FS - Fundamentals of Surveying GPS and GNSS Technology Flashcards
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Read the first 6 FS - Fundamentals of Surveying GPS and GNSS Technology flashcards as text
What is the geoid used for in GPS height conversions?
Answer: An equipotential surface approximating mean sea level
The geoid is an equipotential gravitational surface approximating mean sea level, used to convert GPS ellipsoidal heights to orthometric (elevation) heights.
What is the role of an ephemeris in GPS positioning?
Answer: It describes the orbital parameters of each satellite
An ephemeris contains orbital parameters describing each GPS satellite's position and velocity, enabling receivers to compute satellite locations during observations.
What is the difference between GPS accuracy and precision?
Answer: Accuracy measures closeness to true value; precision measures repeatability
Accuracy describes how close a measurement is to the true value, while precision describes the repeatability or consistency of repeated measurements.
In differential GPS surveying, what is the primary purpose of the base station?
Answer: To provide known-position corrections to improve rover accuracy
The base station occupies a point with known coordinates and transmits correction data to the rover to remove common errors and improve positional accuracy.
What is the typical horizontal accuracy achievable with static GPS control surveying?
Answer: Plus or minus 1 centimeter
Static GPS surveying typically achieves horizontal accuracies of 1 centimeter or better when proper procedures and sufficient observation time are used.
What is the WGS84 ellipsoid used as in GPS surveying?
Answer: The horizontal datum and mathematical surface for GPS coordinate computations
WGS84 (World Geodetic System 1984) is the global ellipsoid and reference frame on which all GPS coordinates are computed.