Typical time and horizontalAccuracy of iPhone CLLocation in practice

Question

I'm wondering if anybody has done thorough empirical testing of the iPhone's ability to find its location. Obviously the performance and accuracy will depend on the type of area one is in (urban vs suburban vs remote).

Just testing from the Simulator, I get a horizontalAccuracy of < 100 meters (98 meters) in a few seconds. I believe it is because it's using WiFi.

But, for user experience purposes, how fast would it be to get this kind of accuracy using EDGE or GPS (assuming both are available)? Does the timing vary in very dense urban areas vs suburban?

It would be great it there were some empirical results published on this so that apps could modify their user experience accordingly.

Answer 1

There is a difference in accuracy between models of iPhone, whether "real" GPS, or wifi triangulation, or cell tower location are being used, as well as issues from sky coverage and the particular satellites in view when GPS is being used, as well as how long you wait.

In practice, the range I've seen is from infinite (or maybe the diameter of the planet) when I'm in an elevator (Faraday cage), to telling me when I walk from the front to the back of my car.

Answer 2

The simulator just sends one event with the coordinates of Apple's headquarters after a few minutes delay.