Automatic identification system

More advanced transceiver units support AIS. This relies on a GPS receiver built into the VHF equipment or an externally connected one by which the transceiver obtains its position and transmits this information along with some other details about the ship (MMSI, cargo, draught, destination and some others) to nearby ships. AIS operates as a
mesh network A mesh network is a local area network topology in which the infrastructure nodes (i.e. bridges, switches, and other infrastructure devices) connect directly, dynamically and non-hierarchically to as many other nodes as possible and cooperate wit ...
and full featured units relay AIS messages from other ships, greatly extending the range of this system; however some low-end units are receive only or do not support the relaying functionality. AIS data is carried on dedicated VHF channels 87B and 88B at a
baud rate In a digitally modulated signal or a line code, symbol rate, modulation rate or baud is the number of symbol changes, waveform changes, or signaling events across the transmission medium per unit of time. The symbol rate is measured in ''baud'' ...
of 9,600bit/s using
GMSK In digital modulation, minimum-shift keying (MSK) is a type of continuous-phase frequency-shift keying that was developed in the late 1950s by Collins Radio employees Melvin L. Doelz and Earl T. Heald. Similar to OQPSK, MSK is encoded with bit ...
modulation and uses a form of time-division multiplexing.


Text messaging

Using the RTCM 12301.1 standard it is possible to send and receive text messages in a similar fashion to
SMS Short Message Service, commonly abbreviated as SMS, is a text messaging service component of most telephone, Internet and mobile device systems. It uses standardized communication protocols that let mobile phones exchange short text messages, t ...
between marine VHF transceivers which comply with this standard. However, as of 2019 very few transceivers support this feature. The recipient of the message needs to be tuned to the same channel as the transmitting station in order to receive it.


Regulation

In the United States, any person can legally purchase a Marine VHF radio and use it to communicate without requiring any special license as long as they abide by certain rules, but in a great many other countries a license is required to transmit on Marine VHF frequencies. In the United Kingdom and
Ireland Ireland (, ; ; Ulster Scots dialect, Ulster-Scots: ) is an island in the North Atlantic Ocean, in Northwestern Europe. Geopolitically, the island is divided between the Republic of Ireland (officially Names of the Irish state, named Irelan ...
and some other European countries both the operator and the equipment must be separately licensed. A ''
Short Range Certificate The Short Range Certificate is an internationally valid certificate issued to marine radio station operators. It entitles the holder to participate in marine communications on leisure crafts using Marine VHF radio and DSC (Digital Selective Calli ...
'' is the minimum requirement to use an installed marine VHF radio. This is usually obtained after completing a course of around two days and passing an exam. This is intended for those operating on lakes and in coastal areas whereas a '' Long Range Certificate'' is usually recommended for those operating further out as it also covers HF and MF radios as well as
INMARSAT Inmarsat is a British communications satellite, satellite telecommunications company, offering global mobile services. It provides telephone and data services to users worldwide, via portable or mobile terminals which communicate with groun ...
systems. Installations fixed on a particular vessel require a Ship Radio License. Portable equipment that could be used in multiple craft, dinghys etc. required a Ship Portable Radio Licence.


Automatic Transmitter Identification System (marine)

For use on the inland waterways within continental Europe, a compulsory Automatic Transmitter Identification System (ATIS) transmission conveys the vessel's identity after each voice transmission. This is a ten-digit code that is either an encoded version of the ship's alphanumeric call sign, or for vessels from outside the region, the ship MMSI prefixed with "9". The requirement to use ATIS in Europe, and which VHF channels may be used, are strongly regulated, most recently by the Basel agreements.


Channels and frequencies

A marine VHF set is a combined transmitter and receiver and only operates on standard, international frequencies known as
channels Channel, channels, channeling, etc., may refer to: Geography * Channel (geography), a landform consisting of the outline (banks) of the path of a narrow body of water. Australia * Channel Country, region of outback Australia in Queensland and pa ...
. Channel 16 (156.8 MHz) is the international calling and distress channel. Transmission power ranges between 1 and 25 watts, giving a maximum range of up to about 60
nautical mile A nautical mile is a unit of length used in air, marine, and space navigation, and for the definition of territorial waters. Historically, it was defined as the meridian arc length corresponding to one minute ( of a degree) of latitude at t ...
s (111 km) between aerials mounted on tall ships and hills, and between aerials mounted on small
boat A boat is a watercraft of a large range of types and sizes, but generally smaller than a ship, which is distinguished by its larger size or capacity, its shape, or its ability to carry boats. Small boats are typically used on inland waterways s ...
s at sea level.
Frequency modulation Frequency modulation (FM) is a signal modulation technique used in electronic communication, originally for transmitting messages with a radio wave. In frequency modulation a carrier wave is varied in its instantaneous frequency in proporti ...
(FM) is used, with vertical polarization, meaning that antennas have to be vertical in order to have good reception. For longer range communication at sea, marine MF and marine HF bands and
satellite phone A satellite telephone, satellite phone or satphone is a type of mobile phone that connects to other phones or the telephone network by radio link through satellites orbiting the Earth instead of terrestrial cell sites, as cellphones do. Therefo ...
s can be used. Half-duplex channels here are listed with the A and B frequencies the same. The frequencies, channels, and some of their purposes are governed by the
ITU The International Telecommunication Union (ITU)In the other common languages of the ITU: * * is a specialized agency of the United Nations responsible for many matters related to information and communication technologies. It was established ...
. For an authoritative list see. The original allocation of channels consisted of only channels 1 to 28 with 50 kHz spacing between channels, and the second frequency for full-duplex operation 4.6 MHz higher. Improvements in radio technology later meant that the channel spacing could be reduced to 25 kHz with channels 60 to 88 interspersed between the original channels. Channels 75 and 76 are omitted as they are either side of the calling and distress channel 16, acting as guard channels. The frequencies which would have been the second frequencies on half-duplex channels are not used for marine purposes and can be used for other purposes that vary by country. For example, 161.000 to 161.450 MHz are part of the allocation to the
Association of American Railroads The Association of American Railroads (AAR) is an industry trade group representing primarily the major freight Rail transport, railroads of North America (Canada, Mexico and the United States). Amtrak and some regional Commuter rail in North Am ...
channels used by railways in the US and Canada.


Operating procedure

Marine VHF mostly uses
half-duplex A duplex communication system is a point-to-point system composed of two or more connected parties or devices that can communicate with one another in both directions. Duplex systems are employed in many communications networks, either to allow ...
audio equipment and non-relayed transmissions. Ship to ship communication is over a single radio frequency (
simplex In geometry, a simplex (plural: simplexes or simplices) is a generalization of the notion of a triangle or tetrahedron to arbitrary dimensions. The simplex is so-named because it represents the simplest possible polytope in any given dimension. ...
), while ship to shore often uses
full duplex A duplex communication system is a point-to-point system composed of two or more connected parties or devices that can communicate with one another in both directions. Duplex systems are employed in many communications networks, either to allow ...
frequency pairs, however the transceivers are usually half-duplex devices that cannot receive when transmitting even on a full-duplex channel. To transmit the user presses a "
push to talk Push-to-talk (PTT), also known as press-to-transmit, is a method of having conversations or talking on half-duplex communication lines, including two-way radio, using a momentary button to switch from voice reception mode to transmit mode. ...
" button on the set or microphone which turns the transmitter on and the receiver off in a device with half-duplex audio, even on a full-duplex radio channel; on devices with full-duplex audio the receiver is left on while transmitting on a full-duplex radio channel. Communication can take place in both directions simultaneously on full-duplex channels when the equipment on both ends allows it. Full duplex channels can be used to place calls over the public
telephone network A telephone network is a telecommunications network that connects telephones, which allows telephone calls between two or more parties, as well as newer features such as fax and internet. The idea was revolutionized in the 1920s, as more and more ...
for a fee via a marine operator. When equipment supporting full-duplex audio is used, the call is similar to one using a mobile phone or landline. When half-duplex is used, voice is only carried one way at a time and the party on the boat must press the transmit button only when speaking. This facility is still available in some areas, though its use has largely died out with the advent of mobile and satellite phones. Marine VHF radios can also receive
weather radio A weather radio is a specialized radio receiver that is designed to receive a public broadcast service, typically from government-owned radio stations, dedicated to broadcasting weather forecasts and reports on a continual basis, with the routine w ...
broadcasts, where they are available. The accepted conventions for use of marine radio are collectively termed "proper operating procedure". These international conventions include: * Stations should listen for 30 seconds before transmitting and not interrupt other stations. * Maintaining a watch listening on Channel 16 when not otherwise using the radio. All calls are established on channel 16, except for distress working switch to a working ship-to-ship or ship-to-shore channel. (procedure varies in the U.S. only when calls can be established on Ch. 9) * During distress operations silence maintained on ch. 16 for other traffic until the channel is released by the controlling station using the pro-word "Silence Fini". If a station does use Ch. 16 during distress operations controlling station issues the command "silence mayday". * Using a set of international "calling" procedures such as the "
Mayday Mayday is an emergency procedure word used internationally as a distress signal in voice-procedure radio communications. It is used to signal a life-threatening emergency primarily by aviators and mariners, but in some countries local organiz ...
" distress call, the "
Pan-pan The radiotelephony message PAN-PAN is the international standard urgency signal that someone aboard a boat, ship, aircraft, or other vehicle uses to declare that they need help and that the situation is urgent, but for the time being, does not po ...
" urgency call and "
Sécurité Sécurité (; French: ''sécurité'') (often repeated thrice, "Sécurité, sécurité, sécurité") is a procedure word used in the maritime radio service that warns the crew that the following message is important safety information. The most com ...
" navigational hazard call. * Using " pro-words" based on the
English language English is a West Germanic language that developed in early medieval England and has since become a English as a lingua franca, global lingua franca. The namesake of the language is the Angles (tribe), Angles, one of the Germanic peoples th ...
such as ''Acknowledge, All after, All before, All stations, Confirm, Correct, Correction, In figures, In letters, Over, Out, Radio check, Read back, Received, Say again, Spell, Standby, Station calling, This is, Wait, Word after, Word before, Wrong'' (local language is used for some of these, when talking to local stations) * Using the
NATO phonetic alphabet The International Radiotelephony Spelling Alphabet or simply the Radiotelephony Spelling Alphabet, commonly known as the NATO phonetic alphabet, is the most widely used set of clear-code words for communicating the letters of the Latin/Roman ...
: ''Alfa, Bravo, Charlie, Delta, Echo, Foxtrot, Golf, Hotel, India, Juliett, Kilo, Lima, Mike, November, Oscar, Papa, Quebec, Romeo, Sierra, Tango, Uniform, Victor, Whiskey, X-ray, Yankee, Zulu'' * Using a phonetic numbering system based on the
English language English is a West Germanic language that developed in early medieval England and has since become a English as a lingua franca, global lingua franca. The namesake of the language is the Angles (tribe), Angles, one of the Germanic peoples th ...
or a combination of English and Roman languages: ''Wun, Too, Tree, Fow-er, Fife, Six, Sev-en, Ait, Nin-er, Zero, Decimal''; alternatively in marine communication: ''unaone, bissotwo, terrathree, kartefour, pantafive, soxisix, setteseven, oktoeight, novenine, nadazero'' Slightly adjusted regulations can apply for inland shipping, such as the
Basel rules Basel ( ; ), also known as Basle ( ), ; ; ; . is a city in northwestern Switzerland on the river Rhine (at the transition from the High to the Upper Rhine). Basel is Switzerland's third-most-populous city (after Zurich and Geneva), with 17 ...
( :de:Regionale Vereinbarung über den Binnenschifffahrtsfunk) in Western Europe.


Future

In 2022, the
ETSI The European Telecommunications Standards Institute (ETSI) is an independent, not-for-profit, standardization organization operating in the field of Information and communications technology, information and communications. ETSI supports the de ...
issued a proposal for implementing the use of
FDMA Frequency-division multiple access (FDMA) is a channel access method used in some multiple-access protocols. FDMA allows multiple users to send data through a single communication channel, such as a coaxial cable or microwave beam, by dividing ...
protocols on the band in response to increasingly scarce availability of voice channels in some circumstances owing to the widespread use of systems such as AIS. The plan includes significantly narrower 6.25 kHz channel spacing, and would support voice and data applications.


See also

*
2182 kHz 2182  kHz is a radio frequency designed exclusively for distress calls and related calling operations – Mostly historical information for dates prior to February 2009. in the maritime service. It is equivalent to a wavelength of 137.4 ...
*
Automated Maritime Telecommunications System Automated Maritime Telecommunications System (AMTS) is a commercial mobile radio service used within the United States. It operates within the VHF frequency range, just above the North American Band III television range, and offers both voice and ...
* Maritime mobile amateur radio *
Radio horizon Line-of-sight propagation is a characteristic of electromagnetic radiation or acoustic wave propagation which means waves can only travel in a direct visual path from the source to the receiver without obstacles. Electromagnetic transmission incl ...
* Ship-to-shore


References


External links


US Coast Guard basic radio information for boatersCoast Guard marine channel listing (with frequencies)
**

* {{Telecommunications Navigational equipment Maritime communication Rescue equipment Marine electronics fr:Bandes marines#Bande VHF