| definition |
- The Global Position System (GPS), counterpart to the Russian Global Navigation System (GLONASS), is a United States Department of Defense (DoD) developed, worldwide, satellite-based radionavigation system that will be the DoD's primary radionavigation system well into the next century. The constellation consists of 24 operational satellites. The U.S. Air Force Space Command (AFSC) formally declared the GPS satellite constellation as having met the requirement for Full Operational Capability (FOC) as of April 27, 1995. Requirements include 24 operational satellites functioning in their assigned orbits and successful testing completed for operational military functionality. GPS consists of three segments, the SPACE, CONTROL and USER Segment:
1. The SPACE segment consists of 24 operational satellites in six orbital planes, (four satellites in each plane). The satellites operate in circular 20,200 km orbits at an inclination angle of 55 degrees and with a 12-hour period. The position is therefore the same at the same sidereal time each day, i.e. the satellites appear four minutes earlier each day.
2. The CONTROL segment consists of five Monitor Stations, three Ground Antennas, and a Master Control Station (MCS) located at Falcon AFB in Colorado. The monitor stations passively track all satellites in view, accumulating ranging data. This information is processed at the MCS to determine satellite orbits and to update each satellite's navigation message. Updated information is transmitted to each satellite via the Ground Antennas.
3. The USER segment consists of antennas and receiver-processors that provide positioning, velocity and precise timing to the user. GPS provides two levels of service, Standard Positioning Service and the Precise Positioning Service. The Standard Positioning Service (SPS) is a positioning and timing service which will be available to all GPS users on a continuous, worldwide basis with no direct charge. The Precise Positioning Service (PPS) is a highly accurate military positioning, velocity and timing service which will be available on a continuous, worldwide basis to users authorized by the U.S.
[Summary provided by NASA.]
Group: Platform_Details Entry_ID: GPS-36 Group: Platform_Identification Platform_Category: Navigation Platforms Platform_Series_or_Entity: GPS (Global Positioning System) Short_Name: GPS-36 Long_Name: Global Positioning System Satellites-36 End_Group Group: Platform_Associated_Instruments Short_Name: GPS Short_Name: GPS RECEIVERS End_Group Group: Orbit Orbit_Altitude: 20,200 km Orbit_Inclination: 64.8 degrees Period: 718 minutes Perigee: 20,030 km Orbit_Type: MEO > Semi-Synchronous > Navigation End_Group Creation_Date: 2007-02-12 Online_Resource: http://ilrs.gsfc.nasa.gov/cgi-bin/satellite_missions/select.cgi?order=by_name&sat_code=GP36&sat_name=GPS-36&sat_no=9401601&tab_id=general Sample_Image: http://ilrs.gsfc.nasa.gov/images/gps.gif Group: Platform_Logistics Launch_Date: 1994-04-10 Primary_Sponsor: U.S. Department of Defense End_Group End_Group
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