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GPS: Global Positioning System

GPS stands for Global Positioning System. It was developed by the Department of Defense in the 1980's.
The system is now being widely used by civilians everyday. The GPS system sends microwave signals to a receiver, that gives it it's location.
GPS works on the principle of triangulation.

Here is how the data looks coming out of a GPS unit. This example is one of a GPRMC sentence, which is one of the most common outputs by a GPS unit, is described below.

$GPRMC,123519,A,4025.850,N,08515.480,W,022.4,084.4,071281,003.1,W*43

• RMC Recommended Minimum sentence
• 123519 Fix taken at 12:35:19 UTC
• A Status A=active /* The data status. [A] for valid data, [V] for invalid.
• 4025.850,N Latitude 40 deg 25.850' N
• 08515.480,W Longitude 85 deg 15.480' W
• 022.4 Speed over the ground in knots
• 084.4 Track angle in degrees True
• 071281 Date - 7th of December 1981
• 003.1,W Magnetic Variation /* The difference of magnetic direction from true north.
• *43 The checksum data, always begins with *