Interestingly enough, all GPS trackers that you find on the market today are very similar. Even though they may look different, or may be priced very different, they all have the same basic principal.
First, a little background on GPS or Global Positioning Systems. The Global Positioning System (GPS) is a U.S.-owned utility that provides users with positioning, navigation, and timing (PNT) services. Consisting of 27 satellites at an altitude of 12,550 miles above surface, each satellite circles the earth twice per day.
The GPS system consistently delivers high performance and high accuracy position and timing information, thanks to the hard work of the men and women of the US Air Force’s 2nd Space Operations Squadron and the Air Force Reserve’s 19th Space Operations Squadron. Together, these highly skilled members keep the GPS satellites flying 24/7 with high availability and high accuracy for both citizens and military users alike.
Each GPS tracker contains a very sensitive GPS receiver. By using trilateration, the GPS receiver is able to determine the position in space and time. Each GPS satellite continuously transmits precise timing information that can be used to calculate the distance from the GPS tracker to the GPS satellite. Knowing that the information is transmitted at the speed of light, one can calculate the distance (ignoring relativistic differences for simplicity). After the distance is calculated from 4 or more satellites, the receiver is able to determine its position.
After the GPS tracker determines the location, it must transmit that information to a GPS tracking server. This server is hosted on the internet, and receives position information from thousands of GPS trackers in real time. Normally, a GPS tracker will transmit its position information via a cellular connection to the main GPS tracking server. However, 2-way satellite technology does exist, and allows certain GPS trackers to communicate where no cellular infrastructure exists. Imagine a cruise ship in the middle of the ocean.
This position information is then stored in a database, and made available to the end user via a secured channel. Data is generally retained in the database for several months to a year depending on the tracking provider.
Hopefully this helps clarify some of the mysteries involved with GPS trackers.