FCC Exam Question: 28C1

What is the usual arrangement of GPS satellites?

A. 18 satellites in 3 orbital planes, 6 satellites in each plane, 23,400 km altitude and 55 degrees inclination.
B. 24 satellites in 6 orbital planes, 4 satellites in each plane, 20,200 km altitude and 55 degrees inclination.
C. 30 satellites in 5 orbital planes, 6 satellites in each plane, 20,200 km altitude and 60 degrees inclination.
D. 36 satellites in 6 orbital planes, 6 satellites in each plane, 23,600 km altitude and 60 degrees inclination.
Correct Answer: B

Explanation: The Global Positioning System (GPS) is meticulously engineered to provide continuous, worldwide positioning, navigation, and timing services. This requires a specific arrangement of satellites to ensure that a receiver can always "see" enough satellites (at least four) for accurate triangulation. The standard GPS constellation consists of a minimum of 24 operational satellites, distributed strategically across 6 orbital planes. There are typically 4 satellites in each of these planes. These satellites orbit in Medium Earth Orbit (MEO) at an altitude of approximately 20,200 km (12,550 miles) with an inclination of 55 degrees relative to the equator. This precise configuration ensures global coverage and the necessary geometric diversity for reliable signal reception and position calculation by GPS receivers. The other options list incorrect numbers for satellites, orbital planes, altitudes, or inclinations, which would not achieve the required global coverage and performance of the GPS system.

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Includes Elements 1, 3, 6, 7R, 8, and 9.