ABSTRACT
The philosophy underlying any technology can possibly be divided into three sections: first, what the technology is; second, why and how the technology has been developed; and third, what the technology is used for. Before we start discussing the technology in detail and try to understand its usage or applications, let us take a quick tour of how and why the Global Navigational Satellite System (GNSS) technology was developed. This chapter is actually a prelude to GNSS, which includes basic concepts of navigation and positioning—points of reference, 2D & 3D trilateration, etc. It also includes a brief history of navigation systems to demonstrate why and how the modern navigation system has evolved starting from the Celestial Age. The history of the Radio Age has been documented with discussions on Lorenz, GEE, OMEGA, and LORAN. The Satellite Age has been emphasized to document its important developmental landmarks. The readers may read this chapter to prepare themselves before entering into the greater context of GNSS technology.
