User's Manual

B GSOF Messages
138 SPSx50 Modular GPS Receiver User Guide
• Orientation of Semi-major axis in degrees from True North
• Unit variance
• Number of epochs
SV Brief
This message provides brief satellite information. It contains the following data:
• Number of satellites tracked
• The PRN number of each satellite
• Flags indicating satellite status
Table B.8 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
2-5 Position RMS Float Root means square of position error calculated for
overdetermined positions
6-9 Sigma east Float Meters
10-13 Sigma north Float Meters
14-17 Covar. east-north Float number Covariance east-north (dimensionless)
18-21 Sigma up Float Meters
22-25 Semi-major axis Float Meters Semi-major axis of error ellipse
26-29 Semi-minor axis Float Meters Semi-minor axis of error ellipse
30-33 Orientation Float degrees Orientation of semi-minor axis, clockwise from true
north
34-37 Unit variance Float Valid only for over-determined solutions. Unit variance
should approach 1.o value. A value of less than 1.0
indicates that apriori variances are too pessimistic.
30-39 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.
Table B.9 SV brief (Type 13 record)
Field Item Type Value Meaning
0 Output record type Char 0Dh Brief satellite information output record
1 Record length Char Bytes in record
2 Number of SVs Char 00h-18h Number of satellites included in record
†
The following bytes are repeated for Number of SVs
PRN Char 01h-20h Pseudorandom number of satellites (1-32)
SV Flags1 Char See
Table B.18
First set of satellite status bits