GPS stands for Global Positioning System. It is a radio navigation tool that works across the world by linking to 24 satellites and associated ground stations. The GPS continues to be funded mainly by the DoD (U.S. Department of Defense), because it was originally developed for the U.S. military. Today, however, anybody can own a GPS tracker and use it as they see fit. The SPS (Standard Positioning Service) is free and unrestricted to use.
How a GPS Tracker Works
GPS tracking allows someone to pinpoint exactly where something that is fitted with the tracker is located. They can place these devices in cars, cellphones, or standalone GPS devices that are either portable or fixed. These devices send information to and from the satellites, determining exact location. At the same time, they can track movement. Hence, businesses could use these trackers to determine where a delivery truck is, or it could be used by a parent to determine the location of their child, or art galleries can use them to track artworks in transit.
This is achieved through the GNSS (Global Navigation Satellite System). This is a network in which satellites are incorporated, sending microwave signals to the GPS systems. These then bounce back, providing information on location but also direction, time, and speed. Additionally, this information can be logged. Hence, historic and real time navigation data can be available.
Any GPS device sends out specialized satellite signals, which are then received and processed. These can calculate location as well as time and velocity. In fact, it is even possible for these to represent the data they collect in a 3D manner using just four GPS signals. The GPS Space Segment is made up of 27 satellites that orbit the Earth. 24 of those are operational and the other three are spares in case of failure. Every 12 hours, they complete a full orbit of the Earth and continuously send radio signals that are received by the GPS devices.
Controlling the system is done through various tracking stations all over the world. These stations are in constant contact with the GPS signals, which orbit the earth. The microwave carrier signals, meanwhile, are transmitted through space vehicles. Anyone using a GPS system essentially has a GPS receiver in their hands that converts signals from space, which then shows location, speed and time.
Understanding exactly how the system works is surprisingly easy. It is based on trilateration, which is a very simple mathematical principle. It is based on two categories, being 2D and 2D trilateration. To make the calculation, a GPS receiver only has to know two things:
- The location that they are tracing, for which they use the three satellites nearest to that location.
- The distance between those Space Vehicles and the location.
Modern GPS devices have multiple receivers fitted to them, which means they can pick up the signals from more than three satellites at the same time, picking up electromagnetic energy radio waves traveling at the speed of light.