On those new RAC TV adverts it says they can locate your breakdown using your mobile phone. How do they do this? Is this only if your on certain networks? How come just the RAC do this and not the AA?
- posted
18 years ago
On those new RAC TV adverts it says they can locate your breakdown using your mobile phone. How do they do this? Is this only if your on certain networks? How come just the RAC do this and not the AA?
Any mobile can be traced by anyone, provided the owner has agreed to it. it is just a selling point for the rac
mrcheerful
I think it is done by using three mobile phone masts. They test the signal strength from each mast, and then they can predict roughly where you are between them. I think it's accurate to within a few meters.
probably not even that. How do they know whats blocking the signal? Could be a row of buildings on one side, and empty fields on the other.
... or even if they haven't agreed to it, for some agencies. A certain Serb was lucky to avoid being blown up a while back when a missile was dispatched to where it was thought he was (on the 'phone). As far as I know, the location is done by triangulation. Location is likely to be more useful in rural locations than urban, seemingly.
AFAIK they use signal timings not strength to triangulate, so should be effected too badly by the environment.
CPS who were one of the original innovators of the idea suggest their basic product has an accuracy of 300m-3km (depending on number of cells within range etc.). Newest product improved to around 250m, although I'd expect better in the heart of a city with plenty of masts within hailing distance:
IMHO completely useless if you are on a B road in the middle of the countryside, but makes for nice marketing gumph.
I often see triangulation of mobiles being quoted as miraculously accurate even by the mainstream press. Is this a Hollywood invention?
The message from "Joe" contains these words:
Yeah, but by the time they're that close they can hear the pinking.
Multipath distortion, innit? But unless the location arithmetic has improved a lot from the accuracy achievable when I last looked, that would have to have been quite a large missile.
In the latest Orange cinema ad (Daryl Hannah's) our hero claims, through clenched teeth, that someone could be located `if they had GPRS on their phone'. Does that make sense? Does it help? If so, how?
The message from snipped-for-privacy@ssrl.org.uk (Sam Nelson) contains these words:
There is impending legislation in the US to make all new mobiles be intentionally radiolocatable. It may even be here now. IIRC it includes a stand-by mode instead of turning off so that it can be woken up by a suitable signal. Obviously this takes a lot less battery power than the phone itself transimitting its position all the time to cellmasts - it just waits till interrogated then talks at full power for as long as it can.
It can be very accurate if the phone is asked by the network to report sinal strengths back to the network.
Clearly the network knows approximately where the phone is by which cell/sub-cell/sector the phone is in, and what other cells can 'see' it, but if the network then asks the phone which cells it can 'see' including other-network cells, then an accuracy of better than 50m is achievable.
Provided the precise location of the cells is known...
Think of AGPS as provided by Three.
petermcmillan snipped-for-privacy@yahoo.com reckoned that...
It's nowt to do with signal strength, it's a parameter called "timing advance" which is measured. Accuracy is reasonable but improves in line with the number of transmitters covering the point being calculated. The technique is called "cell site analysis" and was most recently/infamously used to help convict Ian Huntley.
In message , Jon writes
However in this instance the police were very lucky. I believe the evidence was limited to which cell Jessica's phone signed off to rather than a measurement of timing advance etc. By some fluke Jessica's phone used the Burwell transmitter rather than Soham's, and combining that information with the known route the girls took, they were able to identify accurately which areas had a "blind spot" to the Soham transmitter. Details and a better explanation here:
I remember software for the Nokia 6600 which would tell you where you were in the world, and change profile depending on whether you were. Useful :)
Do you mean metres..? I don't have 100 meters on my car dash ;-)
Ivor
Did you mean GPS..? Many American mobiles now have GPS (satellite nav) circuitry built in, apparently it's a requirement for 911 (emergency) calls or something.
Ivor
No, the advert is referring to the 'Find where you are' service on Orange World. Just an advert for an Orange service I'm afraid Ivor!
Tariq
Yup, radio triangulation - hardly a new concept - are they only just starting to utilise this to some decent sort of advantage?
It's done off the timing, not the signal strength
On a good day if you're lucky
Their positions very well known
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