The Global Positioning System, commonly known as GPS, is a worldwide navigation satellite system that accurately provides location, velocity, and time synchronization.
Utilized in various technologies such as cars, smartphones, and watches, GPS aids in navigating from one point to another. Discover more about GPS, including its mechanics, past, and forthcoming innovations, through this comprehensive article.
What is GPS and how does it work?
The GPS is a navigation mechanism that utilizes a receiver, algorithms, and satellites to synchronize data for travel by air, sea, or land.
The constellation of 24 satellites resides in six Earth-centered orbiting planes, with each plane containing four satellites, which move at a speed of 14,000 km/h above the Earth at a distance of 20,000 km.
While only three satellites are required to determine a location on the Earth’s surface, a fourth one is often utilized to verify the data received from the other three. Furthermore, by adding a fourth satellite, we can calculate the altitude of a device, moving us into the three-dimensional space.
What are the three elements of GPS?
The GPS system comprises of three different segments that work in unison to provide location information. These segments include the Space Segment consisting of circulating satellites transmitting signals on geographical position and time, the Ground Control Segment with Earth-based monitor stations, master control stations and ground antenna for tracking and operating satellites in space and monitoring transmissions, and the User Equipment Segment with GPS receivers and transmitters such as watches, smartphones and telematic devices.
- Space (Satellites) — The satellites circling the Earth, transmitting signals to users on geographical position and time of day.
- Ground control — The Control Segment is made up of Earth-based monitor stations, master control stations and ground antenna. Control activities include tracking and operating the satellites in space and monitoring transmissions. There are monitoring stations on almost every continent in the world, including North and South America, Africa, Europe, Asia and Australia.
- User equipment — GPS receivers and transmitters including items like watches, smartphones and telematic devices.
How does GPS technology work?
GPS works through a technique called trilateration. Used to calculate location, velocity and elevation, trilateration collects signals from satellites to output location information. It is often mistaken for triangulation, which is used to measure angles, not distances.
Satellites orbiting the earth send signals to be read and interpreted by a GPS device, situated on or near the earth’s surface. To calculate location, a GPS device must be able to read the signal from at least four satellites.
Each satellite in the network circles the earth twice a day, and each satellite sends a unique signal, orbital parameters and time. At any given moment, a GPS device can read the signals from six or more satellites.
A single satellite broadcasts a microwave signal which is picked up by a GPS device and used to calculate the distance from the GPS device to the satellite. Since a GPS device only gives information about the distance from a satellite, a single satellite cannot provide much location information. Satellites do not give off information about angles, so the location of a GPS device could be anywhere on a sphere’s surface area.
When a satellite sends a signal, it creates a circle with a radius measured from the GPS device to the satellite.
When we add a second satellite, it creates a second circle, and the location is narrowed down to one of two points where the circles intersect.
With a third satellite, the device’s location can finally be determined, as the device is at the intersection of all three circles.
That said, we live in a three-dimensional world, which means that each satellite produces a sphere, not a circle. The intersection of three spheres produces two points of intersection, so the point nearest Earth is chosen.
When a device is in motion, its distance to the satellite (as measured by its radius) constantly changes. This dynamic variation in the radius generates new spheres, which help us determine the device’s current position. By combining this data with the time signals coming from the satellite, we can calculate the velocity of the device, as well as the distance remaining to reach our intended destination. The estimated time of arrival (ETA) can also be determined based on these calculations. In summary, with the help of satellite technology, we can precisely track the movements of devices, and accurately predict their progress towards a certain location.
What are the uses of GPS?
GPS is a powerful and dependable tool for businesses and organizations in many different industries. Surveyors, scientists, pilots, boat captains, first responders, and workers in mining and agriculture, are just some of the people who use GPS on a daily basis for work. They use GPS information for preparing accurate surveys and maps, taking precise time measurements, tracking position or location, and for navigation. GPS works at all times and in almost all weather conditions.
There are five main uses of GPS:
Location — Determining a position.
Navigation — Getting from one location to another.
Tracking — Monitoring object or personal movement.
Mapping — Creating maps of the world.
Timing — Making it possible to take precise time measurements.
Some specific examples of GPS use cases include:
Emergency Response: During an emergency or natural disaster, first responders use GPS for mapping, following and predicting weather, and keeping track of emergency personnel. In the EU and Russia, the eCall regulation relies on GLONASS technology (a GPS alternative) and telematics to send data to emergency services in the case of a vehicle crash, reducing response time. Read more about GPS tracking for first responders.
Entertainment: GPS can be incorporated into games and activities like Pokémon Go and Geocaching.
Health and fitness: Smartwatches and wearable technology can track fitness activity (such as running distance) and benchmark it against a similar demographic.
Construction, mining and off-road trucking: From locating equipment, to measuring and improving asset allocation, GPS enables companies to increase return on their assets. Check out our posts on construction vehicle tracking and off-road equipment tracking.
Transportation: Logistics companies implement telematics systems to improve driver productivity and safety. A truck tracker can be used to support route optimization, fuel efficiency, driver safety and compliance.
Other industries where GPS is used include: agriculture, autonomous vehicles, sales and services, the military, mobile communications, security, and fishing.
How accurate is GPS?
GPS device accuracy depends on many variables, such as the number of satellites available, the ionosphere, the urban environment and more.
Some factors that can hinder GPS accuracy include:
Physical obstructions: Arrival time measurements can be skewed by large masses like mountains, buildings, trees and more.
Atmospheric effects: Ionospheric delays, heavy storm cover and solar storms can all affect GPS devices.
Ephemeris: The orbital model within a satellite could be incorrect or out-of-date, although this is becoming increasingly rare.
Numerical miscalculations: This might be a factor when the device hardware is not designed to specifications.
Artificial interference: These include GPS jamming devices or spoofs.
Accuracy tends to be higher in open areas with no adjacent tall buildings that can block signals. This effect is known as an urban canyon. When a device is surrounded by large buildings, like in downtown Manhattan or Toronto, the satellite signal is first blocked, and then bounced off a building, where it is finally read by the device. This can result in miscalculations of the satellite distance.
Global Navigation Satellite Systems (GNSS)
A GPS is considered to be a Global Navigation Satellite System (GNSS) — meaning it is a satellite navigation system with global coverage. As of 2020, there are two fully operational global navigation satellite systems: the U.S. navigation signal timing and ranging (NAVSTAR) GPS and Russia’s Global Navigation Satellite System (GLONASS). The NAVSTAR GPS consists of 32 satellites owned by the U.S. and is the best-known and most widely-utilised satellite system. Russia’s GLONASS consists of 24 operational satellites with three remaining as spares or in testing.
Other countries are also racing to catch up. The EU, for example, has been working on Galileo, which is expected to reach full operation capacity by the end of 2020. China is also building the BeiDou Navigation Satellite System, with 35 satellites planned to be in orbit by May 2020. Japan and India are also well on their way with their own regional systems, the Quasi-Zenith Satellite System (QZSS) and the Indian Regional Navigation Satellite System (IRNSS), respectively.
GPS vs GNSS Devices
Though GPS is a subset of GNSS, receivers are differentiated as GPS (meaning GPS-only) or GNSS. A GPS receiver is only capable of reading information from satellites in the GPS satellite network, while the typical GNSS device can receive information from both GPS and GLONASS (or more than these two systems) at a time.
A GNSS receiver has 60 satellites available for viewing. While a device only needs three satellites to determine its location, accuracy is improved with a larger number of satellites. The chart below shows an example of the number of satellites available (shown in green), along with its signal strength (height of the column), to a GPS receiver. In this case, 12 satellites are available.
Typical GPS-only test board showing 12 satellite signals (green), using U-Center software.
A GNSS device can see more satellites, which helps improve device accuracy. In the chart below, there are 17 available satellites. Green bars are part of GPS and blue bars are part of GLONASS.
Typical GNSS test board showing 17 satellite signals (GPS = green; GLONASS = blue), using U-Center software.
A larger number of satellites providing information to a receiver enables the GPS device to calculate location with greater precision. More satellites give a device a better chance of getting a positional fix when the receiver has calculated the location of the user.
That being said, GNSS receivers have some drawbacks:
The cost of GNSS chips are higher than those of GPS devices.
GNSS uses a wider bandwidth (1559-1610 MHz) than GPS (1559-1591 MHz).This means standard GPS radio frequency components, such as antennas, filters and amplifiers, cannot be used for GNSS receivers, resulting in a greater cost impact.
Power consumption would be slightly higher than with GPS receivers as it connects to more satellites and runs the calculations to determine location.
The Future of GPS Technology: Advancements and Innovations
GNSS receivers are expected to become smaller, more accurate and more efficient, and GNSS technology is set to penetrate even the most cost-sensitive GPS applications.
Scientists and rescue workers are finding new ways to use GPS technology in natural disaster prevention and analysis in the event of an earthquake, volcanic eruption, sinkhole or avalanche. For the COVID-19 pandemic, researchers are looking at using cellphone location data to assist with contact tracing in order to slow down the spread of the virus.
The launch of new GPS III satellites will refine GPS accuracy to 1-3 meters, improve navigation abilities, and longer-lasting components as early as 2023. By broadcasting on the L1C civilian signal for interoperability with other satellite systems.
The next generation of GPS satellites will include better signal protection, decreased susceptibility to signal jamming and more maneuverability to cover dead zones.
The National Aeronautics and Space Administration’s (NASA) Deep Space Atomic Clock is set to use a powerful onboard GPS satellite to help provide better consistency in time for future astronauts embarking on deep space journeys.
The importance of GPS technology in various aspects of our lives has prompted countries all over the world to invest in developing and upgrading their own GPS systems. These efforts are aimed at increasing the accuracy of the GPS signals and improving the overall reliability of the systems. As technology continues to advance, new GPS capabilities are being explored and implemented to enhance its usefulness in various industries such as aviation, navigation, and transportation. With the continuous progress being made in GPS innovation and development, the benefits and applications of this technology are becoming more widespread and impactful.