Definition
A precisely surveyed ground station within the Wide Area Augmentation System (WAAS) that continuously receives signals from GPS satellites and forwards the raw data to a wide-area master station. The network of WRSs spread across North America allows the master station to calculate satellite position errors, clock errors, and ionospheric delays, which are then broadcast back to aircraft as correction messages to improve GPS accuracy and integrity.
Plain English
A ground site at a known, exact location that listens to GPS satellites and reports what it hears. By comparing what the satellite signal said with what the ground site knows to be true, the system figures out how wrong the GPS signal is and sends corrections to aircraft.
Context Anchor
Seen in WAAS and NextGen diagrams, especially when explaining how satellite navigation is improved before it reaches the aircraft.
Derivation
Wide-area refers to the large geographic region the station helps cover -- much larger than a single airport. Reference means a fixed, trusted point used for comparison; because the station's exact position is already known, any difference between what GPS reports and what the station knows must be GPS error.
Why Pilots Care
These stations supply the data that produces the corrections enabling WAAS approaches with vertical guidance, improving access to airports in marginal weather.
Intuition Check
Do not picture a pilot-operated radio station or an airport facility. Here, station means a fixed ground site, and reference means its known position is used as the comparison point.
Example Sentence 1
The WAAS signal the aircraft receives starts with raw GPS data collected by wide-area reference stations on the ground.
Example Sentence 2
Aircraft using WAAS approaches rely on data originally gathered by wide-area reference stations across the country.