Navigation General · GPS & GNSS
Multipath error in GPS occurs when:
- AThe GPS receiver locks onto too many satellites simultaneously
- BSatellite signals reflect off nearby structures before reaching the antenna, causing erroneous range measurements✓ Correct
- CThe GPS antenna is mounted below the vessel's waterline
- DIonospheric delay is not corrected by the dual-frequency model
Explanation
Multipath occurs when GPS signals bounce off superstructure, masts, or other reflective surfaces before arriving at the antenna. The receiver processes the reflected (longer path) signal as if it came directly from the satellite, causing a range error and thus a position error. It is a significant concern on vessels with tall superstructures near the antenna.
Authority: Bowditch (Pub. 9), Ch. 13
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