Current accuracy to pinpoint 3G-signal?

Apart from the use of Tor to surf anonymously, what is the current accuracy for investigators to pinpoint a 3G USB-modem connected to a laptop in a populated area? The laptop has no GPS/Bluetooth/IR or other any other communication device. Some say it's possible to be pyshically pinpointed with an accuracy of 150 meters, some say 50 meters but what is the current accuracy? I know they pinpoint by calculating the distances between the modem and the celltowers, but is it possible for them to pinpoint you with an accuracy of 10 meters or less? I know that pinpointing a GPS device is with an accuracy of 1 meter, but how is that in the case of a laptop with a 3G USB-modem?

I want to know this because I want to use an anonymous and prepaid 3G connection for using Tor and not want to be marked as a Tor-user. They are recording and registering everything these days so if they can pinpoint the location of a 3G-modem with an accuracy of 10 meter then they record the coordinates of my appartment and they know there lives a Tor-user. In that case I have to use 3G --> VPN --> Tor. But imagine that if the accuracy would be around 100 meters, in that case it's more difficult for them to locate he Tor-user exactly (in an area of 100 meters live around 300 people).

Any knowledge/suggestions/brainstorms on this issue would be very appreciated.

 

There is no simple answer to this question. You have to weigh the severity of your crime and the agency involved to gauge their capabilities.

Local Law Enforcement:
Prank 911 Calls usually can be tracked within a block or two of the location on mobile devices.

Three Letter Agencies:
- remote access attempts
- devices like sting ray (mock cell towers) could be used to set trap.

Beyond that, I don't really think you could put down an answer to the range or the response time. Standard police have caught simply because they had an officer in the area, but that's a matter of luck. Chris Dornor shows they can throw a bigger net down to catch people if they needed to. Not to mention all the variables you can't control: public surveillance, witnesses, etc. So if they don't catch you in the act, then they might afterwards based on video footage. It's hard to evaluate the effectiveness of that setup without knowing your intentions.

 

Not sure where you get your info on accuracy of geo-location but would like to hear it!
I have a pre-paid mobile broadband connection and all my research into this aspect indicates that there is no such thing as accuracy – more like conjecture. Unless your device (PC, etc) is GPS enabled – I don't see how to pinpoint a 3G modem with any kind of accuracy. A 3G modem is a simple device with some software and drivers installed – not to be confused with a mobile phone!

Where have you seen information stating that the distance between a 3G modem and the cell tower can be calculated?
You really would need 'line of sight' (laser technology) to do this. Not very practical in an urban environment. Then there are other considerations such as strength of signal (or lack of) – demand on the network, atmospheric conditions, etc, which make a mockery of trying to measure distance from a mobile tower to your modem.

Another complication is the 'mobile' factor – what if you take your computer to another location?
When you fire up your computer you get a new IP – plus you're in a completely different position – where would that leave any hyperthetical snooping agency?

I think your 3G modem would be the least of your geo-location concerns – you have more to worry about regarding programs already installed on your system. Eg, browsers, whether you use Google maps, etc - and whether you have already told people (read Facebook, etc) where you live!