Windows® Phone 8 Unleashed

A-GPS

Assisted Global Positioning System (A-GPS) is a satellite-based positioning system, which is generally the most accurate of the geo location methods available on the phone. The accuracy afforded by A-GPS, however, comes with a power penalty. It uses significantly more power than the other two sensing technologies. Because of this, it should be used only when an application needs a high level of accuracy.

GPS uses radio signals from satellites and does not perform as well in dense urban areas. In poor signal conditions, signals may suffer multipath errors; signals bounce off buildings or are weakened by passing through tree cover. Later in the chapter, you see how to reduce the effect of multipath errors by applying a movement threshold ...