HTG Explains: How GPS Actually Works
 

We already live in the future. We have handheld devices that use satellites to pinpoint our precise locations almost anywhere on the planet. But have you ever wondered just how GPS works?

GPS devices don’t actually contact satellites and transmit information to them. They only receive data from satellites – data that’s being always-transmitted. However, GPS isn’t the only way devices can determine your location.

http://www.howtogeek.com/137862/htg-...ctually-works/