Global positioning systems can now be found in many devices and have transformed the way that people interact with their environments. Navigation tools have evolved over the years, and the world has long been on the precipice of something more accurate and intuitive.
Many people believe GPS started with the launch of the Russian satellite Sputnik. Scientists at MIT noticed that the frequency of the radio signals transmitted by the satellite increased as it approached Earth and decreased when it moved away. Satellites could be tracked by measuring the frequency of these radio signals, and thus the locations of receivers on the ground could be tracked by their distance from the satellites. This is essentially the basis behind GPS technology. The United States Navy built the first real satellite navigation system in 1959. Known as TRANSIT, the system was designed to locate submarines and would pave the way for the GPS systems that today are used in vehicles, aircraft, phones, and more.
Satellites are necessary for all GPS systems to work. The Federal Aviation Administration says the baseline satellite constellation in space consists of 24 satellites positioned in six earth-centered orbital planes with four operation satellites and a spare satellite slot in each orbital plane. The system can support up to 30 satellites in orbit. The exact number of satellites operating at any one particular time varies depending on the number of satellite outages and operational spares in orbit. Due to this constellation, the basic GPS signal is accurate at the worst to within approximately 100 meters lateral and 140 meters vertical everywhere on Earth.
People may be surprised at just how far-reaching GPS technology is today. GPS sensors are used on objects to track them, as is the case for fleet vehicle management or finding missing persons. Sensors deliver real-time data on horse races and military missiles. However, navigation GPS in vehicles is where GPS may be much more pervasive on the consumer level.
These systems can not only provide step-by-step directions and mapping, but also they can alert us to traffic jams, provide alternate routes, help people avoid accidents, and even find others you know on the roads nearby.
GPS continues to evolve and be a valuable navigation tool for people around the world.