How precise is GPS?

I remember someone said GPS could be as precise as 2 meters range which means even if I take a picture in a small office site with location services ON it is possible to trace down to the address of the office.

I tried to take a picture with my smartphone with location service, GPS is enabled. It then shows me a map, suggesting my location, which is precise, but not very precise, it suggests that I am in another building which is about 20 meter away from me. It also does not suggest the height of my location.

Conceptual Question
1. is it normal? Is it already the most precise GPS for most smartphones in the consumer market?
2. Or is it because my smartphone is a low-ended one so the GPS used is not a very precise one?
3. Next time I buy a smartphone how to know if the GPS used is a precise one

 

If you are inside a building, GPS either won't work or won't be very precise. It needs to "see" the satellites - the more of them the more precise the location.
GPS might have not been used at all though - it might have been a location service assisted by cellular data which is what is used when you are inside buildings and is less precise than GPS.

 

Hello

1. Does glass windows or wall affect GPS accuracy?
Yes I am in a building, but our windows are so big (but often closed), if I open the windows, will GPS accuracy improve a lot or change little?

2. How about WiFi? I often see the terms "crowded-sourced WiFi" when it comes to location detection with WiFi. Does it mean only WiFi provided by public venues like McDonalds or Starbucks or shopping malls will help to determine locations?

I am in a building where there should be no public WiFi hotspots nearby, however, as I turn on WiFi I can see a lot of nearby WiFi which are mostly encrypted and they are often individuals or flats. Could those WiFi help determine the location?


3. I think I've got a conceptual idea of how GPS and WiFi hotspots work to spot a location, GPS uses satellite while WiFi uses nearby geo-tagged hotspots,

But how about cellular connection?
I cannot understand how the data SIM card could detect the location of the devices

 

1. Glass does not affect accuracy of the GPS however GPS is the most accurate when it has the widest field of view so to speak. GPS calculates your position based on differences in time (arrival time) - if you have a view through the window than you only can receive signals from satellites that are in view meaning less satellites and less precision (this is oversimplified but you can google how GPS works if you want more precise answer)

2. No - if Wi-Fi SSIDs are used, it doesn't matter if these are public or not. As long as Google (or whoever) knows where a given SSID with a matching MAC address is it's enough. It doesn't matter if it's encrypted or not - all it matters is that they have a record that a router with a given MAC is somewhere.

3. Pretty much yes.

SIM card does not exactly detect your location but - it's just that you need cellular data connection enabled so that your phone could connect to google servers and check nearby SSIDs and MACs against their database of geo-tagged Wi-Fi networks - it's not stored locally.

That said there is one more way to approximate your location using SIM card alone. Your phone connects to BTS (base transceiver station) - this is your basic "cell" in cell-phone. Each BTS has its own unique number and list of those are public information in many countries. So it's easy enough to create a database of all BTSs with their locations. Since your phone logs into a BTS (one at a time even though it can "see" neighboring ones as well) there is a way to establish roughly where you are without access to GPS, cellular data or Wi-Fi.

 

A 20m mismatch from a satellite fix is completely normal, especially when you're indoors.

When you walk around with location service on your phone collects data about the BTS as well. LTE stations can also broadcast their location. Knowing the location of a BTS can be used to approximate your location, while by calculating the differences of signal strength among different BTSes the precision can be greatly improved. (This is often incorrectly referred to as triangulation for some reason.)

Glass as a material has practically no effect on GNSS/GPS. However some window glass panels have metal wires inside them or metal coating on the surface.

 

To Downloads and Mr.Koala,

OK, as I disabled the location service in the privacy setting of my Android devices, does it "suppose" to be that my location details would not be collected and analyzed by any installed apps by any means discussed above?

Is it usual or unusual that an apps still overrides the setting for location and collect my location information for their use of any kinds?

In that case, is it an illegal apps?

Anything I can do, to stop, or at least reduce the likelihood, for a particular app to collect my location details?

I have a real need to install a certain apps but I have a belief that it will collect my location which is something I do not want and will spend time to learn to avoid.

 

As of the current Nougat build, there's no function in Android API that allows an app to override location service settings without user interaction. Unless you give the app root permission you're in control.

In practice this has limited effectiveness since the app will still know your IP, which for many purposes is good enough. If you really need to hide, use a VPN.


Please consolidate similar questions into one thread.

 

When location service is disabled, could the apps still know my IP?

Even if an apps knows my IP, it shouldn't necessarily know my precise location right?

 

Yes, simply put, your ISP (be it for a cell, computer, etc.) will give you an IP and that IP address will be known to anything on the Internet you try to communicate to. The only way to bypass this is by VPN, the VPN's IP will be seen, not your actual IP address. Note that the precision on the location of an IP address can vary, but they'll get a general idea of where you are and which ISP you are using.

My current IP address, the one used for this post, would tell you exactly where I am studying at the moment for example.

 

Does iPad mini 2 (WiFi only version) have GPS? If it doesn't , how come the location tagged with the photo taken with the camera is so precise (100m error from my residential building where there is no any shopping malls nearby) Even the only McDonald here is quite far away from me. Could WiFi alone give such a precise coordinates of location?

Another question is, could WiFi , GPS or cellular data detect the height of your location? On the map I see with my iPad and Android devices it only shows the horizontal map, will I be able to know the height of the location detected ?

 

iPad mini 2 Wi-Fi only does not have a GPS however as you have been told previously Wi-Fi networks can be used to approximate you position regardless of if these are accessible to you or not. By referring to shopping malls or McDonalds you seem to assume that your iPad would have needed an open connection but it wouldn't.
If you were at home and you were connected to the Internet at the time (even if the location of your own WiFi hasn't been tagged previously) your iPad would have been able to approximate your location by using SSIDs and MACs of routers and networks nearby and checking them against Apple database.

As for the second question - GPS could and Wi-Fi/cellular could not detect your height off the ground.

 

Hi thank you for the very useful information for me and the future visitors.

Yes, I already know that we do not need open connection to WiFi of our nearby McDonald or public spots. However, as I said, there is NO McDonald or shopping malls nearby and NO GPS for my iPad, but I am surprised that how the location detected is so close (less than 100meters )

1. Did you mean any residential and private WiFi with SSID (not necessarily public sites) is already enough to approximate your location?

2. Neglect hacking issue or any illegal activities that involves high level of police investigation. If I turned OFF the location services for a particular app, does it mean, legally speaking, the Apple or Android developer has done enough security considerations or keep doing security fixes to avoid the apps trying to obtain any location information from me?

Once to emphasize again, considering only the apps alone because I don't fully trust the apps but it's very important to me , I cannot throw it away

 

1. Any Wi-Fi is enough. No one knows if a W-Fi is public or private by the way, it is just there so it gets tagged.

2. Probably yes.

 

Hello

1. If there is no any routers nearby or personal hotspots ,does it mean that location service by WiFi does not work?

2. Can I (and how to) disable my mobile device from checking for nearby WiFi so that my location will not be approximated by WiFi?

In that case, how can I connect to my WiFi egg?

3. The same question to Q.2 , but how to do it to laptop, running on windows 10?

 

1. Location by Wi-Fi would not work in a situation like that but devices that have 3G/LTE modem or (obviously) GPS module could still get an approximate (LTE/3G) or exact (GPS) fix.

2. I think you already did that on your Android device judging by your description of what you did (although I'm not sure if you've described that in this thread or in another one). And you will be able to still use WiFi

3. No idea. I don't use Win 10 on any of my notebooks, sorry.

 

For point 1, yes but I have disabled GPS

For point 2
Did you mean disabling location service to particular app while WiFi is ON . Then WiFi will not approximate the location by the nearby spots?

 

Indeed, and that should solve the issue/

One thing is you should not allow location privileges to the application in question. Secondly I would not allow Android to use A-GPS at all (assisted GPS meaning it uses Wi-Fi hotstpots and other means to speed up getting a fix on your location)

 

Normally speaking if I have disabled the privilege to a particular application to know my location, does it mean it's good enough to hide my location to the apps? I heard somebody on Android forum saying that the apps could still override the privilege if it has the privilege to change the system setting, so I have to make sure it's not authorized to change the system setting. However, I have hard time finding out how to disable the privilege of a particular app to change the system setting. Any ideas??

Is Assisted GPS actually a collective term of detecting your location by other means rather than GPS, or is it another piece of hardware chip inside the phone that is not GPS but something less superior so it's called assisted GPS?

 

AGPS is the wifi based method we've explained to you several times in this thread.


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