What is gps
What is gps? GPS (Global Positioning System) stands for Global Positioning System. It is a radio-navigation system based on satellites developed and controlled by the Department of Defense of United States of America that allows any user to know their location, speed and height, 24 hours a day, under any weather conditions and in any point of the globe.
After the second world war, the Defense Department insisted on a solution to the problem of the precise and absolute positioning. It took several projects and experiences over the next 25 years, including Loran, Transit etc. All made it possible to determine the position, but were limited in accuracy or functionality. In the beginning of the Decade of 70, a new project was proposed, the GPS.
What is gps has three components: the space, the control and the user.
The spatial component is made up of a constellation of 24 satellites in Earth orbit approximately 20200 km, distributed in 6 orbital planes. These planes are separated by approximately 60 in length and have slopes close to the 55 in relation to the Earth’s equatorial plane. It was designed so that there are at least 4 satellites visible above the horizon at any point on the surface and at any height.
The control component is composed of 5 tracking stations spread across the globe and a main control (MCS – Master Control Station) station. This component tracks satellites, updated their orbital positions and calibrated and synchronized their watches. Another important function is to determine the orbit of each satellite and predict its path during the next 24 hours. This information is sent to each satellite to be transmitted by this, informing the local receiver where you can then find the satellite.
The user component includes all those who use a GPS receiver to receive and convert GPS signal in position, velocity and time. It includes also all the necessary elements in this process, such as antennas and processing software
How does GPS work?
The basics of GPS are based on the determination of the distance between a point: the receiver, others of reference: satellites. Knowing the distance that separates us from 3 points can determine our position relative to those same 3 points through the intersection of 3 circles whose radii are the measured distances between the receiver and the satellite. In reality, needed at least 4 satellites to determine our position correctly, but we leave that for later.
Each satellite transmits a signal that is received by the receiver, this, on the other hand measures the time it takes signals to reach it. By multiplying the time measured by the speed of the signal (speed of light), we obtain the receptor-satelite distance, (distance = speed x time).
However the satellite positioning is not so simple. Get precise measurement of distance is no easy task.
The distance can be determined through the codes modulated wave sent by the satellite (C/A and P codes) or by analysis of the carrier wave. These codes are complicated. The receiver was prepared so that only decode those codes and none more so he is immune to interference generated by natural or intentional sources. This is one of the reasons for the complexity of the code.
What is gps