Difference between revisions of "GPS accuracy"

Revision as of 11:40, 5 June 2008

Basic Calculation:

E-W accuracy = (10^-2) * Width of graticule in feet
N-S accuracy = (10^-2) * "Height" of graticule in feet

This means you can get within a circle of radius Sqrt(AccuracyEW * AccuracyNS / pi) feet of your target coordinates.

Example Error Calculation

For a "normally-sized graticule" (taking the Cincinnati Graticule, 39 -84, as our example), a GPS receiver of the following accuracy results in possible errors of:

Cincinnati Graticule's size :

E-W (across the 39.5 latitude line): 53.46 miles * 5280 ft/mi = 282268.8 ft
N-S: 69 miles * 5280 ft/mi = 364320 ft

3 decimal places

E-W accuracy: (10^-2) * 282268.8 ft = 282.2 ft
N-S accuracy: (10^-2) * 364320 ft = 364.3 ft

This means you can get within a circle of radius 180.8 feet of your target coordinates.

More sensitive receivers

# Decimal Points	Radius (Ft)	Radius (m)
2	1809 feet	551 m
3	180.9 feet	55.1 m
4	18.9 feet	5.51 m
5	1.809 feet	55.1 cm
6	0.1809 Ft (2.17")	0.0551 m (5.51 cm)

@@ Line 47: / Line 47: @@
 | 6
 | 0.1809 Ft (2.17")
-| 0.55 m (5.51 cm)
+| 0.0551 m (5.51 cm)
 |}