Section 4: Soil and Water Conservation Engineering
Surveying and Levelling
Subtopic: Total station, introduction to GPS survey
Question Statement:
To determine an unambiguous three-dimensional ground position (Latitude, Longitude, and Ellipsoidal Altitude) along with receiver clock bias, a GPS receiver requires simultaneous radio signals from a minimum of how many satellites?
Options:
(A) 4 satellites
(B) 3 satellites
(C) 2 satellites
(D) 1 satellite
Answer Key:
A
Step-by-Step Solution & Explanation
A GPS receiver must solve four mathematical unknowns: three spatial coordinates ($x, y, z$) and the receiver clock offset ($Delta t$). Hence, simultaneous pseudorange measurements to at least four non-co-planar satellites are mathematically mandatory. Option A is correct.