GSOF message: Position Sigma

This message describes the Position Sigma information. It contains the following data:

• Position RMS

• Sigma east, in meters

• Sigma north, in meters

• Sigma up, in meters

• Covariance east-north

• Error Ellipse Semi-major axis, in meters

• Error Ellipse Semi-minor axis, in meters

• Orientation of Semi-major axis in degrees from True North

• Unit variance

• Number of epochs

Sigma (Type 12 record)

Field	Item	Type	Value	Meaning
0	Output record type	Char	0Ch	Position sigma information output record
1	Record length	Char	26h	Bytes in record
2 to 5	Position RMS	Float		Root mean square of position error calculated for over-determined positions
6 to 9	Sigma east	Float	meters
10 to 13	Sigma north	Float	meters
14 to 17	Covar. east-north	Float	number	Covariance east-north (dimensionless)
18 to 21	Sigma up	Float	meters
22 to 25	Semi-major axis	Float	meters	Semi-major axis of error ellipse
26 to 29	Semi-minor axis	Float	meters	Semi-minor axis of error ellipse
30 to 33	Orientation	Float	degrees	Orientation of semi-minor axis, clockwise from True North
34 to 37	Unit variance	Float		Valid only for over-determined solutions. Unit variance should approach 1.0 value. A value of less than 1.0 indicates that apriori variances are too pessimistic.
38 to 39	Number of epochs	Short	count	Number of measurement epochs used to compute the position. Could be greater than 1 for positions subjected to static constraint. Always 1 for kinematic.