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APPENDIX
AP-12
6. What is WAAS?
WAAS, available in North and South America mainly, is a provider in the worldwide SBAS
(Satellite Based Augmentation System) navigation system. SBAS provides GPS signal
corrections to SBAS users, for even better position accuracy, typically better than three
meters. There are three more SBAS providers, MSAS (Multi-Functional Satellite
Augmentation System), EGNOS (Euro Geostationary Navigation Overlay Service) and
GAGAN (GPS Aided Geo Augmented Navigation). All providers are compatible with one
another, thus providing seamless position fixes to SBAS users. The illustration below shows
the coverage area of the SBAS. (Accuracy may be affected when using a GEO satellite not
within your current location.) This manual uses WAAS for these three providers generically.
WAAS
MSAS
EGNOS
GAGAN
Provider Satellite type Longitude Satellite No.
WAAS Intelsat Galaxy XV 133W 135
TeleSat Anik F1R 107.3W 138
EGNOS Inmarsat-3-F2/AOR-E 15.5W 120
Artemis 21.5E124
Inmarsat-3-F5/IOR-W 25E 126
MSAS MTSAT-1R 140E 129
MTSAT-2 145E 137
GAGAN Inmarsat-4-F1/IOR 64E 127