The Global Positioning Systems Directorate is a joint service effort directed by the United States Air Force and managed at the Space and Missile Systems Center, Air Force Space Command, Los Angeles Air Force Base, Calif. The directorate is the Department of Defense acquisition office for developing and producing Global Positioning System (GPS) satellites, ground systems and military user equipment.
GPS is a space-based dual use radio navigation system nominally consisting of a minimum of 24-satellite constellation that provides positioning, velocity and timing to military and civilian users worldwide. GPS satellites, in one of six medium earth orbits, circle the earth every 12 hours transmitting continuous ranging signals. In addition to the satellites, the system consists of a worldwide satellite control network and GPS receiver units that acquire the satellite's signals and compute navigation solutions to provide positioning, velocity and timing to the user.
GPS provides the following:
24-hour, worldwide service
Highly accurate, three-dimensional location information
Precision velocity and timing services
Accessibility to an unlimited number of global military, civilian, and commercial users
As a service to GPS users, the Department of Transportation has established the "Navigation Information Service " (formerly "GPS Information Service") as a point of contact for civil GPS users. Operated and maintained by the United States Coast Guard, the NIS can be reached at (703) 313-5900, seven days a week, 24-hours a day, and at www.navcen.uscg.gov.
Related fact sheets:
Pseudorandom Noise Code Assignments
GPS Public Interface Control Documents
GPS IIR/IIR-M Satellite
GPS IIF Satellite
GPS III Satellite
GPS Operational Control Segment
GPS Advanced Control Segment
Advanced Digital Antenna Production System
Ground Based GPS Receiver Application Module
Military GPS User Equipment