LORAN
Overview
 
LORAN is a terrestrial radio navigation
Radio navigation
Radio navigation or radionavigation is the application of radio frequencies to determine a position on the Earth. Like radiolocation, it is a type of radiodetermination.The basic principles are measurements from/to electric beacons, especially...

 system using low frequency
Low frequency
Low frequency or low freq or LF refers to radio frequencies in the range of 30 kHz–300 kHz. In Europe, and parts of Northern Africa and of Asia, part of the LF spectrum is used for AM broadcasting as the longwave band. In the western hemisphere, its main use is for aircraft beacon,...

 radio transmitters in multiple deployment (multilateration
Multilateration
Multilateration is a navigation technique based on the measurement of the difference in distance to two or more stations at known locations that broadcast signals at known times. Unlike measurements of absolute distance or angle, measuring the difference in distance results in an infinite number of...

) to determine the location
Location (geography)
The terms location and place in geography are used to identify a point or an area on the Earth's surface or elsewhere. The term 'location' generally implies a higher degree of can certainty than "place" which often has an ambiguous boundary relying more on human/social attributes of place identity...

 and speed of the receiver.

The most recent version of LORAN in use is LORAN-C, which operates in the low frequency portion of the electromagnetic spectrum
Electromagnetic spectrum
The electromagnetic spectrum is the range of all possible frequencies of electromagnetic radiation. The "electromagnetic spectrum" of an object is the characteristic distribution of electromagnetic radiation emitted or absorbed by that particular object....

 from 90 to 110 Kilohertz. Many nations have used the system, including the United States
United States
The United States of America is a federal constitutional republic comprising fifty states and a federal district...

, Japan
Japan
Japan is an island nation in East Asia. Located in the Pacific Ocean, it lies to the east of the Sea of Japan, China, North Korea, South Korea and Russia, stretching from the Sea of Okhotsk in the north to the East China Sea and Taiwan in the south...

, and several European countries. Russia uses a nearly identical system in the same frequency range, called CHAYKA
CHAYKA
Chayka is a Russian terrestrial radio navigation system, similar to LORAN-C. It is also run on 100 kHz and is described like LORAN-C by its GRI.-Chayka-Chains:There are 5 Chayka-chains in use:...

.

LORAN use has been in steep decline, with the satellite based Global Positioning System
Global Positioning System
The Global Positioning System is a space-based global navigation satellite system that provides location and time information in all weather, anywhere on or near the Earth, where there is an unobstructed line of sight to four or more GPS satellites...

 (GPS) being the primary replacement.
Encyclopedia
LORAN is a terrestrial radio navigation
Radio navigation
Radio navigation or radionavigation is the application of radio frequencies to determine a position on the Earth. Like radiolocation, it is a type of radiodetermination.The basic principles are measurements from/to electric beacons, especially...

 system using low frequency
Low frequency
Low frequency or low freq or LF refers to radio frequencies in the range of 30 kHz–300 kHz. In Europe, and parts of Northern Africa and of Asia, part of the LF spectrum is used for AM broadcasting as the longwave band. In the western hemisphere, its main use is for aircraft beacon,...

 radio transmitters in multiple deployment (multilateration
Multilateration
Multilateration is a navigation technique based on the measurement of the difference in distance to two or more stations at known locations that broadcast signals at known times. Unlike measurements of absolute distance or angle, measuring the difference in distance results in an infinite number of...

) to determine the location
Location (geography)
The terms location and place in geography are used to identify a point or an area on the Earth's surface or elsewhere. The term 'location' generally implies a higher degree of can certainty than "place" which often has an ambiguous boundary relying more on human/social attributes of place identity...

 and speed of the receiver.

The most recent version of LORAN in use is LORAN-C, which operates in the low frequency portion of the electromagnetic spectrum
Electromagnetic spectrum
The electromagnetic spectrum is the range of all possible frequencies of electromagnetic radiation. The "electromagnetic spectrum" of an object is the characteristic distribution of electromagnetic radiation emitted or absorbed by that particular object....

 from 90 to 110 Kilohertz. Many nations have used the system, including the United States
United States
The United States of America is a federal constitutional republic comprising fifty states and a federal district...

, Japan
Japan
Japan is an island nation in East Asia. Located in the Pacific Ocean, it lies to the east of the Sea of Japan, China, North Korea, South Korea and Russia, stretching from the Sea of Okhotsk in the north to the East China Sea and Taiwan in the south...

, and several European countries. Russia uses a nearly identical system in the same frequency range, called CHAYKA
CHAYKA
Chayka is a Russian terrestrial radio navigation system, similar to LORAN-C. It is also run on 100 kHz and is described like LORAN-C by its GRI.-Chayka-Chains:There are 5 Chayka-chains in use:...

.

LORAN use has been in steep decline, with the satellite based Global Positioning System
Global Positioning System
The Global Positioning System is a space-based global navigation satellite system that provides location and time information in all weather, anywhere on or near the Earth, where there is an unobstructed line of sight to four or more GPS satellites...

 (GPS) being the primary replacement. However, there have been attempts to enhance and re-popularize LORAN, mainly to serve as a backup and land-based alternative to GPS and other Global navigation satellite system
Global Navigation Satellite System
A satellite navigation or SAT NAV system is a system of satellites that provide autonomous geo-spatial positioning with global coverage. It allows small electronic receivers to determine their location to within a few metres using time signals transmitted along a line-of-sight by radio from...

 (GNSS) systems.

The current LORAN system has been phased out in the United States and Canada. The United States Coast Guard
United States Coast Guard
The United States Coast Guard is a branch of the United States Armed Forces and one of the seven U.S. uniformed services. The Coast Guard is a maritime, military, multi-mission service unique among the military branches for having a maritime law enforcement mission and a federal regulatory agency...

 (USCG) and Canadian Coast Guard
Canadian Coast Guard
The Canadian Coast Guard is the coast guard of Canada. It is a federal agency responsible for providing maritime search and rescue , aids to navigation, marine pollution response, marine radio, and icebreaking...

 (CCG) ceased transmitting LORAN-C (and joint CHAYKA) signals in 2010.

History

LORAN was an American development, advancing the technology of the British
United Kingdom
The United Kingdom of Great Britain and Northern IrelandIn the United Kingdom and Dependencies, other languages have been officially recognised as legitimate autochthonous languages under the European Charter for Regional or Minority Languages...

 GEE
GEE (navigation)
Gee was the code name given to a radio navigation system used by the Royal Air Force during World War II.Different sources record the name as GEE or Gee. The naming supposedly comes from "Grid", so the lower case form is more correct, and is the form used in Drippy's publications. See Drippy 1946....

 radio navigation
Radio navigation
Radio navigation or radionavigation is the application of radio frequencies to determine a position on the Earth. Like radiolocation, it is a type of radiodetermination.The basic principles are measurements from/to electric beacons, especially...

 system that was used early in World War II
World War II
World War II, or the Second World War , was a global conflict lasting from 1939 to 1945, involving most of the world's nations—including all of the great powers—eventually forming two opposing military alliances: the Allies and the Axis...

. While GEE had a range of about 400 miles (644 km), initial LORAN systems had a range of 1,200 miles (1,930 km). It originally was known as "LRN" for Loomis Radio Navigation, after Alfred Lee Loomis
Alfred Lee Loomis
Alfred Lee Loomis was an American attorney, investment banker, philanthropist, scientist/physicist, pioneer in military radar usages, inventor of the LORAN or Long Range Navigation System, and lifelong patron of scientific research...

, who invented the longer range system and played a crucial role in military research and development during World War II
World War II
World War II, or the Second World War , was a global conflict lasting from 1939 to 1945, involving most of the world's nations—including all of the great powers—eventually forming two opposing military alliances: the Allies and the Axis...

, but later was renamed to the abbreviation for the more descriptive term. LORAN systems were built during World War II after development at the Massachusetts Institute of Technology
Massachusetts Institute of Technology
The Massachusetts Institute of Technology is a private research university located in Cambridge, Massachusetts. MIT has five schools and one college, containing a total of 32 academic departments, with a strong emphasis on scientific and technological education and research.Founded in 1861 in...

 (MIT) Radiation Laboratory
Radiation Laboratory
The Radiation Laboratory, commonly called the Rad Lab, was located at the Massachusetts Institute of Technology in Cambridge, Massachusetts and functioned from October 1940 until December 31, 1945...

 and were used extensively by the US Navy and Royal Navy
Royal Navy
The Royal Navy is the naval warfare service branch of the British Armed Forces. Founded in the 16th century, it is the oldest service branch and is known as the Senior Service...

. The RAF also used LORAN on raids beyond the range of GEE.

In November 2009, the USCG
United States Coast Guard
The United States Coast Guard is a branch of the United States Armed Forces and one of the seven U.S. uniformed services. The Coast Guard is a maritime, military, multi-mission service unique among the military branches for having a maritime law enforcement mission and a federal regulatory agency...

 announced that LORAN-C is not needed by the U.S. for maritime navigation. This decision left the fate of LORAN and eLORAN in the U.S. to the Secretary of the Department of Homeland Security. Per a subsequent announcement, the U.S. Coast Guard, in accordance with the DHS Appropriations Act, terminated the transmission of all U.S. LORAN-C signals on February 8, 2010. On August 1, 2010 the U.S. transmission of the Russian American signal was terminated, and on August 3, 2010 all Canadian signals were shut down by the USCG and the CCG.

Principle

The navigational method
Multilateration
Multilateration is a navigation technique based on the measurement of the difference in distance to two or more stations at known locations that broadcast signals at known times. Unlike measurements of absolute distance or angle, measuring the difference in distance results in an infinite number of...

 provided by LORAN is based on measuring the time difference between the receipt of signals from a pair of radio
Radio
Radio is the transmission of signals through free space by modulation of electromagnetic waves with frequencies below those of visible light. Electromagnetic radiation travels by means of oscillating electromagnetic fields that pass through the air and the vacuum of space...

 transmitters. A given constant time difference between the signals from the two stations can be represented by a hyperbolic
Hyperbola
In mathematics a hyperbola is a curve, specifically a smooth curve that lies in a plane, which can be defined either by its geometric properties or by the kinds of equations for which it is the solution set. A hyperbola has two pieces, called connected components or branches, which are mirror...

 line of position (LOP).

If the positions of the two synchronized stations are known, then the position of the receiver
Receiver (radio)
A radio receiver converts signals from a radio antenna to a usable form. It uses electronic filters to separate a wanted radio frequency signal from all other signals, the electronic amplifier increases the level suitable for further processing, and finally recovers the desired information through...

 can be determined as being somewhere on a particular hyperbolic curve where the time difference between the received signals is constant. In ideal conditions, this is proportionally equivalent to the difference of the distances
Great-circle distance
The great-circle distance or orthodromic distance is the shortest distance between any two points on the surface of a sphere measured along a path on the surface of the sphere . Because spherical geometry is rather different from ordinary Euclidean geometry, the equations for distance take on a...

 from the receiver to each of the two stations.

So a LORAN receiver which only receives two LORAN stations cannot fully fix
Fix (position)
In position fixing navigation, a position fix or simply a fix is a position derived from measuring external reference points.The term is generally used with manual or visual techniques such as the use of intersecting visual or radio position lines rather than the use of more automated and accurate...

 its position - it only narrows it down to being somewhere on a curved line. Therefore the receiver must receive and calculate the time difference between a second pair of stations. This allows to be calculated a second hyperbolic line on which the receiver is located. Where these two lines cross is the location of the receiver.

In practice, one of the stations in the second pair also may be — and frequently is — in the first pair. This means signals must be received from at least three LORAN transmitters to pinpoint the receiver's location. By determining the intersection of the two hyperbolic curve
Curve
In mathematics, a curve is, generally speaking, an object similar to a line but which is not required to be straight...

s identified by this method, a geographic fix
Fix (position)
In position fixing navigation, a position fix or simply a fix is a position derived from measuring external reference points.The term is generally used with manual or visual techniques such as the use of intersecting visual or radio position lines rather than the use of more automated and accurate...

  can be determined.

LORAN method

In the case of LORAN, one station remains constant in each application of the principle, the master, being paired up separately with two other slave, or secondary, stations. Given two secondary stations, the time difference (TD) between the master and first secondary identifies one curve, and the time difference between the master and second secondary identifies another curve, the intersections of which will determine a geographic point in relation to the position of the three stations. These curves are referred to as TD lines.

In practice, LORAN is implemented in integrated regional arrays
Phased array
In wave theory, a phased array is an array of antennas in which the relative phases of the respective signals feeding the antennas are varied in such a way that the effective radiation pattern of the array is reinforced in a desired direction and suppressed in undesired directions.An antenna array...

, or chains, consisting of one master station and at least two (but often more) secondary (or slave) stations, with a uniform group repetition interval (GRI) defined in microsecond
Microsecond
A microsecond is an SI unit of time equal to one millionth of a second. Its symbol is µs.A microsecond is equal to 1000 nanoseconds or 1/1000 millisecond...

s. The master station transmits a series of pulses, then pauses for that amount of time before transmitting the next set of pulses.

The secondary stations receive this pulse signal from the master, then wait a preset amount of millisecond
Millisecond
A millisecond is a thousandth of a second.10 milliseconds are called a centisecond....

s, known as the secondary coding delay
Propagation delay
Propagation delay is a technical term that can have a different meaning depending on the context. It can relate to networking, electronics or physics...

, to transmit a response signal. In a given chain, each secondary's coding delay is different, allowing for separate identification of each secondary's signal. (In practice, however, modern LORAN receivers do not rely on this for secondary identification.)

LORAN chains (GRIs)

Every LORAN chain in the world uses a unique Group Repetition Interval, the number of which, when multiplied by ten, gives how many microseconds pass between pulses from a given station in the chain. (In practice, the delays in many, but not all, chains are multiples of 100 microseconds.) LORAN chains are often referred to by this designation (e.g., GRI 9960, the designation for the LORAN chain serving the Northeast United States
United States
The United States of America is a federal constitutional republic comprising fifty states and a federal district...

).

Due to the nature of hyperbolic curves, a particular combination of a master and two slave stations can possibly result in a "grid" where the grid lines intersect at shallow angles. For ideal positional accuracy, it is desirable to operate on a navigational grid where the grid lines are closer to right angles (orthogonal) to each other. As the receiver travels through a chain, a certain selection of secondaries whose TD lines initially formed a near-orthogonal grid can become a grid that is significantly skewed. As a result, the selection of one or both secondaries should be changed so that the TD lines of the new combination are closer to right angles. To allow this, nearly all chains provide at least three, and as many as five, secondaries.

LORAN charts

Where available, common marine nautical charts include visible representations of TD lines at regular intervals over water areas. The TD lines representing a given master-slave pairing are printed with distinct colors, and note the specific time difference indicated by each line. On a nautical chart the denotation for each Line of Position from a receiver, relative to axis and color, can be found at the bottom of the chart. The color on official charts for stations and the timed-lines of position follow no specific conformance for the purpose of the IHO - International Hydro-graphic Office. However, local chart producers may color these in a specific conformance to their standard. Always consult the chart notes, administrations Chart1 reference, and information given on the chart for the most accurate information regarding surveys, datum, and reliability.

There are three major factors when considering signal delay and propagation
Radio propagation
Radio propagation is the behavior of radio waves when they are transmitted, or propagated from one point on the Earth to another, or into various parts of the atmosphere...

 in relation to LORAN-C.

Primary Phase Factor (PF) : This allows for the fact that the speed of the propagated signal in the atmosphere is slightly lower than in a vacuum.

Secondary Phase Factor (SF) : This allows for the fact that the speed of propagation of the signal is slowed when traveling over the seawater because of the lower conductivity of seawater compared to land.

Additional Secondary Factors (ASF) : Because LORAN-C transmitters are mainly land based, the signal will travel partly over land and partly over seawater. ASF may be treated as land and water segments, each with a uniform conductivity depending on whether the path is over land or water.

For the purpose of C.H.S. Canadian Hydrographic Service charts the Additional Safety Factors are included in all transmissions for hyperbolic lines. Consult the chart notes or chart productions authority to determine if the ASF corrections have been made to the affective chart. For charts which have not been corrected for ASF, there is an ability to obtain correction factors. Please familiarize yourself with these items, before navigating with LORAN-C.

Also, due to interference and propagation issues suffered from land features and artificial structures such as tall buildings, the accuracy of the LORAN signal is degraded at its low frequency, considerably in inland areas. (See Limitations.) As a result, nautical charts will not print any TD lines in those areas, to prevent reliance on LORAN-C for navigation due to range, and angle of intersect of the Lines of Position.

On existing Lines of Position (LOP) on nautical charts, LORAN-C lines that are drawn can be solid, and then dashed in their appearance. According to International Hydrographic Offices Chart 1 there are various meanings for the dashing of a line. This dashed line should not be confused with other symbols such as an LOP from an adjoining chain, or a Half-lane LOP. Always consult the chart producers Chart 1 for the most accurate information on chart symbols.

Traditional LORAN receivers generally display the time difference between each pairing of the master and one of the two selected secondary stations. These numbers can then be found in relation to those of the TD lines printed on the chart. Modern LORAN receivers display latitude and longitude instead of time differences, and with the advent of time difference comparison and electronics provide improved accuracy and better position fixing. The expression of an ordinate in Degrees Minutes Seconds or Decimal will also allow the observer to plot on a nautical chart much easier. The type of ordinate and its survey delivered by the LORAN-C system must be understood for the comparison of it into a computer based charting system, or for use on a nautical chart. The survey of a specific chartis also of a huge concern with respect to the accuracy of position fixing. Most charts with respect to GPS / LORAN use the WGS84 survey. A charts survey (WGS84 / NAD) will be indicated on the chart notes and potentially at the bottom of the chart and should be consulted before use. Most modern GPS receivers also have the ability to change survey data from WGS84 to other surveys, allowing the position fixing on a chart of a different survey to still take place. Always use caution when receiving positional data from any electronic source.

Modern systems will include the LORAN-C in the decision making process of position fixing should the GPS or DGPS system fail, or default into Dead Reckoning. A good navigator will understand the order in which his or her system will default, and what systems are currently being sourced for navigational purposes.

Timing and synchronization

Each LORAN station is equipped with a suite of specialized equipment to generate the precisely timed signals used to modulate / drive the transmitting equipment. Up to three commercial cesium atomic clocks are used to generate 5 MHz and pulse per second
Pulse per second
A pulse per second is an electrical signal that very accurately repeats once per second . PPS signals are output by various types of precision clocks, including atomic clocks, radio clocks and some models of GPS receivers...

 (or 1 Hz) signals that are used by timing equipment to generate the various GRI-dependent drive signals for the transmitting equipment.

Each U.S.-operated LORAN station is synchronized to within ±100 ns of UTC.

Transmitters and antennas

LORAN-C transmitters operate at peak powers of 100 kilowatts to four megawatts, comparable to longwave
Longwave
In radio, longwave refers to parts of radio spectrum with relatively long wavelengths. The term is a historic one dating from the early 20th century, when the radio spectrum was considered to consist of long, medium and short wavelengths...

 broadcasting stations. Most LORAN-C transmitters use mast radiators insulated from ground with heights between 190 and 220 metres. The masts are inductively lengthened and fed by a loading coil
Loading coil
In electronics, a loading coil or load coil is a coil that does not provide coupling to any other circuit, but is inserted in a circuit to increase its inductance. The need was discovered by Oliver Heaviside in studying the disappointing slow speed of the Transatlantic telegraph cable...

 (see: electrical lengthening
Electrical lengthening
Electrical lengthening is the modification of an aerial which is shorter than a whole-number multiple of a quarter of the radiated wavelength, by means of a suitable electronic device, without changing the physical length of the aerial, in such a way that it corresponds electrically to the next...

). A well known-example of a station using such an antenna is LORAN-C transmitter Rantum
LORAN-C transmitter Rantum
The LORAN-C transmitter Rantum is a transmission facility for LORAN-C on the German island Sylt near the village Rantum at 54°48'30″N, 8°17'37″W. It was established in the 1960s, initially using a guyed steel framework mast with a triangular cross section, approximately 190 metres tall...

.

Free-standing tower radiators
Mast radiator
A mast radiator is a radio mast or tower in which the whole structure itself functions as an antenna. This design is commonly used for transmitting antennas operating at low frequencies, in the VLF, LF and MF ranges, in particular those used for AM broadcasting. The metal mast is electrically...

 in this height range are also used. LORAN-C transmitter Carolina Beach
LORAN-C transmitter Carolina Beach
LORAN-C transmitter Carolina Beach is the Zulu secondary station of the U.S. Southeast chain with a transmission power of 800 kW....

 uses a free-standing antenna tower.

Some LORAN-C transmitters with output powers of 1000 kW and higher used supertall mast radiators of around 412 metres in height (see below).

Other high power LORAN-C stations, like LORAN-C transmitter George
LORAN-C transmitter George
LORAN-C transmitter George serves the GRI 5990 and GRI 9940 chains. Transmission power is 1600 kW. It is located at George, Washington, USA at 47°3'48.096" N, 119°44'38.976" W .It went into service in September 1976...

, used four T-antennas mounted on four guyed masts arranged in a square.

All LORAN-C antennas radiate an omnidirectional pattern. Unlike longwave broadcasting stations, LORAN-C stations cannot use backup antennas. The slightly different physical location of a backup antenna would produce Lines of Position different from those of the primary antenna.

Limitations

LORAN suffers from electronic effects of weather and the ionospheric effects of sunrise and sunset. The most accurate signal is the groundwave that follows the Earth's surface, ideally over seawater. At night the indirect skywave
Skywave
Skywave is the propagation of electromagnetic waves bent back to the Earth's surface by the ionosphere. As a result of skywave propagation, a broadcast signal from a distant AM broadcasting station at night, or from a shortwave radio station can sometimes be heard as clearly as local...

, bent back to the surface by the ionosphere
Ionosphere
The ionosphere is a part of the upper atmosphere, comprising portions of the mesosphere, thermosphere and exosphere, distinguished because it is ionized by solar radiation. It plays an important part in atmospheric electricity and forms the inner edge of the magnetosphere...

, is a problem as multiple signals may arrive via different paths (multipath interference
Multipath interference
Multipath interference is a phenomenon in the physics of waves whereby a wave from a source travels to a detector via two or more paths and, under the right condition, the two components of the wave interfere...

). The ionosphere's reaction to sunrise and sunset accounts for the particular disturbance during those periods. Magnetic storm
Magnetic storm
Magnetic storm can refer to:* A geomagnetic storm* Magnetic Storm , the title of a book of paintings by Roger Dean* Magnetic Storm , the title of an hourlong PBS NOVA documentary about Earth's changing magnetic fields...

s have serious effects as with any radio based system.

LORAN uses ground based transmitters that only cover certain regions. Coverage is quite good in North America, Europe, and the Pacific Rim.

The absolute accuracy of LORAN-C varies from 0.1–0.25 nmi (185.2–463 m). Repeatable accuracy is much greater, typically from 60–300 ft (18.3–91.4 m).

LORAN-A and other systems

LORAN-A was a less accurate system operating in the upper mediumwave frequency band prior to deployment of the more accurate LORAN-C system. For LORAN-A the transmission frequencies 1750 kHz, 1850 kHz, 1900 kHz and 1950 kHz were used, shared with the 1800–2000 kHz amateur 160-meter band. LORAN-A continued in operation partly due to the economy of the receivers and widespread use in civilian recreational and commercial navigation. LORAN-B was a phase comparison variation of LORAN-A while LORAN-D was a short-range tactical system designed for USAF
United States Air Force
The United States Air Force is the aerial warfare service branch of the United States Armed Forces and one of the American uniformed services. Initially part of the United States Army, the USAF was formed as a separate branch of the military on September 18, 1947 under the National Security Act of...

 bombers. The unofficial "LORAN-F" was a drone control system. None of these went much beyond the experimental stage. An external link to them is listed below.

LORAN-A was used in the Vietnam War
Vietnam War
The Vietnam War was a Cold War-era military conflict that occurred in Vietnam, Laos, and Cambodia from 1 November 1955 to the fall of Saigon on 30 April 1975. This war followed the First Indochina War and was fought between North Vietnam, supported by its communist allies, and the government of...

 for navigation by large United States aircraft (C-124, C-130, C-97, C-123, HU-16, etc.). A common airborne receiver of that era was the R-65/APN-9 which combined the receiver and cathode ray tube
Cathode ray tube
The cathode ray tube is a vacuum tube containing an electron gun and a fluorescent screen used to view images. It has a means to accelerate and deflect the electron beam onto the fluorescent screen to create the images. The image may represent electrical waveforms , pictures , radar targets and...

 (CRT) indicator into a single relatively lightweight unit replacing the two larger, separate receiver and indicator units which composed the predecessor APN-4 system. The APN-9 and APN-4 systems found wide post-World War II
World War II
World War II, or the Second World War , was a global conflict lasting from 1939 to 1945, involving most of the world's nations—including all of the great powers—eventually forming two opposing military alliances: the Allies and the Axis...

 use on fishing vessels in the U.S. They were cheap, accurate and plentiful. The main drawback for use on boats was their need for aircraft power, 115 VAC at 400 Hz
Hertz
The hertz is the SI unit of frequency defined as the number of cycles per second of a periodic phenomenon. One of its most common uses is the description of the sine wave, particularly those used in radio and audio applications....

. This was solved initially by the use of rotary converter
Rotary converter
A rotary converter is a type of electrical machine which acts as a mechanical rectifier or inverter. It was used to convert AC to DC or DC to AC power before the advent of chemical or solid state power rectification...

s, typically 28 VDC input and 115 VAC output at 400 Hz. The inverters were large, noisy and required significant power. In the 1960s, several firms such as Topaz and Linear Systems marketed solid state
Solid state (electronics)
Solid-state electronics are those circuits or devices built entirely from solid materials and in which the electrons, or other charge carriers, are confined entirely within the solid material...

 inverters specifically designed for these surplus LORAN-A sets. The availability of solid state inverters that used 12 VDC input opened up the surplus LORAN-A sets for use on much smaller vessels which typically did not have the 24-28 VDC systems found on larger vessels. The solid state inverters were very power efficient and widely replaced the more trouble prone rotary inverters.

LORAN-A saved many lives by allowing offshore boats in distress to give accurate position reports. It also guided many boats whose owners could not afford radar safely into fog bound harbors or around treacherous offshore reefs. The low price of surplus LORAN-A receivers (often under $150) meant that owners of many small fishing vessels could afford this equipment, thus greatly enhancing safety. Surplus LORAN-A equipment, which was common on commercial fishing boats, was rarely seen on yachts. The unrefined cosmetic appearance of the surplus equipment was probably a deciding factor.

Pan American World Airways
Pan American World Airways
Pan American World Airways, commonly known as Pan Am, was the principal and largest international air carrier in the United States from 1927 until its collapse on December 4, 1991...

 used APN 9s in early Boeing 707 operations. World War II surplus APN-9 looked out of place in the modern 707 cockpit, but was needed. There is an R65A APN-9 set displayed in the museum at San Francisco International Airport
San Francisco International Airport
San Francisco International Airport is a major international airport located south of downtown San Francisco, California, United States, near the cities of Millbrae and San Bruno in unincorporated San Mateo County. It is often referred to as SFO...

, painted gold. It was a retirement gift to an ex Pan Am captain.

An elusive final variant of the APN 9 set was the APN 9A. A USAF technical manual (with photographs and schematics) shows that it had the same case as the APN-9 but a radically different front panel and internal circuitry on the non-RF portions. The APN-9A had vacuum tube flipflop
Flip-flop (electronics)
In electronics, a flip-flop or latch is a circuit that has two stable states and can be used to store state information. The circuit can be made to change state by signals applied to one or more control inputs and will have one or two outputs. It is the basic storage element in sequential logic...

 digital divider circuits so that TDs (time delays) between the master and slave signal could be selected on front panel rotary decade switches. The older APN-9 set required the user to perform a visual count of crystal oscillator timing marker pips on the CRT and add them up to get a TD. The APN 9A did not make it into widespread military use, if it was used at all, but it did exist and represented a big advance in military LORAN-A receiver technology.

In the 1970s one US company, SRD Labs in Campbell, California
Campbell, California
Campbell is a city in Santa Clara County, California, a suburb of San Jose, and part of Silicon Valley, in the San Francisco Bay Area. As of the 2010 U.S. Census, Campbell's population is 39,349...

, made modern LORAN-A sets including one that was completely automatic with a digital TD readout on the CRT, and autotracking so that TDs were continuously updated. Other SRD models required the user to manually align the master and slave signals on the CRT and then a phase locked loop would keep them lined up and provide updated TD readouts thereafter. These SRD LORAN-A sets would track only one pair of stations, providing just one LOP (line of position). For a continuously updated position (two TDs giving intersecting LOPs) rather than just a single LOP, two sets were necessary.

LORAN-A was terminated in the United States on December 31, 1980 and the restrictions on amateur radio use of the 160-meter band were lifted.

Long after LORAN-A broadcasts were terminated, commercial fishermen still referred to old LORAN-A TDs, e.g., "I am on the 4100 [microsecond] line in 35 fathoms", referring to a position outside of Bodega Bay
Bodega Bay
Bodega Bay is a shallow, rocky inlet of the Pacific Ocean on the coast of northern California in the United States. It is approximately across and is located approximately northwest of San Francisco and west of Santa Rosa...

. Many LORAN-C sets incorporated LORAN A TD converters so that a LORAN-C set could be used to navigate to a LORAN-A TD defined line or position.

LORAN Data Channel (LDC)

LORAN Data Channel (LDC) is a project underway between the FAA
Federal Aviation Administration
The Federal Aviation Administration is the national aviation authority of the United States. An agency of the United States Department of Transportation, it has authority to regulate and oversee all aspects of civil aviation in the U.S...

 and USCG
United States Coast Guard
The United States Coast Guard is a branch of the United States Armed Forces and one of the seven U.S. uniformed services. The Coast Guard is a maritime, military, multi-mission service unique among the military branches for having a maritime law enforcement mission and a federal regulatory agency...

 to send low bit rate data using the LORAN system. Messages to be sent include station identification, absolute time, and position correction messages. In 2001, data similar to Wide Area Augmentation System
Wide Area Augmentation System
The Wide Area Augmentation System is an air navigation aid developed by the Federal Aviation Administration to augment the Global Positioning System , with the goal of improving its accuracy, integrity, and availability...

 (WAAS) GPS
Global Positioning System
The Global Positioning System is a space-based global navigation satellite system that provides location and time information in all weather, anywhere on or near the Earth, where there is an unobstructed line of sight to four or more GPS satellites...

 correction messages were sent as part of a test of the Alaskan LORAN chain. As of November 2005, test messages using LDC were being broadcast from several U.S. LORAN stations.

In recent years, LORAN-C has been used in Europe to send differential GPS and other messages, employing a similar method of transmission known as EUROFIX.

A system called SPS (Saudi Positioning System), similar to EUROFIX, is in use in Saudi Arabia. GPS differential corrections and GPS integrity information are added to the LORAN signal. A combined GPS/LORAN receiver is used, and if a GPS fix is not available it automatically switches over to LORAN.

The future of LORAN

As LORAN systems are government maintained and operated, their continued existence is subject to public policy. With the evolution of other electronic navigation systems, such as Global Navigation Satellite System
Global Navigation Satellite System
A satellite navigation or SAT NAV system is a system of satellites that provide autonomous geo-spatial positioning with global coverage. It allows small electronic receivers to determine their location to within a few metres using time signals transmitted along a line-of-sight by radio from...

s (GNSS), funding for existing systems is not always assured.

Critics, who have called for the elimination of the system, state that the LORAN system has too few users, lacks cost-effectiveness, and that GNSS signals are superior to LORAN. Supporters of continued and improved LORAN operation note that LORAN uses a strong signal, which is difficult to jam, and that LORAN is an independent, dissimilar, and complementary system to other forms of electronic navigation, which helps ensure availability of navigation signals.

On 26 February 2009, the U.S. Office of Management and Budget released the first blueprint for the Financial Year 2010 budget
2010 United States federal budget
The United States Federal Budget for Fiscal Year 2010, titled A New Era of Responsibility: Renewing America's Promise, is a spending request by President Barack Obama to fund government operations for October 2009–September 2010...

. This document identified the LORAN-C system as “outdated” and supported its termination at an estimated savings of $36 million in 2010 and $190 million over five years.

On 21 April 2009 the U.S. Senate Committee on Commerce, Science and Transportation and the Committee on Homeland Security and Governmental Affairs released inputs to the FY 2010 Concurrent Budget Resolution with backing for the continued support for the LORAN system, acknowledging the investment already made in infrastructure upgrades and recognizing the studies performed and multi-departmental conclusion that eLORAN is the best backup to GPS.

Senator Jay Rockefeller, Chairman of the Committee on Commerce, Science and Transportation, wrote that the committee recognized the priority in "Maintaining LORAN-C while transitioning to eLORAN" as means of enhancing the homeland security, marine safety and environmental protection missions of the Coast Guard.

Senator Collins, the ranking member on the Committee on Homeland Security and Governmental Affairs wrote that the President's budget overview proposal to terminate the LORAN-C system is inconsistent with the recent investments, recognized studies and the mission of the U.S. Coast Guard. The committee also recognizes the $160 million investment already made toward upgrading the LORAN-C system to support the full deployment of eLORAN.

Further, the Committees also recognize the many studies which evaluated GPS backup systems and concluded both the need to back up GPS and identified eLORAN as the best and most viable backup. "This proposal is inconsistent with the recently released (January 2009) Federal Radionavigation Plan (FRP), which was jointly prepared by DHS and the Departments of Defense (DOD) and Transportation (DOT). The FRP proposed the eLORAN program to serve as a Position, Navigation and Timing (PNT) backup to GPS (Global Positioning System)."

On 7 May 2009, President Barack Obama proposed cutting funding (approx. $35 million/year) for LORAN, citing its redundancy alongside GPS. In regard to the pending Congressional bill, H.R. 2892, it was subsequently announced that "[t]he Administration supports the Committee's aim to achieve an orderly termination through a phased decommissioning beginning in January 2010, and the requirement that certifications be provided to document that the LORAN-C termination will not impair maritime safety or the development of possible GPS backup capabilities or needs."

Also on 7 May 2009, the U.S. General Accounting Office (GAO), the investigative arm of Congress, released a report citing the very real potential for the GPS system to degrade or fail in light of program delays which have resulted in scheduled GPS satellite launches slipping by up to three years.

On 12 May 2009 the March 2007 Independent Assessment Team (IAT) report on LORAN was released to the public. In its report the ITA stated that it "unanimously recommends that the U.S. government complete the eLORAN upgrade and commit to eLORAN as the national backup to GPS for 20 years." The release of the report followed an extensive Freedom Of Information Act (FOIA) battle waged by industry representatives against the federal government. Originally completed 20 March 2007 and presented to the co-sponsoring Department of Transportation and Department of Homeland Security (DHS) Executive Committees, the report carefully considered existing navigation systems, including GPS. The unanimous recommendation for keeping the LORAN system and upgrading to eLORAN was based on the team's conclusion that LORAN is operational, deployed and sufficiently accurate to supplement GPS. The team also concluded that the cost to decommission the LORAN system would exceed the cost of deploying eLORAN, thus negating any stated savings as offered by the Obama administration and revealing the vulnerability of the U.S. to GPS disruption.

In November 2009, the U.S. Coast Guard announced that the LORAN-C stations under its control would be closed down for budgetary reasons after January 4, 2010 provided the Secretary of the Department of Homeland Security certified that LORAN is not needed as a backup for GPS.

On 7 January 2010, Homeland Security published a notice of the permanent discontinuation of LORAN-C operation. Effective 2000 UTC 8 February 2010, the United States Coast Guard terminated all operation and broadcast of LORAN-C signals in the USA. The U.S. Coast Guard transmission of the Russian American CHAKYA signal was terminated on 1 August 2010. The transmission of Canadian LORAN-C signals was terminated on 3 August 2010.

eLORAN

With the perceived vulnerability of GNSS systems, and their own propagation and reception limitations, renewed interest in LORAN applications and development has appeared. Enhanced LORAN, also known as eLORAN or E-LORAN, comprises an advancement in receiver design and transmission characteristics which increase the accuracy and usefulness of traditional LORAN. With reported accuracy as good as ± 8 meters, the system becomes competitive with unenhanced GPS. eLORAN also includes additional pulses which can transmit auxiliary data such as DGPS corrections. eLORAN receivers now use "all in view" reception, incorporating signals from all stations in range, not solely those from a single GRI, incorporating time signals and other data from up to 40 stations. These enhancements in LORAN make it adequate as a substitute for scenarios where GPS is unavailable or degraded.

United Kingdom eLORAN implementation

On 31 May 2007, the UK Department for Transport (DfT), via the General Lighthouse Authorities
General Lighthouse Authority
A General Lighthouse Authority is a dedicated Government Agency of a Country or Nation tasked with and responsible for the provision and maintenance of lighthouses, lightvessels, navigational aids and any other equipment or facilities which ensure the safety of mariners and sailors navigating the...

 (GLA), awarded a 15-year contract to provide a state-of-the-art enhanced LORAN (eLORAN) service to improve the safety of mariners in the UK and Western Europe. The service contract will operate in two phases, with development work and further focus for European agreement on eLORAN service provision from 2007 through 2010, and full operation of the eLORAN service from 2010 through 2022. The first eLORAN transmitter is situated at Anthorn radio station Cumbria, UK, and operated by Babcock Comms, which is part of the Babcock Group PLC.

List of LORAN-C transmitters

A list of LORAN-C transmitters. Stations with an antenna tower taller than 300 metres (984 feet) are shown in bold.
Station Country Chain Coordinates Remarks
Afif Saudi Arabia Saudi Arabia South (GRI 7030)
Saudi Arabia North (GRI 8830)
23°48′36.66"N 42°51′18.17"E 400 kW
Al Khamasin Saudi Arabia Saudi Arabia South (GRI 7030)
Saudi Arabia North (GRI 8830)
20°28′2.34"N 44°34′51.9"E
Al Muwassam Saudi Arabia Saudi Arabia South (GRI 7030)
Saudi Arabia North (GRI 8830)
16°25′56.87"N 42°48′6.21"E
Angissq
Angissq LORAN-C transmitter
Angissq LORAN-C transmitter was a LORAN-C transmitter at Nanortalik-Angissq, Greenland of GRI 7930, 59°59'18"N, 45°10'24" W . Angissq LORAN-C transmitter had a transmission power of 1000 kilowatts....

Greenland Shutdown on December 31, 1994 59°59′17.348"N 45°10′26.916"W used until July 27, 1964 a 411.48 metre tower
Anthorn  UK Lessay (GRI 6731) 54°54′41.949"N 3°16′42.587"W replacement for transmitter Rugby
Ash Shaykh Humayd Saudi Arabia Saudi Arabia South (GRI 7030)
Saudi Arabia North (GRI 8830)
28°9′15.87"N 34°45′41.36"E
Attu Island United States North Pacific (GRI 9990)
Russian-American (GRI 5980)
52°49′44"N 173°10′49.7"E demolished in August 2010
Balasore India Calcutta (GRI 5543) 21°29′11.02"N 86°55′9.66"E
Barrigada Guam shut down 13°27′50.16"N 144°49′33.4"E
Baudette United States North Central U.S. (GRI 8290)
Great Lakes (GRI 8970)
48°36′49.947"N 94°33′17.915"W
Berlevåg Norway Bø (GRI 7001) 70°50′43.07"N 29°12′16.04"E
Billamora India Bombay (GRI 6042) 20°45′42.036"N 73°02′14.482"E
Boise City United States Great Lakes (GRI 8970)
South Central U.S. (GRI 9610)
36°30′20.75"N 102°53′59.4"W
Bø, Vesterålen Norway Bø (GRI 7001)
Eiði (GRI 9007)
68°38′06.216"N 14°27′47.350"E
Cambridge Bay
Cambridge Bay LORAN Tower
Cambridge Bay LORAN Tower is a tall free-standing lattice tower at Cambridge Bay, Nunavut, Canada. It was built in 1947/48 for LORAN transmissions. Today the tower is used as a Non-directional beacon and is often called to the "CB" beacon after the morse code letters that it transmits on 245 kHz,...

 
Canada shut down 69°06′52.840"N 105°00′55.953"W free-standing lattice tower, used as NDB
Non-directional beacon
A non-directional beacon is a radio transmitter at a known location, used as an aviation or marine navigational aid. As the name implies, the signal transmitted does not include inherent directional information, in contrast to other navigational aids such as low frequency radio range, VHF...

Cape Race
Cape Race LORAN-C transmitter
The Cape Race LORAN-C transmitter is a LORAN-C transmitter at Cape Race, Newfoundland, Canada.The Cape Race LORAN-C transmitter was used as an antenna tower until February 2, 1993. It was a 411.48 m tall guyed mast, built in 1965...

Canada Canadian East Coast (GRI 5930)
Newfoundland East Coast (GRI 7270)
46°46′32.74"N 53°10′28.66"W used a 411.48 metre tall tower until February 2, 1993, uses now a 260.3 metre tall tower
Caribou, Maine United States Canadian East Coast (GRI 5930)
Northeast U.S. (GRI 9960)
46°48′27.305"N 67°55′37.159"W
Carolina Beach United States Southeast U.S. (GRI 7980)
Northeast US (GRI 9960)
34°03′46.208"N 77°54′46.100"W
Chongzuo China China South Sea (GRI 6780) 22°32′35.8"N 107°13′19"E
Comfort Cove Canada Newfoundland East Coast (GRI 7270) 49°19′53.65"N 54°51′43.2"W
Dana United States Great Lakes (GRI 8970)
Northeast US (GRI 9960)
39°51′7.64"N 87°29′10.71"W
Dhrangadhra India Bombay (GRI 6042) 23°0′16.2"N 71°31′37.64"E
Diamond Harbor India Calcutta (GRI 5543) 22°10′20.42"N 88°12′15.8"E
Eiði
LORAN-C transmitter Ejde
LORAN-C transmitter Ejde is the Master station of the Ejde LORAN-C Chain .It uses a transmission power of 400 kW.Ejde LORAN-C transmitter, situated near Eiði at...

 
Faroe Islands Eiði (GRI 9007) 62°17′59.69"N 7°4′25.59"W
Estartit
LORAN-C transmitter Estartit
Coast Guard LORAN-C Station Estartit was the Zulu secondary station of the Mediterrean Sea LORAN-C Chain .It used a transmission power of 165 kW.Estartit LORAN-C transmitter, was situated near Estartit at...

 
Spain Mediterranean Sea (GRI 7990)
(Shut down)
42°3′36.63"N 3°12′16.08"E
Fallon
LORAN-C transmitter Fallon
LORAN-C transmitter Fallon was the Master station of the U.S. West Coast LORAN-C Chain . It used a transmission power of 400 kW.The Fallon LORAN-C transmitter was situated near Fallon, Nevada at . Fallon LORAN-C transmitter used a tall mast radiator.The station was closed on February 8, 2010 as a...

 
United States U.S. West Coast (GRI 9940) 39°33′6.77"N 118°49′55.6"W
Fox Harbour Canada Canadian East Coast (GRI 5930)
Newfoundland East Coast (GRI 7270)
52°22′35.29"N 55°42′28.68"W
George United States Canadian West Coast (GRI 5990) 47°03′48.096"N 119°44′38.976"W
Gesashi
LORAN-C transmitter Gesashi
LORAN-C transmitter Gesashi is the Whiskey secondary station of the North West Pacific LORAN-C Chain and the X-Ray Secondary of the East Asia LORAN-C chain .It uses for both chains a transmission power of 1000 kW....

 
Japan North West Pacific (GRI 8930)
East Asia (GRI 9930)
26°36′25.09"N 128°8′56.94"E
Gillette
LORAN-C transmitter Gillette
The LORAN-C transmitter Gillette was a LORAN-C transmission facility near Gillette, Wyoming at . Its aerial, a guyed radio mast, is the tallest structure in Wyoming....

 
United States North Central U.S. (GRI 8290)
South Central U.S. (GRI 9610)
44°0′11.21"N 105°37′24"W
Grangeville
LORAN-C transmitter Grangeville
LORAN-C transmitter Grangeville was the Whiskey secondary station of the Southeast U.S. LORAN-C Chain .It used a transmission power of 800 kW.Grangeville LORAN-C transmitter, was situated at Grangeville, Louisiana at 30°43'33" N, 90°49'43" W,....

 
United States Southeast U.S. (GRI 7980)
South Central U.S. (GRI 9610)
30°43′33.24"N 90°49′43.01"W
Havre
LORAN-C transmitter Havre
LORAN-C transmitter Havre was the master station of the North-Central U.S. LORAN-C Chain .It used a transmission power of 400 kW. Havre LORAN-C transmitter was situated at Havre, Montana at 48°44'39" N, 109°58'54" W,. Havre LORAN-C transmitter used as an antenna a tall mast radiator.The station...

 
United States North Central U.S. (GRI 8290) 48°44′38.58"N 109°58′53.3"W
Hellissandur
Longwave radio mast Hellissandur
The Longwave radio mast Hellissandur is a 412 metre high guyed radio mast for longwave transmissions at Gufuskálar in the vicinity of Hellissandur on the peninsula Snæfellsnes of Iceland. This mast, which is the tallest structure in Western Europe, is insulated against ground and guyed in 5 levels...

Iceland shut down on December 31, 1994 64°54′14.793"N 23°54′47.837"W 411.48 metre tall tower, now used for longwave broadcasting of RÚV
RÚV
Ríkisútvarpið is Iceland's national public-service broadcasting organization.Operating from studios in the country's capital, Reykjavík, as well as regional centres around the country, the service broadcasts a variety of general programming to a wide audience across the whole country via radio...

 on 189 kHz
Helong
LORAN-C transmitter Helong
LORAN-C transmitter Helong is the Yankee secondary of the China North Sea LORAN-C Chain .It uses a transmission power of 1200 kW.LORAN-C transmitter Helong is situated near Helong at ....

 
China China North Sea (GRI 7430) 42°43′11"N 129°6′27.07"E
Hexian
LORAN-C transmitter Hexian
LORAN-C transmitter Hexian is the master station of the China South Sea LORAN-C Chain .It uses a transmission power of 1200 kW.LORAN-C transmitter Hexian is situated near Hexian at ....

 
China China South Sea (GRI 6780) 23°58′3.21"N 111°43′9.78"E
Iwo Jima
Iwo Jima LORAN-C transmitter
Iwo Jima LORAN-C transmitter was a LORAN-C transmitter at Iwo Jima, Japan of Grid 9970 at . Iwo Jima LORAN-C transmitter had a transmission power of 4000 kilowatts, which is more than the most powerful broadcasting stations....

Japan shut down in September 1993, dismantled 24°48′26.262"N 141°19′34.761"E used a 411.48 metre tall tower
Jan Mayen
LORAN-C transmitter Jan Mayen
The LORAN-C transmitter Jan Mayen is a LORAN-C transmission facility on the island of Jan Mayen at . The LORAN-C transmitter Jan Mayen uses as antenna a 190-metre high guyed mast....

 
Norway Bø (GRI 7001)
Ejde (GRI 9007)
70°54′51.478"N 8°43′56.525"W
Johnston Island
LORAN-C transmitter Johnston Island
LORAN-C transmitter Johnston Island was a LORAN-C transmitter on Johnston Atoll, in the mid-Pacific Ocean. It was in service until July 1, 1992 and used as antenna a 190.5 metre tall mast radiator and a transmission power of 275 kW....

 
United States shut-down 16°44′43.82"N 169°30′30.9"W
Jupiter
LORAN-C transmitter Jupiter
LORAN-C transmitter Jupiter is the Yankee secondary station of the Southeast U.S. LORAN-C Chain . It uses a transmission power of 165 kW.Jupiter LORAN-C transmitter, situated at Jupiter, Florida at 27°1'59" N, 80°6'53" W...

 
United States Southeast U.S. (GRI 7980) 27°1′58.49"N 80°6′52.83"W
Kargaburan
LORAN-C transmitter Kargaburan
LORAN-C transmitter Kargabarun is the Yankee secondary station of the Mediterrean Sea LORAN-C Chain .It use a transmission power of 165 kW.Kargabarun LORAN-C transmitter, situated at Kargabarun at 40°58'21" N, 27°52'2" E,....

 
Turkey Mediterranean Sea (GRI 7990)
(Shut down)
40°58′20.51"N 27°52′1.89"E
Kwang Ju South Korea East Asia (GRI 9930) 35°2′23.69"N 126°32′27.2"E
Lampedusa
LORAN-C transmitter Lampedusa
LORAN-C transmitter Lampedusa is the X-Ray secondary station of the Mediterranean Sea LORAN-C Chain .It uses a transmission power of 325 kW....

 
Italy Mediterranean Sea (GRI 7990)
(Shut down)
35°31′22.11"N 12°31′31.06"E
Las Cruces United States South Central U.S. (GRI 9610) 32°4′18.1"N 106°52′4.32"W
Lessay France Lessay (GRI 6731)
Sylt (GRI 7499)
49°8′55.27"N 1°30′17.03"W
Loop Head Ireland Lessay (GRI 6731)
Eiði (GRI 9007)
(Never built) 250 kW
Malone
LORAN-C transmitter Malone
LORAN-C transmitter Malone was the master station of the Southeast U.S. LORAN-C Chain and the Whiskey Secondary of the Great Lakes chain . It used a transmission power of 800 kW for both chains....

 
United States Southeast U.S. (GRI 7980)
Great Lakes (GRI 8970)
30°59′38.87"N 85°10′8.71"W
Middletown United States U.S. West Coast (GRI 9940) 38°46′57.12"N 122°29′43.9"W
Minamitorishima
Marcus Island LORAN-C transmitter
Marcus Island LORAN-C transmitter is a LORAN-C transmitter on Marcus Island , Japan at...

Japan North West Pacific (GRI 8930) 24°17′8.79"N 153°58′52.2"E used until 1985 a 411.48 metre tall tower
Nantucket
United States Coast Guard A/C Loran Transmitter Station, Nantucket
Nantucket LORAN-C transmitter was a LORAN-C transmitter at Siasconset, Massachusetts. It was built in 1963 with a 625 ft tall mast radiator. It operated in conjunction with the LORAN-A station on Nantucket from 1963-1981...

 
United States Canadian East Coast (GRI 5930)
Northeast U.S. (GRI 9960)
41°15′12.42"N 69°58′38.73"W
Narrow Cape United States Gulf of Alaska (GRI 7960)
North Pacific (GRI 9990)
57°26′20.5"N 152°22′10.2"W
Niijima Japan North West Pacific (GRI 8930)
East Asia (GRI 9930)
34°24′12.06"N 139°16′19.4"E
Patpur India Calcutta (GRI 5543) 20°26′50.627"N 85°49′38.679"E
Pohang South Korea North West Pacific (GRI 8930)
East Asia (GRI 9930)
36°11′5.33"N 129°20′27.4"E
Port Clarence
LORAN-C transmitter Port Clarence
The LORAN-C transmitter Port Clarence was a transmission facility for LORAN-C situated at Port Clarence, Alaska at . It used as aerial a 411.48m high guyed mast, which was built in 1961 and which was the tallest construction of Alaska until its demolition with explosives on April 28, 2010.-External...

United States Gulf of Alaska (GRI 7960)
North Pacific (GRI 9990)
65°14′40.372"N 166°53′11.996"W uses a 411.48 metre tall tower Demolished April 28, 2010
Port Hardy Canada Canadian West Coast (GRI 5990) 50°36′29.830"N 127°21′28.489"W
Rantum
LORAN-C transmitter Rantum
The LORAN-C transmitter Rantum is a transmission facility for LORAN-C on the German island Sylt near the village Rantum at 54°48'30″N, 8°17'37″W. It was established in the 1960s, initially using a guyed steel framework mast with a triangular cross section, approximately 190 metres tall...

 
Germany Lessay (GRI 6731)
Sylt (GRI 7499)
54°48′29.94"N 8°17′36.9"E
Raymondville United States Southeast U.S. (GRI 7980)
South Central U.S. (GRI 9610)
26°31′55.17"N 97°49′59.52"W
Raoping China China South Sea (GRI 6780)
China East Sea (GRI 8390)
23°43′26.02"N 116°53′44.7"E
Rongcheng China China North Sea (GRI 7430)
China East Sea (GRI 8390)
37°03′51.765"N 122°19′25.954"E
Rugby  UK Experimental (GRI 6731)
Shut down at the end of July 2007
52°21′57.893"N 1°11′27.397"W
Saint Paul
LORAN-C transmitter Saint Paul
LORAN-C transmitter Saint Paul is the master station of the North Pacific LORAN-C Chain .It uses a transmission power of 325 kW.Saint Paul LORAN-C transmitter, situated at Saint Paul, Alaska at...

 
United States North Pacific (GRI 9990) 57°9′12.35"N 170°15′6.06"W
Salwa
LORAN-C transmitter Salwa
LORAN-C transmitter Salwa is the Whiskey secondary of the Saudi Arabia South LORAN-C Chain and the Whiskey secondary of the Saudi Arabia North LORAN-C Chain .It uses for both chains a transmission power of 1000 kW....

 
Saudi Arabia Saudi Arabia South (GRI 7030)
Saudi Arabia North (GRI 8830)
24°50′1.46"N 50°34′12.54"E
Searchlight
LORAN-C transmitter Searchlight
LORAN-C transmitter Searchlight was the Yankee secondary of the U.S. West Coast LORAN-C Chain and the Whiskey secondary of the South Central U.S. Chain . The station, established in 1976, consisted of four transmission towers. It transmitted 540 kW from south of Searchlight, Nevada...

 
United States South Central U.S. (GRI 9610)
U.S. West Coast (GRI 9940)
35°19′18.305"N 114°48′16.881"W
Sellia Marina Italy Mediterranean Sea (GRI 7990); shut down 38°52′20.72"N 16°43′6.27"E
Seneca
LORAN-C transmitter Seneca
The LORAN-C transmitter Seneca is the master station of the Northeast US LORAN-C Chain and the X-Ray secondarystation of the Great Lakes Chain . It is located within the Seneca Army Depot in Romulus, New York, South of Geneva, New York. It uses a 1000 Kilowatt; 700 foot guyed mast that was...

 
United States Great Lakes (GRI 8970)
Northeast U.S. (GRI 9960)
42°42′50.716"N 76°49′33.308"W
Shoal Cove United States Canadian West Coast (GRI 5990)
Gulf of Alaska (GRI 7960)
55°26′20.940"N 131°15′19.094"W
Soustons France Lessay (GRI 6731) 43°44′23.21"N 1°22′49.63"W
Tok United States Gulf of Alaska (GRI 7960) 63°19′42.884"N 142°48′31.346"W
Tokachibuto Japan Eastern Russia Chayka (GRI 7950)
North West Pacific (GRI 8930)
42°44′37.2"N 143°43′10.5"E
Upolo Point United States Shut down 20°14′51.12"N 155°53′4.34"W
Værlandet Norway Sylt (GRI 7499)
Ejde (GRI 9007)
61°17′49.49"N 4°41′47.05"E
Veraval India Bombay (GRI 6042) 20°57′09.316"N 70°20′11.730"E
Williams Lake Canada Canadian West Coast (GRI 5990)
North Central U.S. (GRI 8290)
51°57′58.78"N 122°22′1.55"W
Xuancheng China China North Sea (GRI 7430)
China East Sea (GRI 8390)
31°4′8.3"N 118°53′8.78"E
Yap Micronesia shut down in 1987, dismantled 9°32′44.76"N 138°9′53.48"E used a 304.8 metre tall tower

See also

  • CHAYKA
    CHAYKA
    Chayka is a Russian terrestrial radio navigation system, similar to LORAN-C. It is also run on 100 kHz and is described like LORAN-C by its GRI.-Chayka-Chains:There are 5 Chayka-chains in use:...

    , the Russian counterpart of LORAN
  • Alpha
    Alpha (radio navigation)
    Alpha is a Russian system for long range radio navigation. RSDN in Russian stands for , i.e., radio-technical long-distance navigation system....

    , the Russian counterpart of the Omega Navigation System, still in use as of 2006.
  • OMEGA
    OMEGA Navigation System
    OMEGA was the first truly global radio navigation system for aircraft, operated by the United States in cooperation with six partner nations.-History:OMEGA was originally developed by the United States Navy for military aviation users...

    , the Western counterpart of the Alpha Navigation System, no longer in use.
  • Decca Navigator System
    Decca Navigator System
    The Decca Navigator System was a low frequency hyperbolic navigation system that was first deployed during World War II when the Allied forces needed a system which could be used to achieve accurate landings...

    , a British system that used phase
    Phase (waves)
    Phase in waves is the fraction of a wave cycle which has elapsed relative to an arbitrary point.-Formula:The phase of an oscillation or wave refers to a sinusoidal function such as the following:...

     difference instead of time difference.
  • SHORAN
    SHORAN
    SHORAN is an acronym for SHOrt RAnge Navigation, a type of electronic navigation and bombing system with a precision radar beacon used in the B-26 and B-29 bomber aircraft during the Korean War.-Origin:...

  • Oboe (navigation)
    Oboe (navigation)
    Oboe was a British aerial blind bombing targeting system in World War II, based on radio transponder technology. Oboe accurately measured the distance to an aircraft, and gave the pilot guidance on whether or not they were flying along a pre-selected circular route. The route was only 35 yards...

  • G-H (navigation)
    G-H (navigation)
    Gee-H, or sometimes G-H, was a radio navigation system developed by Britain during World War II to aid RAF Bomber Command. Its official name was AMES Type 100...

  • GEE (navigation)
    GEE (navigation)
    Gee was the code name given to a radio navigation system used by the Royal Air Force during World War II.Different sources record the name as GEE or Gee. The naming supposedly comes from "Grid", so the lower case form is more correct, and is the form used in Drippy's publications. See Drippy 1946....

  • GPS
  • Local positioning system

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