Definition
Unmanned ground-based facilities within the GPS control segment that continuously receive signals from GPS satellites, measure the accuracy of those signals, and forward the data to a master control station for processing into corrected satellite navigation information.
Plain English
Ground stations spread around the world that listen to the GPS satellites overhead, check whether their signals are accurate, and pass that information to a central station that fixes any errors.
Context Anchor
Seen in discussions of GPS components, especially the ground-based system that keeps GPS satellite information accurate.
Derivation
Monitor comes from the Latin monere, meaning 'to warn' or 'to remind.' A monitoring station is one that keeps watch and reports back, which is exactly what these stations do for the GPS satellite signals.
Why Pilots Care
They provide the real-time checks that let pilots trust GPS for en route and approach navigation without undetected errors.
Intuition Check
Monitoring stations are not airport weather stations or cockpit displays. In this GPS context, they are ground sites that watch GPS satellites and feed information to the GPS control system.
Example Sentence 1
Monitoring stations around the world track each GPS satellite as it passes overhead and report any signal errors to the master control station.
Example Sentence 2
Before departure the pilot noted that monitoring stations had flagged no integrity issues for the planned route.