The Global Positioning System is a U.S.-owned satellite-based radio navigation system to synchronize location, velocity, and time data. Let’s see what GPS is and how this system works.
An explanation into Global Positioning System (GPS)
What is Global Positioning System?
The Global Positioning System (GPS) is a U.S.-owned navigation system using satellites, a receiver and algorithms to provide accurate information about the geographical location, velocity, and time data for air, sea, and land travel.
There is no doubt that the GPS has contributed to the development of many fields such as land trips, maritime navigation, and various military missions.
The GPS also plays a distinctive role in the fields of surveying, so the system is considered one of the most used measurement tools by geodetic survey engineers due to its accuracy and validity of data.
The Soviet Union successfully launched the world’s first satellite into orbit around the Earth on October 4, 1957.
The idea of launching satellites related to the global positioning system goes back to the year 1960 AD by the United States of America. The program was initially related to the US military only.
With the increase in the number of aircraft accidents in the world and the exacerbation of problems and difficulties related to determining the sites of plane crashes, a US authority considered a sophisticated system that determines the locations of planes on the condition that the system is circulated to all people. And by the year 1995 AD the US administration was able to equip the number of satellites needed to cover the entire surface of the earth.
At the present time, the United States of America is responsible for the maintenance and replacement of the satellites in the event that they are damaged, damaged, or otherwise.
Initially, there were 24 GPS satellites orbiting the Earth every 12 hours at an altitude of 20,180 km. Four GPS satellites were located in each of the six orbits with an orientation of 60 ° between each other. Later, the number of satellites was increased to 32, to improve the accuracy of positioning.
The mechanism of the GPS’s work is through the operation of a GPS receiver, where the device polarizes the signals of four satellites as a minimum, so it can calculate the distance that separates the device from the satellites, which leads to determining the geographic location of the satellites.
Any GPS receiver is localized during the flight measurement time. The more satellites are in the line of sight to the GPS receiver, the more accurate is the positioning.
In general, the global positioning system defines this process with an accuracy ranging from 3 to 50 meters. Some practical systems can specify with millimeter precision, but they are not available for normal public use.
How Does GPS Work?
There are at least four GPS satellites in line of sight to a receiver on the earth. Each satellite sends information about its location and current time to the GPS receiver. This information is sent to the receiver in the form of a signal. These signals are radio signals that travel at the speed of light.
Tracking stations use radio signals to determine the orbits of GPS satellites. The command center transmits orbital data, time corrections, and the location of other satellites. GPS satellites transmit synchronized time and orbital data to Earth at the same time. The GPS receiver listens to these signals and calculates the location using the orbital data. Once the receiver calculates the distance from four or more Global Positioning System (GPS) satellites, it can find out where you are.
Why does GPS need at least 4 satellite signals?
Imagine that a certain person completely lost directions in a desert area, and when he met someone and asked him where he was, he replied that he was 500 kilometers from the city.
There is no doubt that this information will not help a person much in determining his exact location because he can draw a circle around city 1 with a radius of 500 km in any part of the desert area.
But if someone else asked and he answered that you are 550 kilometers away from City 2, things will become easier, because it will be at one of the intersections between the two circuits around City 1 and City 2.
And by obtaining two additional pieces of information from a third and fourth person, the person will be able to determine his whereabouts on the globe.
Based on this principle, the four satellites operate to determine the location on the surface of the globe. Each satellite creates a spherical surface around the satellite.
By calculating intersections, we can narrow the possibilities to a single point. An intersection of three satellites puts us on two possible points. The last satellite gives us the exact location.
And from the intersections of these surfaces with the surface of the globe, the geographical location is determined with high accuracy.
The receivers need three satellites for positioning, while the 4th satellite enhances the measurement and provides the ability to calculate elevation.
