MPC User Manual Rev 0D 81
Appendix B GPS Overview
The Global Positioning System (GPS) is a satellite navigation system capable of providing a highly
accurate, continuous global navigation service independent of other positioning aids. GPS provides
24-hour, all-weather, worldwid e cove rage with position, velocity and timing information.
The system uses the NAVSTAR (NAVigation Satellite T iming And Ranging) satellites which consists
of 24 operational satellites to provide a GPS receiver with at least six satellites in view at all times. A
minimum of four satellites in view are needed to allow the GPSCard to compute its current latitu de,
longitude, altitude with reference to m ean se a level and the GPS system time.
Figure 79: NAVSTAR Satellite Orbit Arrangement
B.1 GPS System Design
The GPS system design consists of thre e p a rts:
• The Space segment
• The Control segment
• The User segme nt
All these parts op erate together to provide accu rate three d imensional pos itioning, timing and velo city
data to users worldwide.
B.1.1 The Space Segment
The space segment is composed of the NAVSTAR GPS satellites. The constellation of the system
consists of 24 satellites in six 55° orbital planes, with four satellites in each plane. The orbit period of
each satellite is approximately 12 hours at an altitude of 20 183 kilometers. This provides a GPS