Raymarine RAYSTAR 120 - How it Works

1-2 Raystar 120 GPS Receiver
The combination of theWAAS, EGNOSand MSAS systems will
provide global satellite based differential GPSaugmentation into the
future.
How it Works
The following description is based on WAAS, but the principles
apply equally to the EGNOS and MSAS systems.
WAAS comprisesthe following components:
• Ground Reference Stations across the USA
• Master Stationslocated at East Coast and West Coast
• Geostationary Satellites located above the equator
The Ground Reference Stations are located atknown positions and
receivedatacontinuouslyfromGPS.The GroundReferenceStations
send their data to the MasterStationswhich calculate the errorof the
GPS-received positions and generate correctional data.
The corrected ‘differential’ signals are then sent to the two
GeostationarySatellites whichbroadcast the corrected data on the
standard GPS frequency, making it available to the user’s
Raystar 120 GPS Receiver.
TheRaystar 120 GPSReceiver usesthecorrectionaldata transmitted
by the Geostationary Satellitesto refine theGPS positional data for
greater accuracy.
WAASis showndiagramatically in Figure 1-2 .
81170_2.BOOK Page 2 Thursday, July 19, 2001 2:36 PM