Have You Ever Wondered Just How GPS Works?

The following blog article was written by: Susan Connolly on September 19, 2011.

When you think about the ability that GPS gives us to locate ourselves and others, pinpointing our location with amazing accuracy, it almost seems like magic. Of course, it is in fact based on sound scientific principles and technological advances.

There are 24 satellites in the GPS system that orbit about 12,000 miles above the surface of the earth, completing two orbits every 24 hours. The satellites, powered by solar energy, move around the earth at speeds of around 7,000 miles per hour. These satellites transmit their location and the time, which is the time given by the highly accurate atomic clock that each satellite carries.

Your GPS does not broadcast anything; rather it receives data from any satellites that are in range. The satellites transmit their data by “line of sight”, so while air, glass and plastics aren’t an issue, buildings, mountains and forested areas can cause problems for your GPS.

When your GPS receives a signal from a satellite, it uses the satellite’s location and the time difference between when the signal was sent and received to calculate how far away the satellite is. Of course, simply knowing how far you are from something does not tell you where you are, as you could be north, south, east or west.

Your GPS needs to receive data from three separate satellites so that it can use a concept known as triangulation to calculate its 2-dimensional location – i.e. latitude and longitude. This is all you need for locating yourself on a map. If your GPS can receive data from more than three satellites, then it can also tell you your altitude. Of course, once your GPS knows where you are, it can give you even more information, such as the distance to your destination, your speed, your bearing and more.

While GPS systems are normally very accurate, some factors can interfere with their operation and cause errors. For example, errors in your receiver’s clock, signals bouncing off tall buildings, or atmospheric interference with the signal can all cause your GPS to be less accurate.

Now that you know just how GPS tracking works, you may look at your GPS systems a little differently. By understanding how your GPS works you can understand why it sometimes may not function as normal, for example, when you are in a wooded area or inside a building.

Now that you know a little bit about how GPS works, perhaps you’d like to learn about GPS tracking. This post brought to you by Susan Connolly.