Waterproof Magnetic Case
The GPS tracking device receives no "out- side" help in determining its position.
The GPS Tracking device receives information from an outside source which typically includes satellite ephemeris information which allows the tracking of the device to obtain quicker fixes, and also allows the tracking device to obtain fixes in obscured environments.
The GPS tracking device can determine its position by triangulation of the cell-towers in the area. Works best in Suburban areas where there is sufficient number of towers to perform the triangulation.