Air Force Space and Missile Museum
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Monitor Station GPS Antenna

Monitor Station GPS Antenna

Display location: Museum rocket garden

Type: AN/FSN-5V

Antenna Specifications

  • L1 Band Radio Frequency: 2575.42 Mhz
  • L2 Band Radio Frequency: 1227.6 Mhz
  • Antenna diameter: 7 feet

In 1984 the Monitor Station Vega Antenna was developed by Space and Missile Systems Center (SMC) for gathering Global Positioning Systems (GPS) signals for processing at the Master Control Station (MCS) so that we can build navigation uploads for the GPS satellites. It was also used for monitoring the navigation signal that we provide to the world free of charge. The antenna was located at Falcon Air Force Base later changed to Schriever Air Force Base on the roof of Building 400. It was replaced with the AOA antenna as part of an initiative to find an antenna that was cheap to procure and met the requirement of the GPS weapon system. The Monitor Station uses a GPS receiver to passively track all satellites in view and thus accumulate ranging data from the satellite signals. The Monitor Station then transmits this information to the MCS which corrects errors in the data due to ionospheric delay, tropospheric refraction, earth rotation, timing errors, etc. The data is used to predict future clock offsets and ephemeris for incorporation into an updated navigation message for the corresponding satellite.