LORAN
LORAN ( English Lo ng Ra length N AVIGATION ) is a radio navigation system , which mainly used for navigation in the maritime and in the aviation is used.
technology
The current version of LORAN-C is based on broadcast stations to chains ( chains are) grouped. A chain consists of a main transmitter and two to five secondary transmitters located a few hundred kilometers away. The stations send pulse groups according to a fixed scheme. From the time difference with which the signals arrive at the receiver, he can calculate hyperbolic base lines and from their intersection his position. Therefore it is a hyperbola navigation . In order to achieve a clear identification of the main and secondary transmitters in a chain and to avoid mutual interference, the individual transmitters do not transmit at the same time, but offset from one another by a defined delay time. The group repetition interval (GRI) and the secondary transmitter delay times ( emission delay ) are dimensioned in such a way that there is no overlap, even at distant receiver locations, i.e. long signal propagation times. The LORAN-C signal is broadcast at a frequency of 100 kHz, with a range of over 1000 km.
Modern receivers offer a repeat accuracy of up to ten meters with good reception . Since the speed of propagation of the signal mainly depends on the nature of the earth's surface (water / land, summer / winter), these factors must be taken into account in order to achieve good absolute position accuracy. Without these so-called ASF corrections ( additional secondary factors ), the absolute accuracy is a few hundred meters. The geometry, i.e. H. the position of the receiver in relation to the transmitter stations has a significant influence on the accuracy. Outside of the range between the received Loran-C transmitters, the accuracy drops very significantly and can be in the range of a few kilometers.
history
The LORAN-C system was preceded by a project initiated by Alfred Lee Loomis in 1940 at the Radiation Laboratory of the Massachusetts Institute of Technology , LORAN-A, the development of which was initiated by the US Navy during World War II , and its extension LORAN-B, the but was not used beyond the experimental stage. LORAN-C achieves a much higher accuracy than LORAN-A, is very insensitive to weather influences and can be used around the clock with constant precision. The US LORAN-C system was operational in 1957 and has been operated by the US Coast Guard since 1958 . In 1974 the decision was made to phase out LORAN-A and to make LORAN-C the primary navigation system for the coastal waters of the USA and Alaska .
In May 2009, the USA announced that it would shut down its Loran-C network for cost reasons, as satellite-based navigation is now state of the art. The last US Coast Guard station, Caribou in Maine , ceased operations on September 1, 2010. The further development of the eLORAN service is also no longer supported by the USA.
NELS
In Europe, the Northwest European LORAN-C System (NELS) came into being when the US military stopped operating the stations. On August 6, 1992, the four European countries signed a corresponding contract with LORAN-C transmitters (France (2 transmitters), Germany ( Rantum ), Ireland, the Netherlands and Norway ( Bø and Jan Mayen )). In Norway, the stations Værlandet and Berlevåg were also created. There are also plans to build a new transmitter station in Loophead , Ireland. The stations are administered by the respective country and are no longer under military control. On December 31, 1994, the stations that were operated by the US Navy in Europe were handed over to the respective host country and mostly renewed technically by them. LORAN-C is used by the European NELS to broadcast differential corrections to the GPS signal (see differential GPS ). This technology is called Eurofix .
Channel
Broadcasting stations are not only located in the USA, but are operated worldwide. LORAN-C can be used in the North Pacific (including the Bering Sea ), the North Atlantic , the Mediterranean , the North and Baltic Seas , the Red Sea and the Persian Gulf . An equivalent system called CHAYKA was developed in the Soviet Union , but it was mainly set up inland .
The only LORAN-C transmitter in Germany was the LORAN-C transmitter Rantum on the island of Sylt . Its broadcasting was stopped on December 31, 2015.
Saudi Arabia has been building the Saudi Positioning System (SPS) since 2005 , similar to Eurofix, a combination of LORAN-C, GPS and DGPS .
LORAN-C transmitters have transmission powers between 100 kW and 4000 kW. The transmission antennas used are mostly self-radiating transmission masts insulated from the ground and with a roof capacity of around 190 meters to 220 meters in height, but transmission masts over 400 m in height have also been erected for some very powerful stations.
The Minami-Torishima transmitter is a transmission facility of the Grid 9970 chain on Minamitori-shima. The transmitter has a transmission power of 4000 kW, making it one of the most powerful transmitters in the world. He uses a 213 m (up to 1985: 411.48 m) high, self-radiating transmission mast as a transmitting antenna.
The transmitter Iwo was a transmission means of the chain Grid 9970 on Iwo at 24 ° 48 '6 " N , 141 ° 19' 30" O . The transmitter had a transmission power of 4000 kW, making it one of the most powerful transmitters in the world. In 1965, the station's 411.48 m high transmitter mast overturned during maintenance work and also destroyed the transmitter building and all of its technical equipment. The system was rebuilt, with the new transmitter also receiving a 411.48 m high transmission mast. In September 1993 the system was shut down and the antenna mast dismantled.
The transmitter Cape Race is a transmission device of the chain grid 9930 at Cape Race at 46 ° 46 '30 " N , 53 ° 10' 30" W . The transmitter has a transmission power of 1800 kW. He used a 411.48 m high, self-radiating transmission mast as the transmitting antenna. On February 2, 1993 this transmission tower collapsed. It was replaced by a 260.3 m high, self-radiating transmission mast.
List of LORAN-C transmission chains
| GRI | Chain | system | comment |
|---|---|---|---|
| 4970 | Northwestern Russia | CHAYKA | Out of service |
| 4990 | Central Pacific | LORAN | Out of service |
| 5543 | Calcutta | LORAN | |
| 5930 | Canada east coast | LORAN | |
| 5960 | Northern Russia | CHAYKA | Out of service |
| 5980 | Russia America | CHAYKA | |
| 5990 | Canada west coast | LORAN | |
| 6042 | Bombay | LORAN | |
| 6731 | Lessay (Western Europe) | LORAN | |
| 6780 | South China Sea | LORAN | |
| 6930 | China | LORAN | Out of service |
| 7001 | Bø (Northern Europe) | LORAN | |
| 7030 | Saudi Arabia South | LORAN | |
| 7170 | Saudi Arabia South | LORAN | Out of service |
| 7270 | Newfoundland east coast | LORAN | |
| 7430 | China Yellow Sea | LORAN | |
| 7499 | Sylt (North / Baltic Sea) | LORAN | Out of service |
| 7930 | Labrador Sea | LORAN | Out of service |
| 7950 | Eastern Russia | CHAYKA | |
| 7960 | Gulf of Alaska | LORAN | |
| 7970 | Norwegian sea | LORAN | Out of service |
| 7980 | Southeast USA | LORAN | |
| 7990 | Mediterranean Sea | LORAN | Out of service |
| 8000 | Western Russia | CHAYKA | |
| 8290 | North / Central USA | LORAN | |
| 8390 | East China Sea | LORAN | |
| 8830 | Saudi Arabia North | LORAN | |
| 8930 | Northwest Pacific | LORAN | |
| 8970 | Big lakes | LORAN | |
| 8990 | Saudi Arabia South | LORAN | Out of service |
| 9007 | Ejde | LORAN | |
| 9610 | South / Central USA | LORAN | |
| 9930 | East asia | LORAN | |
| 9940 | West coast USA | LORAN | |
| 9960 | Northeast USA | LORAN | |
| 9970 | Northwest Pacific | LORAN | Out of service |
| 9980 | Iceland | LORAN | Out of service |
| 9990 | North Pacific | LORAN |
List of LORAN-C broadcasting stations
The geographical coordinates of the transmitting stations are contained in the table List of LORAN-C transmitters on the English language Wikipedia.
| station | country | Chain | Remarks |
|---|---|---|---|
| Afif | Saudi Arabia | Saudi Arabia South (GRI 7030) / Saudi Arabia North (GRI 8830) | |
| Al Khamasin | Saudi Arabia | Saudi Arabia South (GRI 7030) / Saudi Arabia North (GRI 8830) | |
| Al Muwassam | Saudi Arabia | Saudi Arabia South (GRI 7030) / Saudi Arabia North (GRI 8830) | |
| Angisoq | Greenland | shut down on December 31, 1994 | used a 411.48 meter high antenna tower until July 27, 1964 |
| Anthorn | UK | Lessay (GRI 6731) | Replacement for Rugby transmitter, also used for MSF (time signal transmitter) and GBZ |
| Ash Shayk | Saudi Arabia | Saudi Arabia South (GRI 7030) / Saudi Arabia North (GRI 8830) | |
| Attu | Alaska | North Pacific (GRI 9990) / Russian-American (GRI 5980) | |
| Balasore | India | Calcutta (GRI 5543) | |
| Barrigada | Guam | shut down | |
| Baudette , Minnesota | United States | North Central USA (GRI 8290) / Great Lakes (GRI 8970) | |
| Berlevåg | Norway | Bø (GRI 7001) | |
| Billamora | India | Bombay (GRI 6042) | |
| Boise City , Oklahoma | United States | Great Lakes (GRI 8970) / South Central USA (GRI 9610) | |
| Cambridge Bay | Canada | Italy | Free-standing steel lattice tower , used today as an NDB |
| Cape Race | Canada | Canadian East Coast (GRI 5930) / Newfoundland East Coast (GRI 7270) | used a 411.48 meter high antenna tower until February 2, 1993 |
| Carolina Beach , North Carolina | United States | Northeast US (GRI 9960) / Southeast USA (GRI 7980) | |
| Chongzuo | China | China South Sea (GRI 6780) | |
| Comfort Cove | Canada | Newfoundland East Coast (GRI 7270) | |
| Dhrangadhra | India | Bombay (GRI 6042) | |
| Diamond Harbor | India | Calcutta (GRI 5543) | |
| Ejde | Faroe Islands | Ejde (GRI 9007) | |
| Estartit | Spain | Mediterranean Sea (GRI 7990); Out of service | |
| Fallon , Montana | United States | USA West Coast (GRI 9940) | |
| Fox Harbor | Canada | Newfoundland East Coast (GRI 7270) / Canadian East Coast (GRI 5930) | |
| George | Canada | Canadian West Coast (GRI 5990) / USA West Coast (GRI 9940) | |
| Gesashi | Japan | East Asia (GRI 9930) / North West Pacific (GRI 8930) | |
| Gillette , Wyoming | United States | South Central USA (GRI 9610) / North Central USA (GRI 8290) | |
| Grangeville , Idaho | United States | South Central USA (GRI 9610) / Southeast USA (GRI 7980) | |
| Havre | Canada | North Central USA (GRI 8290) | |
| Hellissandur | Iceland | shut down on December 31, 1994 | 411.48 meter high antenna tower , today used to broadcast a radio program for the Icelandic radio ( Ríkisútvarpið ) on the frequency 189 kHz |
| Helong | China | China North Sea (GRI 7430) | |
| Hexian | China | China South Sea (GRI 6780) | |
| Jan Mayen | Norway | Bø (GRI 7001) | The transmitter is in Olonkinbyen |
| Johnston Island | United States | Italy | |
| Iwo Jima | Japan | shut down in September 1993, dismantled | used a 411.48 meter high antenna tower |
| Jupiter , Florida | United States | Southeast USA (GRI 7980) | |
| Kargaburan | Turkey | Mediterranean Sea (GRI 7990); Out of service | |
| Kwang Ju | South Korea | East Asia (GRI 9930) | |
| Lampedusa | Italy | Mediterranean Sea (GRI 7990); Out of service | |
| Las Cruces , New Mexico | United States | South Central USA (GRI 9610) | |
| Lessay | France | Lessay (GRI 6731) / Sylt (GRI 7499) | |
| Malone , Florida | United States | Great Lakes (GRI 8970) / Southeast USA (GRI 7980) | |
| Minamitorishima | Japan | North West Pacific (GRI 8930) | used a 411.48 meter high antenna tower until 1985 |
| Nantucket | Canada | Canadian East Coast (GRI 5930) / Northeast USA (GRI 9960) | |
| Narrow Cape | Alaska | North Pacific (GRI 9990) / Gulf of Alaska (GRI 7960) | |
| Niijima | Japan | North West Pacific (GRI 8930) / East Asia (GRI 9930) | |
| Patpur | India | Calcutta (GRI 5543) | |
| Pohang | South Korea | North West Pacific (GRI 8930) / East Asia (GRI 9930) | |
| Port Clarence | Alaska | Gulf of Alaska (GRI 7960) / North Pacific (GRI 9990) | uses a 411.48 meter high antenna tower |
| Port Hardy | Canada | Canadian West Coast (GRI 5990) | |
| Rantum | Germany | Sylt (GRI 7499) / Lessay (GRI 6731) | uses a 193 meter high steel lattice mast, cessation of operations on December 31, 2015, 11:00 a.m. UTC |
| Raymondville , Texas | United States | South Central USA (GRI 9610) / Southeast USA (GRI 7980) | |
| Raoping | China | China South Sea (GRI 6780) / China East Sea (GRI 8930) | |
| Rongcheng | China | China North Sea (GRI 7430) / China East Sea (GRI 8930) | |
| rugby | UK | Lessay (GRI 6731); experimental: out of service since July 2007 | |
| Saint Paul | Alaska | North Pacific (GRI 9990) | |
| Salwa | Saudi Arabia | Saudi Arabia North (GRI 8830) / Saudi Arabia South (GRI 7030) | |
| Searchlight , Nevada | United States | USA West Coast (GRI 9940) / South Central USA (GRI 9610) | |
| Sellia Marina | Italy | Mediterranean Sea (GRI 7990); Out of service | |
| Seneca , New York | United States | Great Lakes (GRI 8970) / Northeast USA (GRI 9960) | |
| Shoal Cove | Alaska | Canadian West Coast (GRI 5990) / Gulf of Alaska (GRI 7960) | |
| Soustons | France | Lessay (GRI 6731) | |
| Tok | Alaska | Gulf of Alaska (GRI 7960) | |
| Tokachibuto | Japan | Eastern Russia Chayka (GRI 7950) / North West Pacific (GRI 8930) | |
| Upolo Point , Hawaii | United States | Italy | |
| Værlandet | Norway | Sylt (GRI 7499) / Ejde (GRI 9007) | |
| Veraval | India | Bombay (GRI 6042) | |
| Williams Lake | Canada | Canadian West Coast (GRI 5990) | |
| Xuancheng | China | China North Sea (GRI 7430) / China East Sea (GRI 8930) | |
| Yap | Micronesia | 1987 shut down, dismantled | used a 304.8 meter high antenna tower |
future
The continued existence of the LORAN-C system is under discussion worldwide, as satellite navigation systems are a much more accurate alternative; LORAN-C cannot compete with modern requirements in the meter and sub-meter range. Due to the propagation properties of the waves, z. B. an exact determination of the signal path extremely difficult. Already, the system finds in aviation - also because of its uncertainty and because of higher air traffic volume just above the North Atlantic and the associated increase in required navigational accuracy - no practical application more.
However, due to its signal characteristics, LORAN-C can be used complementary to GPS. The long-wave LORAN-C signal also penetrates where satellite reception is not possible due to a lack of direct line of sight to the satellites (e.g. in the forest, limited under water, between tall buildings). LORAN-C offers a simple integrity test, 'blinking', to warn the user in the event of malfunctions. Targeted interference with the signal emitted with high transmission power is also very difficult, in contrast to satellite-based methods. Another advantage of the system is that it is not under military control like GPS. Because of these properties, LORAN-C has been the subject of more discussion in recent years, especially as a backup system for GPS. Due to many studies that have shown many of the above-mentioned weaknesses of GPS as the only navigation system, an improved successor system under the name eLORAN is under discussion both in the USA and in Europe .
The last station of the US Coast Guard ceased its service on September 1, 2010. Europe is also in a state of upheaval when it comes to LORAN-C. The NELS contract expired at the end of 2005. However, contrary to what was announced, all European channels are still in operation (as of March 2007). Development in Europe is currently being driven primarily by Great Britain and France. The future is open, but a complete shutdown of the broadcasters is unlikely. It is most likely to operate within the European Union.
Eurofix
Eurofix expands Loran-C by a data channel over which GPS correction signals, UTC time signals and other data are transmitted. In the Eurofix feasibility phase , the stations Lessay, Sylt (until December 31, 2015), Værlandet and Bø Eurofix are currently available. The development of Eurofix has been driven by the Delft University of Technology since 1989 . Together with the correction data (DGNSS), the accuracy is better than 5 meters for 95 percent of the information.
eLORAN
The further development resulted in eLORAN (enhanced LORAN). Similar to GPS, eLORAN transmits its own correction data, the so-called additional secondary factors ( ASF ). They describe a weather-dependent terrain model that corrects the near-ground propagation behavior of long-wave radio waves. eLORAN achieves an accuracy of 10 m and better. It is on the order of GPS but does not provide altitude resolution. In return, it has the advantages of LORAN-C, such as high interference immunity.
eLORAN was set up by the General Lighthouse Authorities of the United Kingdom and Ireland (GLA), as well as by the USA as a complementary system to GPS. Operations ceased on December 31, 2015.
Similar systems
The Russian counterpart to LORAN-C is CHAYKA .
Other systems for (ground-based) radio navigation were and are Decca , OMEGA and Alpha .
attachment
supporting documents
- ↑ https://www.elwis.de/DE/dynamisch/BfS/index.php?target=3&source=1&aboexport=abo&db_id=122116
- ↑ GLA appreciates US decision for eLoran ( page no longer available , search in web archives ) Info: The link was automatically marked as defective. Please check the link according to the instructions and then remove this notice.
- ↑ Notice To Mariners - Region E - 27/2015 - Enhanced LORAN
literature
- Nathaniel Bowditch : The American Practical Navigator. An Epitome of Navigation. Bicentennial Edition. National Imagery and Mapping Agency, Bethesda MD 2002, ISBN 0-939837-54-4 , pp. 173ff. ( United States. National Imagery and Mapping Agency. Publication 9).
Web links
- www.loran.org - International LORAN Association (ILA)
- LORAN-C General Information - USCG Navigation Center
- Commissioners of Irish Lights: LORAN-C FAQ
- Description of the LORAN signal
- www.seefunknetz.de
- PLC
- SDR in action: The last LORAN-C receiver - self-made LORAN-C receiver
- Presentation of various legacy systems of hyperbolic (Engl.)