How is GPS/Location Accuracy of iPhone

[Dong-Min]

I was just wondering that how accurate is the iPhone GPS/Location and the WiFi location finder and do this work accordingly. If you can give some information about this then I will really appreciate your reply. I searched for this on google but not got proper information on this. I expect quick replies on this.

[Rhesa]

There are several sources of error in any GPS reading. Some of these errors are due to natural factors, and some error is presented in the literature about the Selective Availability (SA) that you can find on the internet. When the GPS uses these inputs to solve your position, it is only natural that your position will also be a mistake. If you study the equations that uses GPS to resolve its position, you can analyze what are the effects of these errors and you could find a formula and predict what would cause errors.

[Suigetsu]

While you sit and wonder where you are, watching your GPS, you note that the position it gives wanders around. Some of these positions should be accurate, but what is the right position? If you wait long enough, you can take the average of the data and find your location with an accuracy improved. From this you can calculate what the average deviation. The next time you use GPS, you would find that the GPS position change in a manner almost identical, so you could use your numbers "mean deviation" to estimate the accuracy of your new GPS. The only problem is that these numbers changes, so it is not easy to increase the accuracy. But the idea is good.

[Chopfyt]

The DOP factor is used for detecting the position. The DOP only depends on the position of the satellites: how many satellites are visible, how high they are in the sky, the angle of vision. This is often referred to geometry. The satellites are moving, and the geometry changes with time, but it is very predictable.

[FarhaS]

The DOP is often divided into components. These components are used because the accuracy of the GPS system varies. For example, the horizontal position can usually be measured more accurately than the vertical position. Input errors are identical, but the geometry may favor one direction over another. VDOP DOP is vertical. HDOP is the horizontal DOP. There are also PDOP for positions 3 Dimensions, TDOP for the time and GDOP for the geometry of DOP which is all the results together.

[Beatricef]

There are some ways by which you can improve the accuracy. Here are those ways:

• Using a differential GPS system to reduce entry errors.
• Improve the DOP using more satellites.
• Take your measurements when satellites are present above the sky.
• Average the GPS position readings over time.

[VazV]

That is not always 100 percent accurate but that will be within .5 kilometer range. But I think that this is enough to identify the location of somebody. For this, your device continually update the data and consumes your data uses also.