About GPS

GPS is short for Global Positioning System. The name says exactly what GPS is, namely a system that can be used around the earth to determine where you are. The GPS system was developed by the Department of Defense of the United States under the name of NAVSTAR GPS. The first satellite was launched in 1978. In 1995 there were 24 active satellites and the system was fully operational. From 1995, there are still satellites sent into space to replace failed ones and expand the system up to now 32 active GPS satellites.

The signal transmits a GPS satellite contains information such as the number of the satellite, the location of the satellite in space, and the date and time that the signal was sent. A GPS receiver thus knows when the signal was transmitted. The receiver also knows when the signal is received because an internal clock is in the GPS. GPS also knows how quickly the signal went through the area (299,792 km / s). With all these data, the GPS determine the distance to the satellite.
Because a GPS receiver knows where you are, it can also indicate the direction to a specified destination. A GPS (GPS receiver is often called GPS or GPSr) thereby replacing map and compass. And that’s good news for anyone who is not as easy as that, because navigating with a GPS is very simple. The satellite signals are also free and open to everyone.

The GPS receiver combines the distance to the satellite with the information on the location of the satellite. This brings GPS into a number of options where you can be in the room. Forming potential locations as it were a sphere around the satellite. If you receive a signal from a second satellite, you find yourself at the intersection of two spheres (which is a circle). And if you receive signals from three satellites, hold only two points on which all three spheres have in common. One of those points is usually not on the earth, so you know your position. The signal from a fourth satellite makes final location and is used to make more accurate the positioning. That accuracy is approximately 3 meters in the open field.
The GPS system consists of three parts: satellites, ground stations and receivers. The satellites are the heart of the system. There are currently 32 active GPS satellites. They run in six orbits around the Earth at about 20,000 km altitude. The speed of these satellites is so great (approximately 11,000 km / hr) that they once every 12 hours to go around the earth. Continuously they send signals to Earth. These signals can be received by GPS receivers, which they use to determine your position on earth. check the ground and the correct operation of the satellites.
More about phone tracking app best can be found in our booklet About GPS. In the book All about GPS is in a very accessible way explains what GPS is and how you can go hiking, and biking. We look at the use of coordinates, waypoints, routes, maps, Basecamp, POIs etc. The book also includes our acclaimed Do-It-Yourself course. On the basis of clear practical exercises anyone can handle a GPS learning. There are various techniques that can improve the positioning accuracy.


This involves the use of correction signals from ground stations (DGPS). WAAS and EGNOS in Europe, in America are examples of DGPS. Waas / EGNOS is built into the present and GPS, but adds in practice not much matter because the signals from the WAAS / EGNOS satellites can not be well received. GPS is not the only satellite navigation system. Russia has a system called GLONASS. Europe also is working on a satellite navigation system. That system called Galileo. In 2019, Galileo should be operational.

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