Have cell phone? We will find you!!

[Tidy]

I was speaking to a friend of mine who gave me details on a system that is being installed in some 911 call centers across the country.

This system uses the GPS information that your cell phone receives to automatically transmit your location to a 911 call center in case of Emergency.

It scares me to think of what this technology could be used for. All modern phones have GPS capabilities built into them , which means if you own a modern phone you can be tracked.

Seems to me that the work around for this is to start hacking pone o/s's to disable the GPS functions.

Anyone heard of this or have any comments?



T

[canadateck]

If they know to track "your" Phone.I would guess they know who you are,and if you were doing somthing that you knew you shouldnt, then leave the phone at home.I kinda like the idea, but would like to see a law, that they would need a warrant, Unless you are lost or somthing...

[Tidy]

I agree with you about the law. What worries me is also what if it is not law enforcement who is watching you?

[seinman]

My phone has an option to turn off tracking... however, it says "even when turned off it can still be used by 911," and therefore the police. So what's the point of the off switch in the first place?! I'm not against having GPS in my phone (i'll turn the phone completely off if I feel the need to be completely anonymous), I just can't for the life of me figure out why it can be turned off even though it can't really be turned off.

[themichael]

They can find you anyway. Its called triangulation. The cell sites 'know' where you are so they can hand off the link when you change cells. Its built into the system.

Phones that don't have a GPS receiver will still be located using this method. I used to work in an engineering department. GPS was WAY too expensive back then to put in every phone. It ias easier and much cheaper to just ask the towers where you are, they already know. 4 towers can 'hear' you and decide which one is closer. Most towers cover 2-3 miles.

Ham radio ops, CBers, and bunny huggers use similar methods all the time. Can be fun.

Just like the phone company didn't/doesn't need 3 minutes to trace a call (you have an originating number and the receiving number - Ma Bell didn't want the police and Feds to abuse Bell's power), if you cell is on you can be tracked. Just on, no call. The phones talk to the towers all the time.

[junkmalle]

Leave your cell phone at home when you don't want to be tracked.

[lordsmurf]

I don't think this qualified as news (as related to video). Moving to off topic...

[Tommyknocker]

Even if all this technology is true, as it probably is, what's the diffeence? There are almost 300 million Americans, and you really think the government has the time or inclination to wonder where they all are? Unless you are a wanted criminal, I doubt it.

[mats.hogberg]

Very few cell phones have GPS - and if they do, it's spelled out in big letters as a feature you have to pay for! - but since the network knows what station (cell) you're connected to, it's easy to roughly tell where a non GPS phone is. Depending on cell size, I'd guess this has the resolution of a square mile, not the GPS resolution of <10 meters...

/Mats

[bugster]

Without GPS, and if the user is in an are where several cells overlap, and if the network operator has installed, the right equipment, they can locate you to within 100m or so. But thats a lot of if's.

If you were only within a single cell, the best they can do is calculate your distance from the cell tower. As a cell can be up to 35Km (about 20 miles) (using GSM or PCS1900 technology), thats a pretty big area. 3G technolgies are limited to smaller cells of abot 5km (3 miles) and so can be more accurate, but still need multiple cell coverage to get to the 100m accuracy mark.

I believe it has been written into US law, or maybe just Telecomms regulations, that network operators must the capability of locating any mobile phone making a 911 call.

[Tool Man]

There is a system like that here in the UK. Anyone can use it for a fee, not sure how much. But a text message is sent to the person being tracked to ask permission
Sort of defeats the point really.

It uses the CELL that the person is using, and the signal strength to 'estimate' a location.

http://www.followus.co.uk/index.html

[Guest]

I have a locatiing feature on mine that I can disable.I leave it on. Shit if I get in trouble,I want people to know where I am.As far as neferious uses by the government, if the NSA want to listen to your phone calls ,it will. So why not have it on,unless of course you have tinfoil covering your head right now.

[Josef K]

I just found something related:

You Americans would have your privacy back in the event of a major terrorist attack.

Heh!

[Tommyknocker]

We americans? What do you the "G" means in GPS?

[Guest]

We americans? What do you the "G" means in GPS?

Indeed,but it looks like it can be jammed regionally.

[Josef K]

We americans?

Well I did kinda mean Americans as in Americans who are reading this - all others can just laugh at the chimp.

[Tidy]

Very few cell phones have GPS - and if they do, it's spelled out in big letters as a feature you have to pay for! - but since the network knows what station (cell) you're connected to, it's easy to roughly tell where a non GPS phone is. Depending on cell size, I'd guess this has the resolution of a square mile, not the GPS resolution of <10 meters...

/Mats

I have a friend who has been in the wireless phone industry for a long time in R&D and they told me EVERY phone made in the last 3 or 4 years has GPS capabilities.

[tweedledee]

If you were really worried about being tracked, wouldn't you buy a phone that can't be traced to you, use a prepaid sim card that can't be traced to you, and see a shrink about your paranoia.

[bugster]

Very few cell phones have GPS - and if they do, it's spelled out in big letters as a feature you have to pay for! - but since the network knows what station (cell) you're connected to, it's easy to roughly tell where a non GPS phone is. Depending on cell size, I'd guess this has the resolution of a square mile, not the GPS resolution of <10 meters...

/Mats

I have a friend who has been in the wireless phone industry for a long time in R&D and they told me EVERY phone made in the last 3 or 4 years has GPS capabilities.

Your friend is wrong/misled/bullshitting/dumbing down (take your pick).

See my earlier post re locating a cell phone. That is not GPS

BTW, just in case you want my credentials, I have worked in cellphone R&D for the last 17 years.

[BJ_M]

hehehe - it tracks by triangulation, right bugster? ...


same principle that has been used for 1000's of years ..

[bugster]

hehehe - it tracks by triangulation, right bugster? ...


same principle that has been used for 1000's of years ..

Correct, but it is no where near as accurate as GPS

[BJ_M]

of course -- a real GPS uses a different system of sat. based triangulation with 2 or more sats.

they do sell a phone here with a real gps built in ... not for tracking the phone fo course , but just as use as a gps .

[Tommyknocker]

of course -- a real GPS uses a different system of sat. based triangulation with 2 or more sats.

they do sell a phone here with a real gps built in ... not for tracking the phone fo course , but just as use as a gps .

Actually, my guys and I have worked GPS on F-16s since since when it first spun up. I remember having to carry a cheat sheet around with the windows when we had a satellite window over us. So I know for a fact GPS can operate with only one satellite, although the system will be degaded will be degraded.

[BJ_M]

i think most consumer gps needs two ? maybe with one it puts you in the middle of the lake instead of back at camp

[Tommyknocker]

You're right, as usual. Consumer GPS is degraded, my system was military standard.

[vitualis]

If there is only one satellite (i.e., the GPS receiver can only receive the signal from one satellite), it is impossible to get a lock. Think about it... all you know is the distance from the GPS unit to the satellite. That is, you could be in an infinite number of points as a sphere around the satellite. Even making the assumption that you are either not in the air and not underground (assumptions which may be wrong), your location would still be anywhere on a circle on the surface of the Earth.

If there are two satellites, your location would be in the intersection of those two spheres, which would be a large circle, whose surface would be perpendicular to the line joining the two satellites. Again, you cannot get a fix. Again, assuming you are not in the air or underground (dangerous assumptions considering the surface of the Earth is not flat so there will always be some elevation or depression in height), you could be on two points on the surface of the Earth.

You can only accurately start making accurate 3-D position with a minimum of 3 satellites. The intersection of the three sphere will yield two points. One will be high in space so you can probably assume that you're not there.

It requires a minimum of 4 satellites to give a single unambiguous position in 3 dimensional space.

Additional satellites work to give more data... i.e., reduce the amount of error in calculating the position.

GPS satellites give out two signals. A military one (which I assume is encrypted) and a consumer one. The military one has higher precision so you can get a more accurate calculation of position. In addition, it means you can optionally degrade the consumer signal (or even turn it off) without affecting the military one.

However, high quality consumer units now calculate the position from multiple satellites (don't remember how many, but from ? up to 20) and as such can actually achieve HIGHER precision than military units (or at least, the miliatry units they tell us about... ). In Gulf War I, the US Army (according to the popular press at least) was using consumer grade GPS units.

Regards.

[Tommyknocker]

Actually, since the satellite knows where it is, what time it sends its signal, and the receiver knows where the satellite is, and what time it received the signal, and the angle it was at when it received the signal. A little geometry was all that was need to get a good fix. Remember, you're talking about a system I maintain as part of my job. I know how many satellites I need for a lock, and what a receviever can do with one satellite locked on.

[BJ_M]

he forgot about the time signal -

[vitualis]

Not to be disdainful, I also know physics and maths.

It is impossible to get an umambiguous calculation with only one satellite. In fact, it is only possible to get a single location with a minimum of 4 satellites (well, with assumptions of non-space travel, 3).

It would be able to calculate a semiaccurate position from one satellite if your receiver also had an altimeter (and/or it could measure the incidence of the input signal --> which would require a GPS receiver to be in a fixed orientation each time you take a measurement, which I assume you don't and not to mention a complex antenna array) and a compass.

Even assuming the above, altimeters, compasses, or measuring the incidence of radio signals are highly inaccurate measures and so using these figures in a calculation of position would only give you a rought (very rough) location on the Earth.

The only accurate measure in all the above would be the time signal from the GPS satellites and of course, the pre-known position from those satellites. Thus, if you are talking about calculating positions commonly associated with GPS (i.e., metres to tens of metres), the only numbers that can come into the calculation must be data from the GPS satellites themselves --> and thus, you must have at least 4 (or 3 with non-space travel assumption) to get an accurate location on Earth.

Regards.

[Tommyknocker]

Yes, the fighter aircraft had all these systems installed as basic equipment, and only needed latitude and longitude updates from a single satellite. As far as altimeter, attitude, and so on, it already carries these systems on board. Trust me, I work on the system, I know what it can do.