E Navigation.

[DJE]

Was anybody else at this talk last night? Trinity House and the other lighthouse authorites are promoting eLoran as a back up to GPS. They did a GPS jamming trial at Flamborough Head with a 1.5 watt transmitter and jammed the signal out to about 30km. So they're worried about the vulnerability of GPS.
One of the questioners at the end said that the military liked GPS because it is easy to jam as a defensive measure. They don't like eLoran because it's high power transmisions are difficult to jam, and the transmitters are not under the control of a single country, making it difficult to deny it's use to an enemy. You can't please everybody.

 

[shmoo]

That's all very well but it wouldn't stop our government turning off our eLoran the moment the Americans told them to. I can't imagine Trinity House having much say in the face of American orders/perceived terrorist threat/research showing that swine flu uses radio waves to navigate by.

 

[DaveS]

An entirely independent back up electronic navigation system makes lots of sense. We used to have one - until the (daft IMHO) decision was made to switch off Decca.

 

[grumpy_o_g]

[ QUOTE ]
One of the questioners at the end said that the military liked GPS because it is easy to jam as a defensive measure.

[/ QUOTE ]

He almost got it right. Military strategists like GPS because it can be switched off or jammed. Unfortunately quite a lot of the military who actually have to go to war have got quite used to using it to find their way around.

 

[charles_reed]

[ QUOTE ]
An entirely independent back up electronic navigation system makes lots of sense. We used to have one - until the (daft IMHO) decision was made to switch off Decca.

[/ QUOTE ]

The choice had to be made, between Decca with limited range, needing a lot of transmitters and doubtful accuracy and Loran with much better propagation characteristics, far fewer transmitters and world-wide coverage.
I'm sure, with the facts, you'd have made the same decision.

I wonder, however, how todays' navigators with their 15' accuracy with GPS would get on with loran with its highly variable and sometimes 15nm accuracy?

 

[charles_reed]

[ QUOTE ]
That's all very well but it wouldn't stop our government turning off our eLoran the moment the Americans told them to. I can't imagine Trinity House having much say in the face of American orders/perceived terrorist threat/research showing that swine flu uses radio waves to navigate by.

[/ QUOTE ]

You only need 3 within-range stations to get an adequate fix and from this list you'll note none of the serving transmitters for Loran-C are in the UK. In fact, they're so internationally spread that I doubt the US could coordinate action.

And then there's always CHAYKA...

List of LORAN-C transmitters (from Wikipedia)

A list of LORAN-C transmitters. Stations with an antenna tower taller than 300 metres (984 feet) are shown in bold.
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)
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[10]
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) [show location on an interactive map] 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) [show location on an interactive map] 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) [show location on an interactive map] 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 [show location on an interactive map] 46°46′32.286″N 53°10′27.606″W / 46.775635°N 53.174335°W / 46.775635; -53.174335 (Cape Race (LORAN))
Caribou, Maine United States Canadian East Coast (GRI 5930) / Northeast U.S. (GRI 9960) [show location on an interactive map] 46°48′27″N 67°55′37″W / 46.8075°N 67.92694°W / 46.8075; -67.92694 (Caribou (LORAN))
Carolina Beach, North Carolina United States Northeast US (GRI 9960)/ Southeast U.S. (GRI 7980) [show location on an interactive map] 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) [show location on an interactive map] 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) [show location on an interactive map] 49°19′53.57″N 54°51′42.57″W / 49.3315472°N 54.861825°W / 49.3315472; -54.861825 (Comfort Cove (LORAN))
Dana, Indiana United States Great Lakes (GRI 8970)/ Northeast US (GRI 9960) [show location on an interactive map] 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) [show location on an interactive map] 23°00′14″N 71°31′39″E / 23.00389°N 71.5275°E / 23.00389; 71.5275 (Dhrangadhra (LORAN))
Diamond Harbor India Calcutta (GRI 5543) [show location on an interactive map] 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) [show location on an interactive map] 39°33′06.740″N 118°49′55.816″W / 39.5518722°N 118.83217111°W / 39.5518722; -118.83217111 (Fallon (LORAN))
Fox Harbour Canada Labrador East Coast (GRI 7270)/ Canadian East Coast (GRI 5930) [show location on an interactive map] 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) [show location on an interactive map] 47°03′48.096″N 119°44′38.976″W / 47.06336°N 119.74416°W / 47.06336; -119.74416 (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) [show location on an interactive map] 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) [show location on an interactive map] 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) [show location on an interactive map] 48°44′38.589″N 109°58′53.613″W / 48.7440525°N 109.98155917°W / 48.7440525; -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) [show location on an interactive map] 27°01′58.528″N 080°06′52.875″W / 27.03292444°N 80.1146875°W / 27.03292444; -80.1146875 (Jupiter (LORAN))
Kargaburan Turkey Mediterranean Sea (GRI 7990); shut down
Kwang Ju South Korea East Asia (GRI 9930) [show location on an interactive map] 35°2′24″N 126°32′27″E / 35.04°N 126.54083°E / 35.04; 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) [show location on an interactive map] 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) [show location on an interactive map] 30°59′38.870″N 085°10′08.751″W / 30.99413056°N 85.1690975°W / 30.99413056; -85.1690975 (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) [show location on an interactive map] 41°15′12″N 69°58′39″W / 41.25333°N 69.9775°W / 41.25333; -69.9775 (Nantucket (LORAN))
Narrow Cape, Alaska United States North Pacific (GRI 9990) / Gulf of Alaska (GRI 7960) [show location on an interactive map] 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) [show location on an interactive map] 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) [show location on an interactive map] 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 [show location on an interactive map] 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) [show location on an interactive map] 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) [show location on an interactive map] 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) [show location on an interactive map] 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) [show location on an interactive map] 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) [show location on an interactive map] 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) [show location on an interactive map] 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 [show location on an interactive map] 38°52′21″N 16°43′7″E / 38.8725°N 16.71861°E / 38.8725; 16.71861 (Sellia Marina (LORAN))
Seneca, New York United States Great Lakes (GRI 8970)/Northeast U.S. (GRI 9960) [show location on an interactive map] 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) [show location on an interactive map] 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) [show location on an interactive map] 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) [show location on an interactive map] 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) [show location on an interactive map] 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) [show location on an interactive map] 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) [show location on an interactive map] 51°57′58.876″N 122°22′01.686″W / 51.96635444°N 122.367135°W / 51.96635444; -122.367135 (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

[edit] See also

 

[nimbusgb]

[ QUOTE ]
An entirely independent back up electronic navigation system makes lots of sense. We used to have one - until the (daft IMHO) decision was made to switch off Decca.

[/ QUOTE ]

Why does it have to be electronic? Eyeball MkI and paper charts. Totally impervious to battery supply failure, external electronic jamming or other external influences except fatigue and alcohol.

For years i navigated sailplanes like this covering thousands of kilometres.

I find the argument that GPS is vulnerable to jamming or turning off by the military completely nuts.

1 - By an act of congress GPS cannot be turned off ( too many depend on it )

2 - If for some completely off the wall reason ie there is a major world war, and congress say ok you can turn it off are you really going to be swanning around on your little boat / car /plane worried about where you are on your holiday? No you'll be sitting in your living room, scared and watching the telly.Remember this is a MAJOR conflict and won't have started over the past hour or so!

3 - Some terrorist organisation decides to jam GPS ( for what reason only you may know ). in this scenario I admit it may be an hour or two before a Tornado / Harrier / Eurofighter / F-18 or B2B is dispatched to 'turn off' the source of the signal.

Backup? Do as mandated, take a chart, keep DR and plot your position. Hey once in a while go sailing and don't turn on the GPS at all.

 

[DaveS]

WADR that is a different argument. Yes, I too navigated by traditional means before having Decca then GPS, and yes I still can - when conditions allow. And that's the point. Given reasonable visability, traditional pilotage techniques can fix your position with adequate accuracy, albeit at some cost of spending time below drawing lines rather than watching what's going on. In murky weather - not just fog, but low cloudbase, heavy rain, etc. - it can often be far from clear e.g. which headland is in view. At such times an electronic fix, even with say 0.5 nm uncertainty, transforms the situation.

 

[DJE]

[ QUOTE ]
3 - Some terrorist organisation decides to jam GPS ( for what reason only you may know ). in this scenario I admit it may be an hour or two before a Tornado / Harrier / Eurofighter / F-18 or B2B is dispatched to 'turn off' the source of the signal.

[/ QUOTE ]That's not what the lady from Trinity House said. There have been incidents of faulty tv sets emitting jamming signals and even one of Trinity House's own tenders had a faulty antenna cable which was jamming GPS. In all these cases it took days to find the source of the problem.

 

[smartcom]

Loran C and eLoran are totally differernt - receivers for one won't ork with the other, as the signals are different. There are already a few eLoran stations transmitting in Europe, and Trinity House and others are campaigning to have it rolled out over Europe.
Compared to the old Loran, it is much more accurate (about 10 metres) partly because it effectively includes differential type corrections within the signal, it reads out lat/long directly, and no need to worry about chains any more, it uses whatever transmitters it can find.