GPS accuracy is very hard to predict. The GPS receiver in the M7 GX has these specifications:
” Horizontal <3 meters (50%), <8 meters (90%)
” Altitude <10 meters (50%), <16 meters (90%)
” Velocity 0.06 m/sec
Tests show that the unit-to-unit position difference when two M7 GXs are very near each other is typically within +/- 0.00001 degrees (1.6meters).
In typical GPS operation, four or more satellites must be visible to obtain an accurate result. Four sphere surfaces typically do not intersect. Because of this, it can be said with confidence that when the navigation equations are solved to find an intersection, this solution gives the position of the receiver along with the difference between the time kept by the receiver’s on-board clock and the true time-of-day, thereby eliminating the need for a very large, expensive, and power hungry clock. The very accurately computed time is used only for display or not at all in many GPS applications, which use only the location.