BUET '15 batch entrance day magazine 1 | Page 131

cªeÜ direction . Our infographic describes how the distances from 3 satellites calculate the ground or 2D position of an user segment on earth . INFOGRAPHIC HOW GPS WORKS FACTS AND FIGURES DEMONSTRATING THE GLOBAL POSITIONING SYSTEM - Sheikh Asif Imran Shouborno,EEE Introduction Description GPS is an implementation of a constellation of satellites. These satellites are positioned 20,000 km above the ground , and move at a speed of 14,000 kph. Every satellite broadcast two frequencies - 1,575.42 MHz (called Coarse Acquisition , CA, or L 1 ) and 1,227.60 MHz (called Precision, P, or L 2 ) . Combined , CA and P forms an encrypted code, Y. The waveform of Y measures distance between a sat and the GPS receiver , but cannot measure the Our Infographic satiates the desire to know about the following facts : ➔ How many GPS satellites are there ? ➔ What is the number of GPS sats to confirm a position in 2D or 3D ? ➔ How did it all start ? 125