A GPS receiver determines its position by measuring
- AThe angle of arrival of signals from at least three satellites
- BThe time difference between transmission and reception of signals from multiple satellites, then converting to pseudorangesCorrect
- CThe Doppler shift of signals from a single satellite over time
- DThe signal strength from the nearest satellite
Solution
Concept
GPS positioning mechanism via satellite signal transit time
Formula
Pseudorange = c × δt
Step-by-step solution
1. GPS satellites broadcast precision time codes using atomic clocks. 2. The receiver detects the time difference between signal broadcast and arrival, computing pseudoranges (distance = speed of light × time). 3. Measuring pseudoranges from at least four satellites solves the simultaneous equations for latitude, longitude, elevation, and receiver clock offset. Answer: B
Explanation
A GPS receiver determines its three-dimensional position using satellite trilateration based on time-of-flight measurements. The receiver records the time taken by coded radio signals to travel from multiple satellites to the receiver antenna, calculates pseudoranges by multiplying by the speed of light, and solves for coordinates and clock bias. Hence, option B is correct.
Why the other options are wrong
A) GPS uses distance trilateration, not angular triangulation. C) Doppler shift is used in older Transit satellite systems or velocity tracking, not basic point positioning. D) Signal strength indicates link quality, not geometric distance.
Shortcut
GPS = Time difference × c -> Pseudorange -> Trilateration from 4+ satellites.
Common mistake
Assuming GPS works by measuring angle of arrival (triangulation) rather than signal travel time (trilateration).
Correct answer: B) The time difference between transmission and reception of signals from multiple satellites, then converting to pseudoranges