Definition Of GPS
GPS stands for Global Positioning System. It is a radio navigation system that used in land, sea and sirborne to determine the exact location, time and velocity irrespective of weather conditions. It was first used by the US military in the year 1960s.
How GPS Works?
There are at least 4 GPS satellites in lone of sight to a receiver on the earth. The transmitter GPS send information about the position and time to the receiver GPS at fixed intervals of time. The signals that are sent to the receiver devices are radio waves. By finding the difference in time between the signal that was sent from the GPS satellite to the time the GPS receives, the distance between the GPS receiver and the satellite can be calculated. Using the trilateration process, the receiver locates its position as the signals are received from at least 3 satellites.
For a GPS to calculate a 2-D position which includes the latitude and longitude, minimum 3 satellites are required and for a 3-D position which includes latitude, longitude and an altitude, minimum 4 satellites are required.
What Is Trilateration?
Trilateration is defined as the process of determining the location based on the intersections of the spheres. The distance between the satellite and the receiver is calculated by considering a 3-D sphere such that the satellite is located at the center of the sphere. USing the same method, the distance for all the 3 GPS satellite from the receiver is calculated.
Following are the parameters that are calculated after the trilateration:
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