GPS needs at least ___ signals from satellites for providing geographic location

Correct option is B

The correct answer is (B) 3

Explanation:
• A Global Positioning System (GPS) receiver requires signals from at least 3 satellites to determine a 2D position (latitude and longitude) on the Earth's surface.
• This process is called trilateration. One satellite puts the receiver on a sphere; two satellites narrow it to a circle (where two spheres intersect); and the third satellite narrows it down to two points, one of which is usually impossible (e.g., in space), leaving the correct location.
• To determine a 3D position (latitude, longitude, and altitude), a minimum of 4 satellites is required.
• The fourth satellite is also essential to synchronize the receiver's clock with the atomic clocks on the satellites, correcting for any timing errors.

Information Booster:
• GPS is a US-owned satellite-based radio navigation system.
• India has its own regional navigation system called NavIC (Navigation with Indian Constellation).
• There are typically 24 to 32 satellites in the GPS constellation orbiting at an altitude of about 20,200 km.

Additional Knowledge:
• Precision: While 3 satellites give a basic fix, having more satellites (8-12) significantly improves the accuracy of the location.
• Differential GPS (DGPS): Uses a fixed ground station to provide corrections to GPS signals, bringing accuracy down to centimeters, which is vital for precision farming.