GPS vs. GNSS: Understanding PNT Satellite Systems
Not so fast. Not all systems are the same, and when it comes to business use, it's vital to understand the nuances. Here's a quick rundown that should cut through the noise to help you get a clear signal.
Positioning, Navigation and Timing Systems
A GNSS, or Global Navigation Satellite System, is a generic name for a group of artificial satellites that send position and timing data from their high orbits. The GPS, or Global Positioning System, is just one of the many different sets of satellites that can provide such data.
Most satellite navigation systems operate on similar principles. The satellites are arranged in controlled and carefully monitored orbits, which except for regional enhancements are chosen to ensure even coverage globally.
Since the individual satellites maintain their relative positions, they form stable artificial constellations. Each satellite is transmits its time and position, so that a receiver on the ground can use this signals to, in essence, triangulate in time and space to get its position and the time.
These satellite constellations vary in terms of their orbital heights and the speeds at which they whiz around their orbits. Other technical distinctions include the fact that they employ mostly unique radio frequency bands for their data transmissions.
No satellite navigation system is perfect. For instance, it takes time to prepare and launch reliable devices, and keeping them running is no minor feat. A ground-based receiver needs signals from multiple transmitters to get an accurate timing or positional fix, and the most populated systems only include a few dozen satellites. In other words, loss of a single signal may have a more significant impact in a constellation with fewer members to spare in the first place.
The U.S. spent years dominating the scene with the Global Positioning System. Even with the later addition of Russia's GLONASS, the options remained limited.
More recently, however, the playing field has become host to the European Union's global Galileo and China's regional BeiDou, once known as COMPASS. These systems are scheduled to be fully operational by 2020.
As nations compete to create functional, accurate, and secure satellite positioning and timing networks, it is only natural to differentiate between the diverse groups of artificial constellations.