Monitor Stations

Track GPS satellites as they pass overhead

Collect navigation signals, range/carrier measurements, and atmospheric data

Feed observations to the master control station

Utilize sophisticated GPS receivers

Provide global coverage via 16 sites: 6 from the Air Force plus 10 from NGA
→
Master Control Station
• Provides command and control of the GPS constellation
• Uses global monitor station data to compute the precise locations of the satellites
• Generates navigation messages for upload to the satellites
• Monitors satellite broadcasts and system integrity to ensure constellation health and accuracy
• Performs satellite maintenance and anomaly resolution, including repositioning satellites to maintain optimal constellation
• Currently uses separate systems (AEP → & LADO →) to control operational and non-operational satellites
• Backed up by a fully operational alternate master control station
Ground Antennas
• Send commands, navigation data uploads, and processor program loads to the satellites
• Collect telemetry
• Communicate via S-band and perform S-band ranging to provide anomaly resolution and early orbit support
• Consist of 4 dedicated GPS ground antennas plus 7 Air Force Satellite Control
Network (AFSCN) remote tracking stations