GPS Jamming over most of UK 7/8 JUL

[Aussie Andy]

Just spotted this in the NOTAMs:

AC 5555
07 JUL
1100-1400 30000ft (A1063/02pt)
08 JUL
0715-1015 30000ft (A1063/02pt)
GPS Jamming Activity 5555N 00550W rad 320nm. Tel 01436 674321 X
4402/4404/4379

So thats the whole of the UK almost as far as LHR!!!

We have been warned!

[AerBabe]

Is this common? Any idea why they would be jamming them?
Not that I use one, just curious :)

[distaff_beancounter]

Anyone know WHO is doing the jammimg & WHY ?

Where is noggin when we really need him ?

Ah well, I suppose this means that I will have to revert to a chart, & mark one eyeball, for a bit of navigation, this weekend. :D

[Aussie Andy]

I've only used a GPS on one previous trip (France/Spain) so not too worried. Anyway, my trip to Leicester and Wyton this weekend is on Saturday, weather permitting, so not affected.

As to who and why, well I'm pretty sure it would be the military testing their ability to deny the service to others whilst still operating effectively themselves - its a defence issue.

Yet another reason not to rely solely on GPS!

[WO]

Possibly MOD testing to see just how vunerable GPS is to jamming?
Remember, our cousins across the pond are considering using GPS as the primary air navigation tool as opposed to good old NBD's and VOR's.

Uncle Tony and his band of merry men might want to find out for themselves what could possibly go wrong if we tried it.

Or am I way off course? ( if you'll pardon the pun!)

WO

[A and C]

You are way out of date the US goverment is now not going for GPS as a the only navigation system because of the problems outlined above.

In fact funding for new NDB,s and replacment of old VOR equipment has been granted for the short term.

For the longer term I suspect that GA aircraft will be using dual DME to update the GPS position via the data ports that most panel mounted GPS units have.

[Go-Around]

This link shows the area affected.

http://gc.kls2.com/cgi-bin/gc?PATH=&RANGE=320nm@55+55N+005+50W%0D%0A&PATH-COLOR=red&PATH-UNITS=nm&SPEED-GROUND=&SPEED-UNITS=kts&RANGE-STYLE=best&RANGE-COLOR=navy&MAP-STYLE=

[FNG]

Call me cynical, but I suspect that some (not all) ppls who rely on GPS as their main or only system of navigation may also be none too diligent in checking notams. If so, and if they don't also visit this bulletin board, there could be a bit of oops going on this weekend.

[Aussie Andy]

Same thought occured to me mate! Hey, I know, maybe PPRUNE should be referenced in the AIP as a necessary element of pre-flight briefing ;-)

[StrateandLevel]

GPS was designed as an "unjamable" aid, it uses spread spectrum modulation and correlation techniques which make it very difficult to jam over a wide area. It requires some very clever techniques to effectively jam signals that are inherently below the ambient noise level; MOD want to find out just how susceptable it is and conduct periodic trials. Thats not to say they will be effective but you have been warned!

Interestingly it is illegal to "interfere with other wireless telegraphy" but as GPS does not operate in a frequency band allocated to radio navigation, it is considered as fair game.

[QNH 1013]

I do check the Notams before flight - I particularly don't want to get mixed up in PJEs. However, I would have missed this because it only appears in the Scottish A8 Fut notam. I would have thought something with a 320nm radius should also have been in the London A8 notam.
I have not been in the habit of looking at the Scottish notams when my flight is within the London FIR and I never thought I was doing anything wrong. What do other pilots do?
Fortunately I don't rely on gps. Thanks for bringing this to our attention on PPRUNE.

[N Reg Aztec]

Spoke to the people at the contact number provided in the NOTAM and the details are as follows:

28 nm range from 51 52N 5 40W from a four hour period in the range 0800-1700 local daily from 5/7 to 8/7

320 nm range from 57 35N to 4 00W for a one hour period in the time ranges:
1600 - 1900 UTC on 7/7
0715 - 1015 UTC on 8/7

320 nm range from 55 55N to 5 50W for a one hour period in the time ranges:
1100 - 1400 UTC on 7/7
0715 - 1015 UTC on 8/7

The purpose it to test mobile GPS jammers.

Looks like I'll have to use that thing with the dials and needles again.....
:rolleyes: :D

[Romeo Romeo]

I'd have missed it as well. I check the NOTAMS, but if I'm in going to be London FIR I only check the London NOTAMS. However I wonder how much it will affect us. GPS uses high frequency ratio wave (in the GHz, I believe) which are only 'line of sight', so if you're pottering around somewhere on the Southern map at 2500ft then my guess is that you won't be affected.

[propjockey]

I recognise the telephone number - its the AirOps Room in Faslane, Scotland, been well published in NOTAMS before.

GPS is jamable! Put enough nonsense into the receiver and close enough and its gonna stop working.

It uses freqs in the 1.5 and 1.2 GHz bands - yes NORMALLY line of sight use.

Don't forget radio range vs altitude means a larger coverage area. 320NM - dunno what that equates to ?

where does the lat/long put it?

Some where in the Clyde estuary would be my guess!

regards

[Evo7]

Lat/Long puts it on Jura. Apart from a distillery, I've no idea what's there. Good one for the UFO lot :)

[QDMQDMQDM]

For a really good way to pick up notams go to:

http://www.notamplot.flyer.co.uk

This is a program which basically downloads the notams and then displays them graphically on a map of the UK so you can see immediately which ones affect you.

Apologies if this is old hat.

QDM

[WorkingHard]

S&L
If what you say is correct then presumably the GPS is not covered by the RCA "licence" fee (for licence read RIP OFF). In which case we have no ability to challenge the RCA fees. HOWEVER when the military jam other frequencies for testing then the RCA may have allowed the breaking of the terms and conditions of your licence so could be challenged for the fee. Any experts out there care to enlighten us?

[Rattus]

JMC!
The jammer is just inside the entrance to Loch Ewe.
Please don't ask me how I know... I'd have to kill you. :D

PS The jammer is pointing out to sea, so only the Fleet should suffer. However, it would appear from the NOTAM that the effects of backscatter are an unknown quantity, so you'll just have to start navigating again. :p

[Aussie Andy]

QDMQDMQDM (great name btw!) - yes, Notamplot is excellent - thats how I spotted it. I strongly recommend Notamplot to everyone!

[StrateandLevel]

Working Hard

Quite right the aircraft radio licence does not cover the GPS. At one point the RA said they would sell GPS licences for £5 to make the use of GPS legal! Never head of anyone with one!

The radio licence fee covers administration and costs for "protection" of frequency space; believe it or not the RA actually do a good job here, if you see how many people they apprehend every year.

As regards to jamming other protected frequencies, it would be an offence however, the military can usually get away with such things in isolated areas.

Why doesn't everyone monitor their GPS and see if it really is affected on the notamed dates. Chances are you will not observe anything. If you do, respond here and we can see how effective the jamming is or isn't.

[propjockey]

Ah good old JMC!

great fun!

Its prob covering their backs - my past comms experience would bring me to think that think there would be little backscatter at GPS freqs but I bet they would want to make sure there was not blame if something did happen!

As GPS was orig a MIL system I don't think its protected in any way - someone may enighten us otherwise

[Aussie Andy]

I agree that its unlikely to affect us a long way away, say London area, unless at great height / line of sight - e.g. 30,000'

All that would required to block / jam GPS is a signal on a similar frequency capable of swamping the receiver front-end. Given the low signal strength at microwave frequencies involved in reception of signals from satellites, this isn't too hard in itself if you can put a jamming source close to the receiver you are trying to jam.

But its hard to imagine how you do this effectively over a very wide area? Maybe instead of relying on very strong blocking signals they are instead transmitting bogus, but similar, signals to confuse receivers and cause intentional errors?

But I have no idea whether this is what they do in practice and agree with previous post that the NOTAM is probably a "CMA" effort! I'd be very surprised if we notice it in practice. Still, we just don't know - and we'd better play safe and heed the NOTAM warning I suppose!

[englishal]

Dunno why they feel the need to jam GPS...its already possible to disable GPS in certain areas, while keeping it active elsewhere, and I'm sure if Tony was to have a word with his buddy George W, then they'd turn it off wherever we asked :)

The best GPS jammer I've seen is a GPS receiver with a dodgey antenna, causing it to re-radiate. Knocked out all GPS's within a 2 mile radius...(and took us f@@king days to find, as no one though a GPS 'receiver' could re-radiate)

Cheers
EA;)

[bcfc]

Anyone notice anything?

[Dan Winterland]

GPS is dead easy to jam - it's such a low power transmitter, any signal on the same frequency will mess with it. If the duration of the jamming signal is more than 25 seconds (the length of one complete cycle of the pseudo random code, a receiver will have great problems working out it's postion. The Russians have developed a GPS jammer, and it's commercially available :eek: You can bet the Serbians had a few during the Kosovo war!

Also bear in mind that it's Uncle Sam's toy and he can do with it what he pleases. Although SA (Selective Availability - the system where accuracy is downgraded) is currently switched off, it can be switched on again at any time and the level of downgrading increased - even locally. The only way to avoid this SA is to have a receiver that picks up the military GPS frequencies and have the current encryption de-codes. A civilian aint going to get those!

[Min Sink]

The other way to get around SA is to use a differential GPS receiver. This receives another signal from a ground station also with a GPS receiver. The ground station knows exactly where it is it can work out the SA error. This is then transmitted to your differential GPS giving a very accurate position.

[StrateandLevel]

One problem , if your GPS receiver is jammed, the differential GPS receiver which must be in close proximuity will also be jammed.

Each GPS transmitter is on average 16 times more powerful than a Satellite TV transmitter and spread over a wide frequency spectrum. To jam it for even 25 seconds, over a mediocre range, will require an enormous ammount of RF energy bearing in mind the bandwidth and that the RF field reduces in accordance with the inverse square law.

[DeepC]

The error signal from DGPS could be on a totally seperate frequency from the GPS signal and it could be spread over any number of frequencies. Bit difficult to jam. I work in engineering where the industry uses DGPS regularly for survey work. Very accurate. Ordnance Survey operate an 'active network' of error transmitters.

All that said, the fixed station has to be reasonably close, within a couple of miles, to reduce the errors by enough.

[StrateandLevel]

But its not the error signal that would be jammed, its the GPS input to the reference receiver which is likely to be in close proximity to the working receiver (2 miles you state). If one goes the other goes and the reference signal won't exist.

DGPS only takes out propogation and position errors it doesn't increase immunity to jamming.

[Danza]

As bcfc said "did anyone notice anything?", although I haven't got a GPS yet :( still saving the money for it.

[Rattus]

bcfc

No, I didn't notice anything this time, but I am a bit distant from the action.

DGPS is not the answer, as a number of correspondents have already pointed out. If the diff station is receiving corrupt data from the satellites, it will only compound the error.

GPS jamming is however good for the ego - I once got an indicated 630 kts :cool: out of a Diesel Astra on the Quiraing road between Staffin and Uig.

The JMC finished last night - as soon as we can be sure the Septics :p are out of Scottish waters, it'll be safe to come out...

http://news.bbc.co.uk/hi/english/uk/scotland/newsid_2122000/2122687.stm

Happy days!

Rattus

[Evo7]

On Tuesday a British frigate fired a shell into a loch eight miles off target and just one mile from the village of Durness.


I guess it's an improvement over shouting BANG, but I'm not impressed.... :)

[skua]

I flew from London to Yorkshire on the 7th, having picked up the notam from notamplot. (Endorse AA's comments about how useful it is - why did AAIS not launch the product themselves?)

Did not notice a thing. But a good job that there was reasonable VMC throughout. The cu's over Lincolnshire provided one of those aerial playgrounds that come along rarely....

Skua