Section 4: Soil and Water Conservation Engineering
Surveying and Levelling
Subtopic: Total station, introduction to GPS survey
Question Statement:
Which factors influence the positioning accuracy of a Differential Global Positioning System (DGPS) in agricultural field surveying?
Options:
(A) Carrier phase versus pseudorange (code-phase) differential processing
(B) Dilution of Precision (PDOP / GDOP) resulting from satellite constellation geometry
(C) Atmospheric (ionospheric and tropospheric) delay corrections from a reference base station
(D) Battery voltage of the farm tractor
Answer Key:
A, B, C
Step-by-Step Solution & Explanation
DGPS achieves centimeter-level RTK accuracy through carrier phase differential tracking, low PDOP geometry, and real-time ionospheric error cancellation from a base station.