The United States Coast Guard maintains radio stations for communication between Coast Guard units, Coast Guard units and other government entities, and Coast Guard units and the general public. Most communications take place on the VHF marine bands. For long-range communications with aircraft, Coast Guard stations use shortwavesingle-sideband communications. Weather and safety of navigation forecasts involve facsimile as well as other modes over shortwave and mediumwave transmissions.
According to the NTIA, the Coast Guard is the seventh-biggest user of radio spectrum in the United States. The U.S. Coast Guard maintains a network of VHF radio stations at its shore stations and on cutters and boats, as well as stations of the U.S. Coast Guard Auxiliary. In addition, the Coast Guard maintains a chain of high frequency (HF) and medium frequency (MF) radio stations that provide communications in the Atlantic and Pacific oceans, the Gulf of Mexico, and the Caribbean Sea. Coast Guard VHF Radio stations are currently being upgraded through the Rescue 21 program to meet the US obligations under the Global Maritime Distress Safety System.
History of Coast Guard shore stations
The first Coast Guard shore stations were established after 1924, when the Coast Guard's mission expanded. The first shore station was at Rockaway Point Coast Guard Station, located at Fort Tilden, New York; and the network expanded to Nahant, Massachusetts; New London, Connecticut; Cape May, New Jersey; Cape Henry, Virginia (with the call sign NMN); Fernandina, Florida; Fort Lauderdale, Florida; Mobile, Alabama; San Francisco, California; San Pedro, California; Port Angeles, Washington; and Anacortes, Washington in the 1930s.
The network expanded even further in the 1940s, adding radio station NMH in Washington, D.C, among others. However, in the 1970s, the increasing use of automation caused the number of stations to contract. In 1976, for example, NMN (then at Communication Station (COMMSTA) Portsmouth) assumed the duties of NMH in Washington, and took over remote operations from Miami in 1993, Boston (NMF) in 1996, and New Orleans in 1998.
With the introduction of the computer-assisted Rescue 21 system, the ability of the Coast Guard to provide coverage on the marine VHF band in marginal areas has increased.
Current Assignments
The Coast Guard radio stations are centrally operated from the Communications Command (COMMCOM). The COMMCOM is located on the U.S. Navy Support Agency Northwest Annex in Chesapeake, Virginia. The COMMCOM has a staff of approximately 100 people that execute contingency communications, conduct communications training aboard Coast Guard cutters, and operate the following stations:
RCF New Orleans, Louisiana: call sign NMG (remotely)
RCF Point Reyes, California: call sign NMC (remotely)
RCF Honolulu, HI: call sign NMO (remotely)
RCF Kodiak, AK: call sign NOJ (remotely)
Modes of transmission
These stations broadcast navigation and marine safety messages through several means, including Navigational Telex [NAVTEX] transmissions on 518kHz; facsimile transmissions of National Weather Service charts; single sideband transmissions; and Simplex Teletype Over Radio SITOR narrow-band direct-printing broadcasts. In the 1960s through the 1980s, these transmissions were broadcast live, with the interval signal of "Semper Paratus"; however, now, using Voice Broadcast Automation (VOBRA), a computerized voice ("Perfect Paul") reads the voice messages.
NAVTEX transmissions are identified by the last letter of the callsign of the station. Each station transmits a NAVTEX broadcast six times a day, including two rebroadcasts of the general forecast. A NAVTEX broadcast includes maritime navigation warnings, weather forecasts, ice warnings, Gulf Stream locations, radio navigation information, rescue messages, and marine advisories. Each station has 2 NAVTEX transmitters.
Besides broadcast messages, Coast Guard stations handle direct traffic between aircraft, cutters, boats, and shore stations on VHF, MF, and HF frequencies, including the HF Data Link encrypted e-mail system and Digital Selective Calling (DSC), which uses radio telephone to send digitally encrypted signals to either one receiver or a group or receivers.
Coast Guard Auxiliary stations are privately owned stations that have been offered for use of the Government and have been approved by the Coast Guard. They may be on the marine VHF band or use HF communications. In addition, many Coast Guard Auxiliarists are qualified radio watchstanders at existing Coast Guard stations.
Coast Guard call signs
Most Coast Guard land-based VHF radio stations do not use three-letter call signs as the larger communications stations do; instead, they identify themselves by the activity name, such as "Sector Baltimore", "Station Washington, D.C. (or Station Washington)". All Cutters (CG vessels 65 feet in length or greater) have four-letter international radio call signs, such as USCGC Citrus/NRPQ. Cutters normally identify themselves as "Cutter (name)". Boats identify themselves with the last digits of their registration number, for example, a Defender-class boat with the registration 25123 would be "Coast Guard 25123, while a 41-foot boat would be "Coast Guard 41345." Aircraft identify themselves by their number. A number beginning with "15,17,20" is a HC-130; "21" is a HU-25A/C/D; "23" is a HC-144A; "60" is a MH/HH-60J/T helicopter; "65 or 66" is a HH/MH-65; . Auxiliary aircraft and ships identify themselves as "Auxiliary ###".
Very high frequency (VHF) is the ITU designation for the range of radio frequency electromagnetic waves from 30 to 300 megahertz (MHz), with corresponding wavelengths of ten meters to one meter. Frequencies immediately below VHF are denoted high frequency (HF), and the next higher frequencies are known as ultra high frequency (UHF).
Medium frequency (MF) is the ITU designation for radio frequencies (RF) in the range of 300 kilohertz (kHz) to 3 megahertz (MHz). Part of this band is the medium wave (MW) AM broadcast band. The MF band is also known as the hectometer band as the wavelengths range from ten to one hectometers. Frequencies immediately below MF are denoted as low frequency (LF), while the first band of higher frequencies is known as high frequency (HF). MF is mostly used for AM radio broadcasting, navigational radio beacons, maritime ship-to-shore communication, and transoceanic air traffic control.
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, 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, inclusive, designated by the International Telecommunication Union 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. Transmitter power is limited to 25 watts, giving them a range of about 100 kilometres.
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.
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NAVTEX, sometimes styled Navtex or NavTex, is an international automated medium frequency direct-printing service for delivery of navigational and meteorological warnings and forecasts, as well as urgent maritime safety information (MSI) to ships.
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.
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In broadcasting and radio communications, a call sign is a unique identifier for a transmitter station. A call sign can be formally assigned by a government agency, informally adopted by individuals or organizations, or even cryptographically encoded to disguise a station's identity.
The High Frequency Global Communications System (HFGCS) is a network of single sideband shortwave transmitters of the United States Air Force which is used to communicate with aircraft in flight, ground stations and some United States Navy surface assets. All worldwide receiving and transmitting sites in the HFGCS system are remotely controlled from Andrews Air Force Base and Grand Forks Air Force Base. Before 1 October 2002 it was known as the Global High Frequency System (GHFS).
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 weather reports being interrupted by emergency weather reports whenever needed. Weather radios are typically equipped with a standby alerting function—if the radio is muted or tuned to another band and a severe weather bulletin is transmitted, it can automatically sound an alarm and/or switch to a pre-tuned weather channel for emergency weather information. Weather radio services may also occasionally broadcast non-weather-related emergency information, such as in the event of a natural disaster, a child abduction alert, or a terrorist attack.
2182 kHz is a radio frequency designed exclusively for distress calls and related calling operations in the maritime service.
An international distress frequency is a radio frequency that is designated for emergency communication by international agreement.
The Response Boat – Medium (RB-M) is a 45-foot (14 m) utility boat used by the United States Coast Guard. It is a replacement for the Coast Guard's retired fleet of 41-foot (12 m) utility boats (UTB), which had been in use by the Coast Guard since the 1970s. On June 21, 2006 the USCG awarded the RB-M contract to Marinette Marine of Marinette, Wisconsin and Kvichak Marine Industries of Seattle, Washington. The RB-M was designed by Camarc Design in the UK. Between June of 2006 and March of 2015 Marinette, in Green Bay Wisconsin and Kvichak in Kent, Washington partnered to build and deliver 174 RB-Ms to the USCG. Kvichak developed and delivered several police boat variants to several cities including Seattle and New York.
The Directorate General of Coastal Safety has been established by the Turkish Republic Council Of Ministers’ decision on 12 May 1997 as a General Directorate and State owned Organization. The mission of the foundation is to assist and improve the safety of navigation in Turkish Waters. The organization’s core competences are:
Maritime call signs are call signs assigned as unique identifiers to ships and boats. All radio transmissions must be individually identified by the call sign. Merchant and naval vessels are assigned call signs by their national licensing authorities.
The following January 2019 order of battle is for the United States Coast Guard.
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