How many satellites are in view to provide global GPS operation?

• A. Four
• B. Six
• C. Seven
• D. Five

Answer: (D)

In GPS navigation, each satellite provides a distance measurement (pseudorange) to your receiver. You need four of these measurements to solve for four unknowns: your three coordinates (latitude, longitude, altitude) and the receiver’s clock bias. So four satellites are the minimum to obtain a basic 3D position and accurate time.

Five satellites in view is preferred for global operation because it adds redundancy. That extra measurement helps you verify that the computed position is consistent, reduces the impact of any one faulty or degraded signal (due to multipath, atmospheric effects, or interference), and improves solution reliability if one satellite becomes unavailable. In practice, the GPS constellation is designed so many satellites are visible at once, and having five or more in view ensures robust, continuous navigation anywhere on Earth.