OT: GPS Blocking Exercise Cornwall June 2007

Just a heads up:

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MoD set to block sat nav systems

People in Cornwall have been warned satellite navigation systems will not work later this week as the Ministry of Defence carry out a jamming exercise. The aim of the GPS blocking exercise is to find out how interference could affect military personnel. It will take place on Thursday and Friday.

The MoD said its Portreath base would be the base.

The effect will extend for a radius of 11 km (7 miles) which would cover Camborne and Redruth.

"Although GPS provides highly accurate information, the radio signals from the satellite are extremely weak and are susceptible to both jamming and unintentional radio interference," said the MOD in a statement.

"The trials are taking place to better understand these effects on military equipment and therefore will help to protect our forces."

An MOD spokesman said all the emergency services which might use the systems have been informed and if an emergency is under way, the MOD can suspend the trial.

All ambulances are fitted with satellite navigation and in a statement, South Western ambulance service said it was aware of the jamming exercise and that key staff had been informed.

Falmouth Coastguard said it had also been told.

Reply to
Fred
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Interesting that - when we were invading Iraq - about half an hour before the first main attack, my GPS went down and refused to plot position until about an hour later - during this time no satellite at all was "available". Got home and then heard on the news about the attack.

Now is this coincidence, or has jamming been used before without telling us beforehand?????

Reply to
David J. Button

"available".

It would be very suprising if it hadn't, after all the satellites were put there by the military for their use, civvy use being incidental.

AWEM

Reply to
Andrew Mawson

Why would the Americans want to Invade Cornwall? Is there Oil in them there pasties?

;-)

Lee D

Reply to
Lee_D

I don't know about coincidence, or jamming in this case, I wasn't using a system at the time, but they've always been able to selectively degrade the civilian signal since the days of the Gulf War. I daresay turning it off & leaving the encrypted military signal running is a matter of a few keystrokes.

It's one reason the EC are trying to get their own version in orbit as soon as possible.

During the Gulf war, you could, according to some boating friends of mine, watch the boat's reported position wander up to about 100 metres while you were tied up to a jetty. After the Gulf war, they could use the same set on the same boat to come alongside the same mooring without looking at anything apart from the GPS screen. It was one reason a lot of airports now use differential GPS, with a transmitter broadcasting the difference between the known position and the calculated position of a fixed receiver every few seconds.

Tciao for Now!

John.

Reply to
John Williamson

message

message

position

incidental.

Obvious Lee - really, as a trained copper you should know these things - there is a Pasty shortage in the US

AWEM

Reply to
Andrew Mawson

My local supermarket may be to blame, it sells a mediterranean mix of olives and vegetables called anti-pasty, this is plainly destroying the native pasties. Tony Blair will announce some new laws tomorrow, and today, and on Friday, and next Monday, and Tuesday.

Reply to
Ian Rawlings

tomorrow,

...nah ... he's too busy spending our money going on farewell trips before his snout is pulled out of the trough !

AWEM

Reply to
Andrew Mawson

"Ian Rawlings" wrote >> Obvious Lee - really, as a trained copper you should know these

I've always wondered, if you eat pasta followed by anti-pasta, would you still be hungry?

- Tom.

Reply to
Tom Bennett

You cannae change the laws of physics laddie - if you mix Pasta and Anti Pasta outside of a warp engine chamber ye'll be blown to kingdom come Derek Klingons on the starboard bow captain

Reply to
Derek

It was part of the orginal spec, not something added at a later date. Not long after Gulf War I the US decided to permenantly turn Selective Availabilty off and leave it off.

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Between the lines: The switching on of SA gave the game away to anyone watching that the US military where probably "up to something". A lot of the troops on the ground in GWI had their own "civilian" GPS units rather than the expensive mil ones, with SA enabled it handicapped their own troops.

Reply to
Dave Liquorice

On or around Tue, 05 Jun 2007 18:56:28 +0100, John Williamson enlightened us thusly:

I gather they turned off selective availability when they found that there was a shortage of the special receivers that could decode it, and the troops took to using civvy GPS uints which were available and worked.

BICBW.

But I bet the system is still in place to be turned on again if they want.

Reply to
Austin Shackles

Interesting quote from that source:-

"Additionally, we have demonstrated the capability to selectively deny GPS signals on a regional basis when our national security is threatened. This regional approach to denying navigation services is consistent with the 1996 plan to discontinue the degradation of civil and commercial GPS service globally through the SA technique."

I also notice they only say they're discontinuing the use of the SA facility, not removing it altogether.

Reply to
John Williamson

Just shows you never to trust them in the first place.

Eventually they will all be screwed by a big solar flare anyway, but don't go looking for your compass as an alternative, that just might be the same day as the magnetic field flips aswell ...

Reply to
Larry

Just shows you never to trust them in the first place.

Eventually they will all be screwed by a big solar flare anyway, but don't go looking for your compass as an alternative, that just might be the same day as the magnetic field flips aswell ...

Reply to
Larry

Larry uttered summat worrerz funny about:

Back to the stars then eh!

Which is OK if you are on a long slow trip with no cloud. :-)

Ray Mears mentioned that the handle end of the PLough points towards the North star. Interesting stuff!

Lee D

Reply to
Lee_D

You can also use the old wristwatch method, problem is what you do changes depending on whether you are in the north hemisphere or the south, and I can never remember which way round it goes so I can tell you that a particular direction is either north or south but not which one!

A good book to get is the rather cheesily named SAS Survival Guide from Collins Gem, very compact book packed with useful info including how to navigate using the stars, wristwatches, birds, plants etc etc.

Reply to
Ian Rawlings

including

....nah .... every boy scout knows that you look for the moss on the east side of tree trunks then turn 90 degrees !

AWEM

Reply to
Andrew Mawson

Interesting indeed as it's the right hand two of the blade that point towards Polaris... Which is a rather dim star at roughly 4 times the distance between the two "pointer" stars.

  • ** ^ To Polaris * I
    • *
  • *

Watch navigation, point the hour hand at the azimuth(*) of the sun and 12 points south in the northern hemisphere, north in the southern. You also need to compensate for any daylight savings, probably easiest to use 1 instead of 12 if daylight savings are in operation.

(*) How far around the horizon the sun is.

Reply to
Dave Liquorice

On or around Wed, 6 Jun 2007 20:56:56 +0100, "Lee_D" enlightened us thusly:

If you look at the plough as a saucepan, then the handle doesn't. I'm not sure which end is the handle when it's being a plough.

Reply to
Austin Shackles

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