GPS Jamming Exercise at Portreath

[ORAC]

Just hope the Navy don't get lost....... :cool:

BBC: 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.

[themightyimp]

If you are in the Military, have you ever heard the term BEADWINDOW. Kermit...................

[Fluffy Bunny]

Yimp,
How can it be a beadwindow occurance when he is quoting from open source and public information given out by MoD to the locals round said airfield as to why their GPS won't work for a few days next week?

http://news.bbc.co.uk/1/hi/england/cornwall/6719639.stm

Foot, Mouth, .......:ugh:

[Another St Ivian]

As per the NOTAM;
AUS 07-06-0207/1706/AS2 GPS SIGNAL JAMMING TRIALS. GND JAMMER LOCATED WI 0.5 NM OF 5016N 00516W (PORTREATH, CORNWALL). ACTIVITY MAY AFFECT ACFT WI 6NM RADIUS FLYING BELOW FL300...

They ran a similar trial out of Sennybridge very recently, also well NOTAM'ed. Nothing untoward was noticed at all during the notified period even when flying well within the reported radiating area.

[Razor61]

They do it at Sennybridge quite regularly...

[Ex F111]

...and elsewhere around the world on a regular basis as part of mil exercises or just R & D. What is the big deal?? - Or are you soooo last century that you cannot tactically operate without said nav kit.

[vecvechookattack]

How does the MOD stand on a legal point if for instance someone who has paid a lot of money for his Tom Tom gets lost due to the GPS signal being jammed? Could argue the same point for a sailor in his Yacht getting lost.

[samuraimatt]

Then they should learn how to use a road map and nautical chart.

[diginagain]

I might be tempted to get the sextant out of it's box.





Or stay close to the pub.

TBH, I don't think my Cornish rellies will be much affected - they're still struggling with the concept of a dual-carriageway A30.

[airborne_artist]

How does the MOD stand on a legal point if for instance someone who has paid a lot of money for his Tom Tom gets lost due to the GPS signal being jammed?

MoD doesn't stand anywhere. Does the TomTom user have a contract and an SLA with the US DoD? No, so no problem.

[samuraimatt]

From the user manual. GPS is operated and controlled under the sole responsibility of the Government of the United States of America, who are responsible for its availability and accuracy. So if they don't stop the UK from jamming it then it's all their fault.

[Runaway Gun]

So apart from dropping a 2000 pounder on them, how exactly do you effectively stop someone jamming a GPS signal?

[Wader2]

meaconing .

[airborne_artist]

how exactly do you effectively stop someone jamming a GPS signal?

Just the way you said - you have to stop their re-broadcasting system from working, so take out any key component eg power, radio or antennae, or the lot!

[gar170]

Look on the bright side if your GPS is not working then you have a better chance of missing Camborne and Redruth altogether.
That can only be a good thing:D.

[vecvechookattack]

Why would you want to Jam GPS ? Surely it would deny your own forces of its capability

[ZH875]

Why would you want to Jam GPS ? Surely it would deny your own forces of its capability
Not if they are not operating in that area, but the EF are.:ugh:

[Wader2]

So apart from dropping a 2000 pounder on them, how exactly do you effectively stop someone jamming a GPS signal?

Oops, misread the post first time - dyslexic.

As the GPS receiver is very sensitive and uses only very weak signals a jamming signal does not have to be very powerful. Low powered transmitters could be very small and easy to hide, even from a 2000lb bomb.

Indeed several in an area could cause a GPS jammer-homing bomb to land in a 'safe' area.

[Roadster280]

Call me old fashioned, if you will, but the first defence to jamming is to change frequency. It would not surprise me if the GPS network had a frequency agility mode.

Second defence is to not use fixed frequencies at all, and to frequency hop. GSM phones have the capability to do this at 217Hz. Thus the effect of a jammed/interfered-with channel is averaged over the other time slices, and is negligible. Forward error correction is also applied, in order to be able to reconstruct the lost data.

Better still is to use a CDMA system, where the transmit bandwidth is so wide, and the amplitude so low, that the signal appears as noise to the adjacent channels.

Failing that, MLRS does a good job of anti-jamming.

[themightyimp]

@Roadster280

I think you will find that GPS has neither the ability to change frequency nor to frequency hop.

The techniques you mention can mitigate jamming issues but not in this instance :=

[Roadster280]

TMI - I'm not GPS expert, but it would surprise me if a military system had no ECCM capability by design. Perhaps it's not in the public domain, even if it did.

The other thought I had is in response to the question, why the enemy would want to jam it at all, since it would be useful to them too. Why not introduce a widely variable (10s of km) error, but have the error factor known to own forces? Nice bit of disinformation warfare. Much more sophisticated than jamming.

I believe we retired our (ground) jammers, because they were as useful as a 10MT nuclear warhead on the tactical battlefield.

[Pontius Navigator]

Roadster may I refer you to the GPS used by the crew on the HMS Cornwall Lynx. This is identical to the one I bought on eBay and have in my drawer. The one in my office is made by the 'other' manufacturer, is in a fetchind shade of green, has a lot of numbers on it and is decorated with a stylish NATO logo. It is no different from a commercial product.

There are other comments that I might make but I believe I got that information from protected sources.

What you might deduce from what I said is that there are GPS and GPS.

Remember too that GPS is a proprietary name whose full name is Navstar GPS. It is the US owned Global Navigation Satellite System. This link gives some useful background and the bit on Selective Availability is relevant.

http://en.wikipedia.org/wiki/Global_Positioning_System

There is a rival Russian system, GLONASS, with about 14 funtioning satellites:

http://usinfo.state.gov/xarchives/display.html?p=washfile-english&y=2006&m=February&x=20060203125928lcnirellep0.5061609

There is then a possibility that the European system Galileo will become operational too.

http://www.military-geospatial-technology.com/article.cfm?DocID=1379

I believe the Chinese have bought in to Galileo.

With 3 available systems and multi-channel capable receivers an exo-atmospheric nuclear burst would provide a 100% ECM solution. For local GPS denial you would need a battery of jammers to cover each satellite frequency and system.

[Roadster280]

PN - Thanks. I believe you have corroborated what I was trying to say, without saying it.

HMS Cornwalls' GPS has had plenty of press, in any case!

I honestly know bugger all about GPS in practice, but I do know a thing or two about mil radio systems in general.

Q. Why would an exoatmospheric nuclear detonation cause global system outage? Surely only those birds within range would be toast, those on the dark side of the "extra sunshine" could survive, and (less any EMP effects) continue? As I said, I know bugger all about GPS, are there not enough birds?

[Pontius Navigator]

I believed the exoatmospherics affected propagation and was not intended as of itself to destroy anything. You are right that constellations in sight of the burst would be toast. However this link http://www.studycommittee.org/high-altitude-nuclear-tests.html it tells how satellites entering the burst area where also destroyed.

It is possible that improved techniques have been developed to harden the satellites. http://stinet.dtic.mil/oai/oai?&verb=getRecord&metadataPrefix=html&identifier=ADA254944

[ORAC]

The other thought I had is in response to the question, why the enemy would want to jam it at all Well, knowing we have GPS guided bombs, rockets n'all, I'd be tempted to jam it whenever we we were under attack, and sod anyone else who got screwed up.....

[Pontius Navigator]

ORAC there is also the potential for seduction. For instance what better way to get a couple of rigid raiders an an ipod?

[Roadster280]

ORAC - Quite true, but so do the (conventional) enemy. Hence my suggestion of surreptitiously spoofing the output.

[WE Branch Fanatic]

Are you forgetting the difference between P code and the C/A code (which use different frequencies)? The latter is freely available via the open market, which means anyone can build it into weapons - hence the possible need to jam. A low power transmitter feeding false data could totally corrupt systems using the C/A code. Of course you could just transmit noise, but since the GPS reciever extracts the signal from noise it may be hard to fool if the signal doesn't look right (it knows what the GPS signal looks like, and correlates this against the noise to extract the signal buried within it - so jamming it with white noise won't achieve much).

[Pontius Navigator]

WEBF, mm, that would explain why the RN, on such an important mission used a cheap commercial GPS?

[RODF3]

The other thought I had is in response to the question, why the enemy would want to jam it at all, since it would be useful to them too. Why not introduce a widely variable (10s of km) error, but have the error factor known to own forces? Nice bit of disinformation warfare. Much more sophisticated than jamming
Nice idea, but unless the error changed randomly, all you would have to do to counter is go to a known location and measure the difference.:)

[Wader2]

RODF3, very true and indeed we do that already. DCRE set up some datum marks using a DGPS. We then check the hand-held against the datum and apply corrections.

Interestingly the Garmin, as used in Iran, has the ability to set a datum height. This, as advertised, improved its accuracy. My earlier Magellan did not have that feature.