The Global Positioning system (GPS) also referred to as the NaVStar is a satellite-based navigation system composed of at least 24 satellites. It works anywhere in the world in all-weather conditions and has no subscriptions fee. It was built by the United States military for easy navigation and has been fully operational since 1995.
Modern-day GPS uses a combination of the Russian GLONASS satellites and GPS to achieve accuracy and improved coverage (Thurston, Poiker & Moore, 2003). Currently, the GPS system comprises 31 active satellites in orbits inclined at 55 degrees to the equator. The 3000-4000 pound satellites make two orbits a day and are positioned 20000 kilometers from the earth's surface (Balbirnie, 1999). The orbits are designed in such a way that six satellites are often in view from any location on earth. Each satellite transmits information regarding its position and the current time. The signals from these satellites are transmitted at the speed of light and intercepted by a GPS receiver. During transmission, kinetic energy is put to play as the signals move from the satellites to the GPS receivers. The transmission also operates on the principles of energy conversion, where the potential energy in the satellites produces signals which are transmitted through kinetic energy into GPS receivers. The satellites transmit the exact time when the signal is sent.
GPS satellites transmit at least two low-power radio signals which travel by line of sight. The signals can pass through plastic, glass, and clouds. They, however, cannot go through most solid objects like mountains and buildings. The transmission of signals operates on Newton’s first law of motion that states that a body continues in uniform motion along a straight line unless a force acts on it. In this case, solid objects are forces acting on the signals. The motion and accuracy of the signal is therefore a product of the forces it encounters as it is transmitted to the receiver.