ISABEL RUBIO ARROYO | Tungsteno
The most universal geopositioning system, the GPS (Global Positioning System), is beginning to show signs of wear and tear. Designed in the 1960s by the United States Department of Defence, it has become practically omnipresent in our daily lives. Since it began directing our routes through the first portable navigators available for cars, GPS has become a fundamental tool for air, land and sea navigation, but also for crop planning, natural disaster relief missions and even for playing Pokémon Go. Its functionalities, however, are no longer so precise and current requirements have exposed its limitations, opening the way to solutions that seek to improve and even replace the system.
The first operational GPS satellite was launched in 1978 after years of testing and the efforts of scientists from MIT (Massachusetts Institute of Technology), by means of which it was possible to track objects on the planet’s surface using satellites. The system is composed of three elements: the satellites in orbit around the Earth, the terrestrial monitoring and control stations, and the GPS receivers that users have. In total, a constellation of 24 satellites—plus some reserve satellites—orbiting the Earth at an approximate altitude of 20,200 kilometres providing precise time and location signals at any time and place in the world.
A new generation of satellites
But this precision is often far from accurate. For safety reasons, GPS microwave signals that are generated for civilian use are deliberately degraded, while their broadcast is restricted to a certain frequency. These small errors, however, have been corrected to some extent by the incorporation of differential techniques (DGPS), which provide GPS receivers with corrections to data received from satellites, for greater accuracy in the calculated position.
Another of the deficiencies inherent in this geopositioning system has been its vulnerability. Its signals can be interfered with, making it impossible for the receiver to hear them, and can even be replaced by false ones. For example, North Korea has tried on several occasions to block the GPS system in South Korea, according to The New York Times. Also the elements of the system (satellites, ground control stations and receivers) are exposed to cyberattacks, and there is even specific equipment designed to block GPS transmissions, which could cause a major security problem for governments and countries.
With these limitations, the need to improve and perhaps even replace the system has become essential. The U.S. government, which owns the technology, has already launched a coordinated initiative to improve it that incorporates three elements: the GPS OCX control system, the new GPS III satellites and the MGUE (Military Gps User Equipment) receivers.
With the GPS OCX program, Raytheon, the company in charge of the development, seeks to make the ground control system more robust and less vulnerable. To this end, it is implementing new software based on a mathematical algorithm to improve reception in noisy environments. Together with the new generation of satellites, this will make it possible to increase coverage in areas of difficult access, such as urban canyons and mountainous terrain. In addition, new encryption is being used to prevent signals from being interfered with. The amount invested in the project amounts to 4.2 billion dollars, according to the Defense One portal.
To improve the accuracy of its navigation system, the United States has also launched the GPS III satellites. Aerospace company Lockheed Martin, which is developing this new generation of satellites, states that they will be three times more accurate than their predecessors and are designed to avoid possible interference. In addition, their life will be extended to 15 years, "25% longer than the newest GPS satellites in orbit today." Three such satellites have already been launched. The last one was launched this year by the company Space X.
The new generation of GPS III satellites have a 25% longer life than the current ones. They use the GPS_OCX control system and MGU receivers to improve safety and accuracy. Credit: Astrotech.
GLONASS and Beidou: the alternatives to American hegemony
Although GPS is the most universal, it is not the only system. Among the other existing alternatives are GLONASS, developed by the former Soviet Union and now administered by the Russian Federation, the Chinese satellite navigation system Beidou and even a Europe-wide coordinated initiative, the Galileo project.
It was not until 1996 that the GLONASS system became functional and it took more than a decade for it to achieve coverage of the entire Russian territory. Today, its use is free and covers practically the entire globe.
China's path has been more recent. From its beginnings in 2000, it has taken two decades for its satellites to cover the whole world, making Beidou one of the most serious alternatives to the American GPS. In fact, in the Asian giant, 70% of the smartphone market has Beidou-compatible receivers and by official mandate this must be the navigation system available in commercial vehicles.
In fact, devices with satellite positioning receivers such as smartphones can be connected to either network. Thus, they often rescue the sparsely-covered dark areas by having one of the two systems report the geographic position. The coexistence between the different systems became a reality in the past decade. For reference, Apple added GLONASS support to the iPhone 4s in 2011; and all their new models since 2014 are also Galileo, QZSS and BeiDou compatible.
Precision errors, vulnerability to cyber attacks or even reception difficulties have led to the development of new alternative systems to GPS. Credit: Lockheed Martin.
Galileo: Europe's commitment to precision
The United States is not the only power trying to achieve a more precise positioning system. The reality is that with today's navigation systems, GPS or GLONASS, it is not possible to meet the rigorous safety standards that some civil applications, such as air navigation, require. In order to solve these problems, Europe is developing EGNOS (European Geostationary Navigation Overlay Service), a system that makes it possible to reduce these errors in positioning by means of amplified signals through SBAS (Satellite-Based Augmentation System).
This project is part of the Galileo project, the commitment of the European Union and the European Space Agency (ESA) to avoid having to depend on GPS or GLONASS. This European positioning system began to take shape in 1999; however, it was not until 2011 that the first satellites of the project were launched. The aim is for this alternative to be five times more accurate than GPS in terms of location. ESA claims that its technology will allow position to be determined in real time with a margin of error of less than one metre. Accordingly, if GPS can locate a person on a train or a bus, Galileo will also be able to identify the rail track or the lane of the road being travelled on.
The project, which is scheduled to end this year 2020, will consist of a constellation of a total of 30 satellites —27 operational plus three reserve satellites—that will orbit at an altitude of 23,222 kilometres above the Earth. Unlike GPS or GLONASS, which were designed for military use, Galileo is conceived as a system for civilian use only. Even so, all these systems pursue common objectives: to achieve independence in terms of geolocation and to serve billions of users around the world over the next few decades.