الملاحة بعيدة المدى

الملاحة البعيدة المدى وتُسمّى أيضًا لوران LORAN (LOng Range Aid to Navigation) هو نظام ملاحة راديوية أرضي يستخدم إرساليات راديوية ذات تردد منخفض تستعمل عدة إرساليات (multilateration) لتحديد موقع و/أو سرعة المستقبل. وهي نظام ملاحي راديوي يساعد السفن والطائرات على تحديد مواقعها. وترسل محطتان أو أكثر تعرفان باسم المحطة الرئيسية والمحطة التابعة الإشارات الراديوية باستمرار، وتستقبل السفينة أوالطائرة هذه الإشارات من خلال أجهزة خاصة. وتقوم هذه الأجهزة بقياس الفترة الزمنية بين النبضات التي تلتقطها من المحطات. ويحدد الفرق في الزمن بين الإشارات التي تلتقطها من محطتين، موقع السفينة أو الطائرة فوق نقطة ما على خط الموقع اللوراني فوق الخريطة. وتوضع علامة على الخريطة لتحديد موقع السفينة أو الطائرة طبقاً للفرق في الزمن بين الإشارات المرسلة من المحطتين.

وفي معظم الحالات، نجد محطة راديوية رئيسية واحدة يقابلها محطة راديوية تابعة من إحدى محطتي التوابع، حيث يسمح هذا الترتيب للملاح أن يقطع خطي موقع لوراني، ليحدد موقع سفينة أو طائرة وبذلك يحسِّن بدرجة كبيرة من دقة نظام الملاحة.

ويستخدم الملاحون نظامًا راديويًا يُعرف باسم لوران ـ سي يستطيع أن يرسل إشارات تقطع 1,600 كم أثناء النهار. وفي بعض الظروف، يصل مداها إلى أكثر من 4,800 كم أثناء الليل عندما تنتقل موجات الراديو منخفضة التردد إلى مسافات أبعد، وبذلك يمكن تحديد أي موقع داخل مدى حوالي نصف كيلومتر.

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Principle

A crude diagram of the LORAN principle. The difference between the time of receiption of synchronized signals from radio stations A and B is constant along each hyperbolic curve.^{[بحاجة لمصدر]} When demarcated on a map, such curves are known as "TD lines".

LORAN method

LORAN pulse

LORAN chains (GRIs)

LORAN Station Malone, Malone, Florida Great Lakes chain (GRI 8970) / Southeast U.S. chain (GRI 7980)

LORAN charts

This nautical chart of نيويورك Harbor includes LORAN-A TD lines. Note that the printed lines do not extend into inland waterway areas.

Timing and Synchronization

Caesium atomic clocks

Transmitters and antennas

LORAN transmitter bank

انظر أيضاً: الملاحة؛ الشوران.

قائمة إرساليات LORAN-C

A list of LORAN-C transmitters. Stations with an antenna tower taller than 300 metres (984 feet) are shown in bold.

المحطة	البلد	السلسلة	تعليق
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)
Angissq	Greenland	shutdown on December 31, 1994	used until July 27, 1964 a 411.48 metre tower
Anthorn	UK	Lessay (GRI 6731)	replacement for transmitter Rugby^[1]
Ash Shayk	Saudi Arabia	Saudi Arabia South (GRI 7030)/Saudi Arabia North (GRI 8830)
Attu, Alaska	United States	North Pacific (GRI 9990)/Russian-American (GRI 5980)	52°49′44.134″N 173°10′49.528″E / 52.82892611°N 173.18042444°E / 52.82892611; 173.18042444 (Attu (LORAN))
Balasore	India	Calcutta (GRI 5543)
Barrigada	Guam	shut down
Baudette, Minnesota	United States	North Central U.S. (GRI 8290)/Great Lakes (GRI 8970)	48°36′49.947″N 94°33′17.915″W / 48.61387417°N 94.55497639°W / 48.61387417; -94.55497639 (Baudette (LORAN))
Berlevåg	Norway	Bø (GRI 7001)
Billamora	India	Bombay (GRI 6042)
Boise City, Oklahoma	United States	Great Lakes (GRI 8970)/South Central U.S. (GRI 9610)	36°30′21″N 102°53′59″W / 36.50583°N 102.89972°W / 36.50583; -102.89972 (Boise City (LORAN))
Bø, Vesterålen	Norway	Bø (GRI 7001)/Eiði (GRI 9007)
Cambridge Bay	Canada	shut down	free-standing lattice tower, used as NDB
Cape Race	Canada	Canadian East Coast (GRI 5930)/Newfoundland East Coast (GRI 7270)	used a 411.48 metre tall tower until February 2, 1993, uses now a 260.3 metre tall tower 46°46′32.286″N 53°10′27.606″W / 46.77563500°N 53.17433500°W / 46.77563500; -53.17433500 (Cape Race (LORAN))
Caribou, Maine	United States	Canadian East Coast (GRI 5930) / Northeast U.S. (GRI 9960)	46°48′27″N 67°55′37″W / 46.80750°N 67.92694°W / 46.80750; -67.92694 (Caribou (LORAN))
Carolina Beach, North Carolina	United States	Northeast US (GRI 9960)/ Southeast U.S. (GRI 7980)	34°3′46″N 77°54′46″W / 34.06278°N 77.91278°W / 34.06278; -77.91278 (Carolina Beach (LORAN))
Chongzuo	China	China South Sea (GRI 6780)	22°32′35″N 107°13′22″E / 22.54306°N 107.22278°E / 22.54306; 107.22278 (Chongzuo (LORAN))
Comfort Cove	Canada	Newfoundland East Coast (GRI 7270)	49°19′53.57″N 54°51′42.57″W / 49.3315472°N 54.8618250°W / 49.3315472; -54.8618250 (Comfort Cove (LORAN))
Dana, Indiana	United States	Great Lakes (GRI 8970)/ Northeast US (GRI 9960)	39°51′07.658″N 87°29′11.586″W / 39.85212722°N 87.48655167°W / 39.85212722; -87.48655167 (Dana (LORAN))
Dhrangadhra	India	Bombay (GRI 6042)	23°00′14″N 71°31′39″E / 23.00389°N 71.52750°E / 23.00389; 71.52750 (Dhrangadhra (LORAN))
Diamond Harbor	India	Calcutta (GRI 5543)	22°10′18″N 88°12′25″E / 22.17167°N 88.20694°E / 22.17167; 88.20694 (Diamond Harbor (LORAN))
Eiði	Faroe Islands	Ejde (GRI 9007)
Estartit	Spain	Mediterranean Sea (GRI 7990); shut down
Fallon, Nevada	United States	U.S. West Coast (GRI 9940)	39°33′06.740″N 118°49′55.816″W / 39.55187222°N 118.83217111°W / 39.55187222; -118.83217111 (Fallon (LORAN))
Fox Harbour	Canada	Labrador East Coast (GRI 7270)/ Canadian East Coast (GRI 5930)	52°22′35.252″N 55°42′27.862″W / 52.37645889°N 55.70773944°W / 52.37645889; -55.70773944 (Fox Harbour (LORAN))
George, Washington	United States	Canadian West Coast (GRI 5990)/ U.S. West Coast (GRI 9940)	47°03′48.096″N 119°44′38.976″W / 47.06336000°N 119.74416000°W / 47.06336000; -119.74416000 (George (LORAN))
Gesashi	Japan	East Asia (GRI 9930)/ North West Pacific (GRI 8930)
Gillette, Wyoming	United States	South Central U.S. (GRI 9610)/ North Central U.S. (GRI 8290)	44°00′11.305″N 105°37′23.895″W / 44.00314028°N 105.62330417°W / 44.00314028; -105.62330417 (Gillette (LORAN))
Grangeville, Louisiana	United States	South Central U.S. (GRI 9610)/ Southeast U.S. (GRI 7980)	30°43′33.149″N 090°49′43.046″W / 30.72587472°N 90.82862389°W / 30.72587472; -90.82862389 (Grangeville (LORAN))
Havre, Montana	United States	North Central U.S. (GRI 8290)	48°44′38.589″N 109°58′53.613″W / 48.74405250°N 109.98155917°W / 48.74405250; -109.98155917 (Havre (LORAN))
Hellissandur	Iceland	shut down on December 31, 1994	411.48 metre tall tower, now used for longwave broadcasting of RÚV on 189 kHz
Helong	China	China North Sea (GRI 7430)
Hexian	China	China South Sea (GRI 6780)
Jan Mayen	Norway	Bø (GRI 7001)/ Ejde (GRI 9007)
Johnston Island	United States	shut-down
Iwo Jima	Japan	shut down in September 1993, dismantled	used a 411.48 metre tall tower
Jupiter, Florida	United States	Southeast U.S. (GRI 7980)	27°01′58.528″N 080°06′52.875″W / 27.03292444°N 80.11468750°W / 27.03292444; -80.11468750 (Jupiter (LORAN))
Kargaburan	Turkey	Mediterranean Sea (GRI 7990); shut down
Kwang Ju	South Korea	East Asia (GRI 9930)	35°2′24″N 126°32′27″E / 35.04000°N 126.54083°E / 35.04000; 126.54083 (Kwang Ju (LORAN))
Lampedusa	Italy	Mediterranean Sea (GRI 7990); shut down
Las Cruces, New Mexico	United States	South Central U.S. (GRI 9610)	32°4′18″N 106°52′4″W / 32.07167°N 106.86778°W / 32.07167; -106.86778 (Las Cruces (LORAN))
Lessay	France	Lessay (GRI 6731) / Sylt (GRI 7499)
Loop Head	Ireland	was planned (GRI 6731 and 9007), but never operational
Malone, Florida	United States	Great Lakes (GRI 8970) / Southeast U.S. (GRI 7980)	30°59′38.870″N 085°10′08.751″W / 30.99413056°N 85.16909750°W / 30.99413056; -85.16909750 (Malone (LORAN))
Minamitorishima	Japan	North West Pacific (GRI 8930)	used until 1985 a 411.48 metre tall tower
Nantucket, Massachusetts	United States	Canadian East Coast (GRI 5930) / Northeast U.S. (GRI 9960)	41°15′12″N 69°58′39″W / 41.25333°N 69.97750°W / 41.25333; -69.97750 (Nantucket (LORAN))
Narrow Cape, Alaska	United States	North Pacific (GRI 9990) / Gulf of Alaska (GRI 7960)	57°26′20″N 152°22′11″W / 57.43889°N 152.36972°W / 57.43889; -152.36972 (Narrow Cape (LORAN))
Niijima	Japan	North West Pacific (GRI 8930) / East Asia (GRI 9930)	34°24′12″N 139°16′19″E / 34.40333°N 139.27194°E / 34.40333; 139.27194 (Niijima (LORAN))
Patpur	India	Calcutta (GRI 5543)
Pohang	South Korea	North West Pacific (GRI 8930) / East Asia (GRI 9930)	36°11′5″N 129°20′27″E / 36.18472°N 129.34083°E / 36.18472; 129.34083 (Pohang (LORAN))
Port Clarence, Alaska	United States	Gulf of Alaska (GRI 7960)/North Pacific (GRI 9990)	uses a 411.48 metre tall tower 65°14′40.372″N 166°53′11.996″W / 65.24454778°N 166.88666556°W / 65.24454778; -166.88666556 (Port Clarence (LORAN))
Port Hardy	Canada	Canadian West Coast (GRI 5990)	50°36′29.830″N 127°21′28.489″W / 50.60828611°N 127.35791361°W / 50.60828611; -127.35791361 (Port Hardy (LORAN))
Rantum	Germany	Sylt (GRI 7499)/ Lessay (GRI 6731)
Raymondville, Texas	United States	South Central U.S. (GRI 9610)/ Southeast U.S. (GRI 7980)	26°31′55″N 97°50′0″W / 26.53194°N 97.83333°W / 26.53194; -97.83333 (Raymondville (LORAN))
Raoping	China	China South Sea (GRI 6780)/ China East Sea (GRI 8930)	23°43′26″N 116°53′45″E / 23.72389°N 116.89583°E / 23.72389; 116.89583 (Raoping (LORAN))
Rongcheng	China	China North Sea (GRI 7430)/ China East Sea (GRI 8930)	37°3′52″N 122°19′26″E / 37.06444°N 122.32389°E / 37.06444; 122.32389 (Rongcheng (LORAN))
Rugby	UK	experimental (GRI 6731); shut down at the end of July 2007
Saint Paul, Alaska	United States	North Pacific (GRI 9990)	57°09′12.350″N 170°15′06.245″W / 57.15343056°N 170.25173472°W / 57.15343056; -170.25173472 (Saint Paul (LORAN))
Salwa	Saudi Arabia	Saudi Arabia North (GRI 8830)/Saudi Arabia South (GRI 7030)
Searchlight, Nevada	United States	U.S. West Coast (GRI 9940)/South Central U.S. (GRI 9610)	35°19′18.305″N 114°48′16.881″W / 35.32175139°N 114.80468917°W / 35.32175139; -114.80468917 (Searchlight (LORAN))
Sellia Marina	Italy	Mediterranean Sea (GRI 7990); shut down	38°52′21″N 16°43′7″E / 38.87250°N 16.71861°E / 38.87250; 16.71861 (Sellia Marina (LORAN))
Seneca, New York	United States	Great Lakes (GRI 8970)/Northeast U.S. (GRI 9960)	42°42′51″N 76°49′33″W / 42.71417°N 76.82583°W / 42.71417; -76.82583 (Seneca (LORAN))
Shoal Cove, Alaska	United States	Canadian West Coast (GRI 5990)/Gulf of Alaska (GRI 7960)	55°26′21″N 131°15′19″W / 55.43917°N 131.25528°W / 55.43917; -131.25528 (Shoal Cove (LORAN))
Soustons	France	Lessay (GRI 6731)	43°44′23″N 1°22′50″W / 43.73972°N 1.38056°W / 43.73972; -1.38056 (Soustons (LORAN))
Tok, Alaska	United States	Gulf of Alaska (GRI 7960)	63°19′42.884″N 142°48′31.346″W / 63.32857889°N 142.80870722°W / 63.32857889; -142.80870722 (Tok (LORAN))
Tokachibuto	Japan	Eastern Russia Chayka (GRI 7950)/ North West Pacific (GRI 8930)	42°44′37″N 143°43′10″E / 42.74361°N 143.71944°E / 42.74361; 143.71944 (Tokachibuto (LORAN))
Upolo Point, Hawaii	United States	shut-down
Værlandet	Norway	Sylt (GRI 7499)/ Ejde (GRI 9007)
Veraval	India	Bombay (GRI 6042)	20°57′7″N 70°20′13″E / 20.95194°N 70.33694°E / 20.95194; 70.33694 (Veraval (LORAN))
Williams Lake	Canada	Canadian West Coast (GRI 5990)	51°57′58.876″N 122°22′01.686″W / 51.96635444°N 122.36713500°W / 51.96635444; -122.36713500 (Williams Lake (LORAN))
Xuancheng	China	China North Sea (GRI 7430)/ China East Sea (GRI 8930)
Yap	Micronesia	shut down in 1987, dismantled	used a 304.8 metre tall tower

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انظر أيضاً

CHAYKA, the Russian counterpart of LORAN
Alpha, the Russian counterpart of the Omega Navigation System, still in use as of 2006.
OMEGA, the Western counterpart of the Alpha Navigation System, no longer in use.
Decca Navigator System, a British system that used phase difference instead of time difference.
SHORAN
Oboe (navigation)
G-H (navigation)
GEE (navigation)
GPS

الهامش

^ "Electronic Position Fixing System" (PDF). Admiralty Notices to Mariners. United Kingdom Hydrographic Office (26/07). 2007-06-28. Retrieved 2008-01-19. {{cite journal}}: Check date values in: |date= (help); Cite has empty unknown parameter: |coauthors= (help)

Jennet Conant, Tuxedo Park: A Wall Street Tycoon and the Secret Palace of Science That Changed the Course of World War II (New York: Simon & Schuster, 2002, ISBN 0-684-87287-0) pp. 231-232.
Department of Transportation and Department of Defense (2006-02). "2005 Federal Radionavigation Plan" (PDF). Retrieved 2006-02-26. {{cite web}}: Check date values in: |year= (help); Cite has empty unknown parameter: |accessyear= (help)

وصلات خارجية

The Case for LORAN- It is a good backup, and very accurate.
United States Coast Guard's official site- how to use LORAN C
9th Pulse Modulation / LORAN Data Channel (LDC) - will provide information using pulse position modulation of the broadcast signal.
United States National Institute of Standards and Technology Site- Using LORAN C for time-keeping.
LORAN-C Transmitter (Rantum) in the Structurae database
Hellissandur Transmission Tower in the Structurae database
former LORAN-C transmitter mast, now used for longwave broadcasting
LORAN-C facility antenna (Gillette, Wyoming) in the Structurae database
LORAN-C facility antenna (Port Clarence, Alaska) in the Structurae database
http://www.jproc.ca/hyperbolic/loran_a.html More in-depth discussion of the Loran-A system.
http://www.jproc.ca/hyperbolic/loran_b_d.html Histories of Lorans-B, -D, and "-F".
Integrated GPS/Loran Prototypes for Aviation Applications
Loran-C Introduction: eLoran
The Migration to Enhanced or eLoran
The Case for eLoran at GPS World
GNSS/eLoran for Timing and Frequency by Locus, Inc.
Loran's Capability to Mitigate the Impact of a GPS Outage on GPS Position, Navigation, and Time Applications by Locus, Inc.
New Potential of Low-Frequency Radionavigation in the 21st Century Ph.D. dissertation
LORAN-C chains in service
List of active LORAN-C transmitters
SDR in action: The last LORAN-C receiver is a technical description of using a software-defined radio to decode LORAN-C signals.
New UK eLORAN service provision news article News article re: UK leading the way in eLORAN service provision.
eLORAN vs Loran-C at InsideGNSS - Short article describing the innovations in eLORAN.
History of LORAN

[1] "Electronic Position Fixing System" (PDF). Admiralty Notices to Mariners. United Kingdom Hydrographic Office (26/07). 2007-06-28. Retrieved 2008-01-19. {{cite journal}}: Check date values in: |date= (help); Cite has empty unknown parameter: |coauthors= (help)

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