How accurate can a GPS in a mobile phone?

Dr.sunil V July 28, 2014
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What is best precision in meters of GPS technology used in mobile phones? Taking into account combination of all parameters of GPS, WiFi and cell tower triangulation, what accuracy and precision radius does GPS provide for mobile phone users? For example, if a person moves from one shop to another shop nearby, is the GPS in an android phone capable of indicating such a move?

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  1. Hovsep A
    July 28, 2014 at 11:26 am

    the accuracy of a GPS device is dependent on the device chipset, If the GPS hardware can receive WAAS correction it can do better
    http://en.wikipedia.org/wiki/Wide_Area_Augmentation_System#Comparison%5Fof%5FAccuracy
    Assisted GPS can also help
    http://en.wikipedia.org/wiki/Assisted_GPS
    The GPS resolution depends more on the hardware than the software but the mobile phone is small so this will reflect on the GPS accuracy, you can get get 2 meters accuracy with some Android phones like like the Motorola Droid

    How accurate is Android GPS? Part 1: Understanding Location Data
    http://www.andygup.net/how-accurate-is-android-gps-part-1-understanding-location-data/

  2. Oron J
    July 28, 2014 at 8:10 am

    GPS in commercial phones has an accuracy of about 30m at best (military GPS is much more accurate than that). In combination with the other factors you mentioned, this goes down to perhaps 10m (it's difficult to find a precice figure since this is highly dependent on the situation on the ground). Howevedr, the accelerometers built into the phone can detect much smaller movements than that, so in my experience, even when the absolute accuracy is not that high, you can see movements of about 2-3m on the satnav app (such as someone moving from one shop to the next).

    • Dr.sunil V
      July 30, 2014 at 4:06 pm

      Thanks. I carefully read your reply , twice. Please tell , do accelerometers increase location pointing of GPS , or is it an independent technology like motion detection?

      2) Do current smart phones , like Android have accelerometers

    • Oron J
      July 31, 2014 at 7:42 am

      Accelerometers are a simple devices for of measuring acceleration in a particular direction. Essentially they are cheap substitutes for gyroscopes. See http://en.wikipedia.org/wiki/Accelerometer for details. Amongst other things, they can be used for inertial navigation systems (another common use are the "water level" apps on phones). Most smart phones have accelerometers built-in (at least, all the iOS, Windows Phone & Android phones I've seen do).

      Since they are not accurate enough to be used for a proper inertial navigation system, they are often used to supplement GPS. I'm not an expert on the subject, but my understanding is that the SatNav components lead the game, telling the phone where it is. A more precise fix is given using WiFi signals etc as we already discussed. As the phone moves, the accelerometers provide information on this local movement, which is often too small to be detected by the other methods anyway, and these changes are added to the location, until a new fix from satelites, WiFi and phone masts is obtained. This process is repeated regularly so that the system in effect autocorrects the cumulative errors and inaccuracies of any individual component.

      By the way, Satelite navigation systems are theoretically capable of being extremely accurate (down to 10-30cm for some systems, or even a few milimeters if all errors are corrected). The main limiting factors are the quality of the components in the receiver (a phone is limited in size & price) and the processing power that can be applied to the error correction (ditto). Military, industrial (e.g. mining) and large transport systems (ships) therefore tend to be much more accurate than phones, even though they use the same satelite signals.

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