What is GPS?

GPS is short for Global Positioning System, a satellite-based navigation system developed by the U.S. Defense Department is supported by a network of 27 satellites.

GPS consists of three segments: space segment, control segment / controllers, and user segment. Where space segment consists of 24 operational satellites in orbit at an altitude of 6
20,200 km and an inclination of 55 degrees with a period of 12 hours (the satellite will go back to the same point within 12 hours).

The satellite orbits round so at least there are 6 satellites can be monitored at any point on the earth. The satellites transmit position and time to the users all over the world.

Each satellite transmits two signals, namely L1 (1575.42 MHz) and L2 (1227.60 MHz). L1 signal is modulated with two pseudo-random signal is code P (Protected) code and C / A (coarse / aquisition). L2 signal only carries the code P. Each satellite transmits a unique code so that the receiver (GPS devices) can identify signals from each satellite. At the time of the "Anti-Spoofing" is enabled, then the P code is encrypted and will be henceforth known as code P (Y) code or Y.

GPS devices are reserved for only civilian to receive a code C / A on L1 signal (though the device can take advantage of advanced GPS L2 signal to obtain a more accurate measurement).

GPS devices receive signals transmitted by GPS satellites.
In determining the position, we need at least 3 satellites for positioning the 2-dimensional (latitude and longitude) and 4 satellites for determining the 3-dimensional position (latitude, longitude, and altitude).

The more satellites are obtained, we are positioning accuracy will be higher. To get the signals, GPS devices must be in open space. If the GPS devices we are indoors or dense canopy and the area we are surrounded by tall buildings then the signal will be reduced thus obtained will suSskar to determine the exact position or even not able to determine the position.

Through GPS we can know the existence of an object in the object wherever it is in the face of the earth both on land, sea or air.