GPS Jamming

[Godot]

Hansard January 2002


Norman Baker: To ask the Secretary of State for Foreign and Commonwealth Affairs what his policy is in respect of the monitoring by GCHQ of communications originating and terminating within the UK. [28635]

Mr. Straw: GCHQ may monitor communications originating and terminating within the UK only in accordance with law, and in particular with the Regulation of Investigatory Powers Act (RIPA) 2000.

Norman Baker: To ask the Secretary of State for Foreign and Commonwealth Affairs if he will make a statement on the purpose of Morwenstow station: and how many (a) US and (b) UK personnel are based there. [28584]


Mr. Straw: GCHQ Bude, previously known as the Composite Signals Organisation Station at Morwenstow, employs approximately 200 people and provides intelligence support serving the interest of the UK and its allies. It is long standing policy not to provide details about the operations carried out at Bude or to provide a detailed breakdown of staffing.

 

[Godot]

Now the area has been given extra protection (!) as of June 1st 2007. Only 1 of 16 to be given this status

http://www.knowledgenetwork.gov.uk/...368a8297ae46a2c3802572e20042ca09?OpenDocument

 

[Diesel Benz]

Easy. The signal strength you pick up from the satellites is tiny, so they just need to transmit a locally stronger jamming signal on the same frequencies.

Since the affected area is/was relatively small, it cannot be the selective availability approach. Since it was for a short time (and local), it cannot be a satellite orbit change. The above must be the real explanation. Once they only jam the frequency band used by GPS, no other services are affected.

The main affected area must have been even smaller but since useful as well as (intentionally or not) harmful radio signals propagate to a varying distance, they must inform a "safe margin" for the affected area.

Yes, this would have been a good opportunity to test the MB Navi performance without GPS support, one should be able to pick up the correct road even after a reasonable driving distance without GPS. The error of course gets larger with time but as long as one does not expect an accuracy of a few metres and not driving in a complex city centre, the navi should be pretty usable.

 

[glojo]

but as long as one does not expect an accuracy of a few metres and not driving in a complex city centre, the navi should be pretty usable.

We're talking Cornwall here. A land where foilks think the central reservation is the grass growing in the middle of a country lane. You ask Jethro

I can't help but wonder if we will just see intermittant breakages in the signal?


John

 

[GrahamC230K]

I have used a GPS system (not Comand) without a GPS signal, relying only on the gyro and speed input.

I am not sure how Comand works, whether even when you are not using the navigation, say just listening to the radio or even the unit "off" if it tracks your position.

If it does fine I expect it to make a reasonable job of navigating, if not, gyro and speed input is useless if it doesn't know whewre you are to start off with.

As this is Glojo's thread, I am NOT saying Comand works like this, I am NOT saying it does. I have NO idea how Comand works. I HATE people that waffle.

 

[Alfie]

I have used a GPS system (not Comand) without a GPS signal, relying only on the gyro and speed input.

I am not sure how Comand works, whether even when you are not using the navigation, say just listening to the radio or even the unit "off" if it tracks your position.

If it does fine I expect it to make a reasonable job of navigating, if not, gyro and speed input is useless if it doesn't know whewre you are to start off with.

As this is Glojo's thread, I am NOT saying Comand works like this, I am NOT saying it does. I have NO idea how Comand works. I HATE people that waffle.

COMAND does use speed input and gyro to navigate. I have used both COMAND 2 and COMAND APS to navigate with no satellites at all. The system is pretty clever in that so long as your starting position is known, then it will work reasonably well. Comand locks onto the nearest road which is fine until you come to a road which has another parallel, with traffic flowing the same way and close to it!

 

[JohnM]

I experienced some weeks of COMAND operating without GPS when my GPS antenna failed. After 3 weeks the car was quite sure it was in the North sea getting closer to Norway daily (having started out in Surrey).

 

[prprandall51]

I experienced some weeks of COMAND operating without GPS when my GPS antenna failed. After 3 weeks the car was quite sure it was in the North sea getting closer to Norway daily (having started out in Surrey).

Before the days of GPS, navigation systems had the facility to reset your position manually - which was necessary from time to time. Nowadays, if GPS were to go down for any length of time, we would all be up the creek by being without the manual resest facility.

I wouldn't be surprised if nav system manufacturers have rather come to rely on GPS rather than using it for the occasional position cross check. It's so easy to just look up the position using the satellites.

I had expected Comand to do a bit better than that, though!

Philip

 

[Satch]

It is a resilency test. The internet holds many things, including instructions on how to construct cheap DIY GPS jammers that amateurs with a certain amount of technical skill could build from easily available bits and bobs to jam the civilian GPS frequency.

So what you think, civil-use GPS signals broadcast at 1575.42 MHz and not the military frequency of 1227.6 MHz which s more robust anyway.

Ah, but many older generation military GPS receivers still in use must first acquire the civilian signal before locking onto the military signal and quite a lot of cheaper civilain GPS handsets are in general use anyway.

Take a squint at this and marvel at how "old" technology is being used as a backup:

http://blogs.govexec.com/techinsider/archives/2007/05/china_poses_threat_to_gps_but.html

 

[Flasheart]

I have used a GPS system (not Comand) without a GPS signal, relying only on the gyro and speed input.

In my day we called that Dead Reckoning. Using all available data, heading, distance travelled, input wind and bobs your uncle, ***** is your mothers sister and we are lost.... no i will have a fix in a minute hang on.....

Its fairly simple maths.