Basic Breakdown of the GPS

Basic Breakdown of the GPS

Nowadays, it is hard to imagine a ride, especially in a less-known area, without a GPS. These smart positioning systems are used everywhere: in planes, ships, cars, motorcycles, etc..

More importantly, they answer a very important question for the human: Where am I on the Earth? The GPS 101 basics define this system as a satellite radio navigation global positioning system. It was developed in 1973 by the U.S. Department of Defense (DoD). Areas of use, except the above mentioned and well-known ones, include military, geodesy, forestry, geology, geophysics, geography, hydrography, agronomy, etc. Shortly, all the professions that need fieldwork and all the users at sea, land and air trying to determine the spatial positions, speeds and exact times 24 hours a day, regardless of atmospheric conditions use the GPS. The accuracy of GPS is higher than that of any other radio navigation system so far.

GPS is a satellite-based system that uses a constellation of 24 satellites to give the user the exact position. It is very important to point out and define term ‘exact’. For a soldier in the desert, exactly means 15 m. For a boat captain in the coastal waters, exactly represents only 5 m. Surveyors know that exactly means 1 cm or even less. GPS can be used to achieve all the accuracy in all of the above applications and professions. Accordingly, the difference is only in the type of the GPS receiver used by the different users.

The system is composed of three parts. We, the common mortals, know only of the gps user segment, i.e. the receiver and the antenna. However, this miraculous system has two more complex parts, the cosmic segment and the control segment (units). The cosmic part contains satellites in the space, while the control units, positioned on the equator, are responsible for controlling the cosmic part of the system, i.e. the satellites.

The ever-expanding use of GPS is accompanied by constant development and innovations of the GPS receivers. They become smaller, faster, more reliable and cheaper all the time. Today’s hand-held mobile phone GPS receivers have the ability to simultaneously monitor up to 12 satellites, enabling them to work in areas of lower signal reception, for example in the forest, narrow canyons or streets. Furthermore, almost all handheld devices allow the storage of 500 or more points within the geographical coordinates and 20-point routes containing about 30 points. Newer handheld GPS devices have built-in maps of a particular area (eMAP, GPS III Plus, Street Pilot, etc.). The future of the GPS is clearly very bright. However, the variety of possible uses of this system and the innovations the scientists are preparing are yet to be seen.