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Old 04 February 2008, 12:11   #1
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GPS Jamming in April

The following GPS jamming exercises, planned by the MoD have been publicised by Ofcom:

Dates: 31 March to 4 April 2008
Times: between 08:00 and 18:00 hrs
Location: To sea from Bridlington - N54° 06.842’ W000° 05.045’
Contact: Trial Manager - 07766 134758

Dates: 20-21 April 2008 (26 April 2008 reserve day)
Times: between 09:00 and 17:00 hrs
Location: To sea from The Hebrides - N57° 14.4’ W007° 26.7’
Contact (during jamming exercise only) 07766 134520

Details of the trials are "restricted", but the government has said that the trials are intended to research "vulnerabilities in a range of military applications" of satellite navigation, although is has also been noted that the Defence Science and Technology Laboratory PR team have denied that such trial are taking place!
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Old 04 February 2008, 12:36   #2
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Once upon a time they said it couldn't be jammed..........
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Old 04 February 2008, 13:20   #3
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Perhaps it couldn't. Perhaps they can't. Perhaps they're trying again.
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Old 04 February 2008, 13:25   #4
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Oh it can alright - sometimes by accident!!!
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Old 04 February 2008, 15:56   #5
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This is probably a silly question...

...but given the coordinates

Location: To sea from The Hebrides - N57° 14.4’ W007° 26.7’

it all seems a bit 'woolly' to me. How far out to sea? In any particular direction? Or 360°?

I haven't got a chart for there - it is S. Uist isn't it?

I presume the technicalities involve lots of 'noise' on the correct wavelength or something? Are there any people who know stuff knocking about out there?

I think we should be told!

Then again, if it's not officially happening...

Paranoid? Me?
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Old 04 February 2008, 16:18   #6
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..I haven't got a chart for there - it is S. Uist isn't it?
Aye, it is.
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Old 04 February 2008, 17:26   #7
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it all seems a bit 'woolly' to me. How far out to sea? In any particular direction? Or 360°?
last time i think they were suggesting a 6 NM radius to be at risk. It could be more powerful this time?

The site is MoD land on the west of the island. Since GPS signals don't travel well through land I think you will be fine to the East of the island.

last time round the cg were making securite anouncements.
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Old 05 February 2008, 06:50   #8
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Since GPS signals don't travel well through land
Not meaning to be rude, just curious, but I'm not sure I follow the thinking here. The GPS signals are coming from satellites, so where is the land that they would have to travel through?
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Old 05 February 2008, 09:02   #9
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Not meaning to be rude, just curious, but I'm not sure I follow the thinking here. The GPS signals are coming from satellites, so where is the land that they would have to travel through?
I am assuming if you wish to Jam a GPS (or test technology for jamming or preventing jamming) you use a ground based transmitter to broadcast a jamming signal on the frequencies used for GPS. If you either broadcast false signals or relatively high powered noise you confuse the reciever. So that it can't recieve/process the satellite signals or so that it thinks it is getting signals from a satellite which it is not. Hence the effect would only be in a localised area within line of sight of the transmitter.

Does that make sense? I suppose you could try to block the satellite itself - but you would need to either block all the satelites in an area or make a satellite send the "incorrect" signal - and that seems a lot more difficult.
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Old 05 February 2008, 09:07   #10
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In that case why do the tests at sea? If the effect wanted is to send a different signal there's no need for it to be done at sea. The results can established on land.
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Old 05 February 2008, 09:22   #11
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In that case why do the tests at sea? If the effect wanted is to send a different signal there's no need for it to be done at sea. The results can established on land.
There are a whole load of possible reasons: (1) that is where the test range is (2) this is an unpopulated area where it is not going to upset the publics' tom-tom (3) the research may well be being sponsorred by the Navy [each MoD research project that DSTL/QinetiQ undertake has a "customer" within one or more armed forces] (4) they can ignore the effects of land on the results - a flat surface is easier to interpret the results from (5) they may be doing tests on land too - but the RYA publicised it for the interest of marine users (6) there are actually some big radio antannae in the viscinity so it may be they need/want to use those existing mast [not sure if they are owned by MoD or not - but it is certainly feasible]. (7) if they want to test the range of the effects they can just keep travelling out to sea - if it is on land and they get to the edge of their field they can't go any further (8) they may (?) be testing the effects on missile guidance systems. Not sure if the sea is an official firing range or not in that area.

I am sure there are others.
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Old 05 February 2008, 09:47   #12
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That's a pretty good answer
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Old 14 February 2008, 19:16   #13
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From the RYA website...

http://www.rya.org.uk/NewsAndEvents/...gpsjam4feb.htm

"Similar trials carried out for the Government, by the MOD have already taken place in a number of areas including Lincolnshire, Wales, Scotland and Cornwall have had an effect over a range of approximately 11km. Details of the trials are "restricted", but the government has said that the trials are intended to research "vulnerabilities in a range of military applications" of satellite navigation, although is has also been noted that the Defence Science and Technology Laboratory PR team have denied that such trial are taking place! For previous trials the Coastguard have locally broadcast details of the trial with timings and a Notice to Airmen was also published at least for the trial in Portreath, Cornwall.

GPS satellites transmit two low power radio signals, designated L1 and L2. Civilian GPS uses the L1 frequency of 1575.42 MHz in the UHF band. All radio navigation systems are susceptible to interference and environmental effects, which can adversely affect their availability. Because of the low power and Ultra High Frequency GPS is particularly susceptible to interference and even hostile jamming which is why the General Lighthouse Authorities are establishing a new Enhanced Loran (eLoran) station in Cumbria, UK (coordinates: Latitude 54° 54' 40.35'' N. Longitude 3° 17' 14.21'' W). It is hoped that this will be fully operational by the end January 2008.

The RYA strongly advises that no single aids to navigation system should be used in isolation and that users should use all alternative means available to cross check the information received."

So keep those paper charts and sextants handy!
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Old 14 February 2008, 23:14   #14
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They should go back to Decca!!!
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Old 15 February 2008, 04:26   #15
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Why?
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Old 15 February 2008, 06:26   #16
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So keep those paper charts and sextants handy!
I always assumed thats what they were doing.. getting the crew on exercise to navigate in conditions as if there were a gps system failure.

When GB TB and the other G8 attendees were at Gleneagles, a whole zone was shut off around the area. Presumably a satellite out put can be turned off too, preventing triangulation, rather than having to jam a signal.
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Old 15 February 2008, 07:54   #17
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I always assumed thats what they were doing.. getting the crew on exercise to navigate in conditions as if there were a gps system failure.

When GB TB and the other G8 attendees were at Gleneagles, a whole zone was shut off around the area. Presumably a satellite out put can be turned off too, preventing triangulation, rather than having to jam a signal.
Not sure they will be..switching or blanking off the GPS set for training purposes happens all the time, dont need to go to such extreme lengths to simulate failure
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