What is GPS?
The Global Positioning System (GPS) is a worldwide radio-navigation system formed from a constellation of 24 satellites and their ground stations.
GPS uses these “man-made stars” as reference points to calculate positions accurate to a matter of meters. In fact, with advanced forms of GPS you can make measurements to better than a centimeter!
In a sense it’s like giving every square meter on the planet a unique address.GPS receivers have been miniaturized to just a few integrated circuits and so are becoming very economical. And that makes the technology accessible to virtually everyone.
These days GPS is finding its way into cars, boats, planes, construction equipment, movie making gear, farm machinery, even laptop computers.
Soon GPS will become almost as basic as the telephone. Indeed, at Trimble, we think it just may become a universal utility.
How GPS works?
Here’s how GPS works in five logical steps:
- The basis of GPS is “triangulation” from satellites.
We’re using the word “triangulation” very loosely here because it’s a word most people can understand, but purists would not call what GPS does “triangulation” because no angles are involved. It’s really “trilateration.”
Trilateration is a method of determining the relative positions of objects using the geometry of triangles.
- To “triangulate,” a GPS receiver measures distance using the travel time of radio signals.
- To measure travel time, GPS needs very accurate timing which it achieves with some tricks.
- Along with distance, you need to know exactly where the satellites are in space. High orbits and careful monitoring are the secret.
- Finally you must correct for any delays the signal experiences as it travels through the atmosphere.