GPS, or Global Positioning System, is a global navigation satellite system that provides synchronization of position, speed, and time.
GPS is everywhere. You can find GPS systems in your car, smartphone, and watch. GPS helps you get where you are going, from point A to point B.
Table of Contents
- What is GPS, and How Does It Work?
- How Does GPS Work?
- What are the Advantages of GPS?
- Applications of GPS
- How accurate is GPS?
What is GPS, and How Does It Work?
The Global Positioning System (GPS) is a map-reading system that uses satellites, a receiver, and algorithms to synchronize position, speed, and time data for air, sea, and land travel.
The satellite system consists of a constellation of 24 satellites in six orbital planes directed towards the Earth, each with four satellites, which orbit about 20,000 km above the Earth and move at a speed of 8700 mph (14000 km/h),
While we only need three satellites to fabricate a location on Earth’s surface, a fourth satellite is mostly used to validate the information from the other three. The fourth satellite also moves us to the third dimension and allows us to calculate the height of the device
How Does GPS Work?
GPS works through a technique called trilateration, which is used to calculate location, speed, and altitude, the trilature collects signals from satellites to produce location information. It is often confused with triangles, which are used to measure angles rather than distances.
Satellites orbiting the Earth send signals for reading and interpretation using GPS devices located on or near the Earth’s surface. The GPS device must be able to read the signal from at least four satellites to calculate the position.
Each satellite in the network orbits the Earth twice a day, and each satellite sends a unique signal, orbital parameters, and time. The GPS device can read signals from six or more satellites at any time.
A satellite emits a microwave signal that the GPS device accepts and calculates the distance between the GPS device and the satellite. Since a GPS device only provides distance information from a satellite, a satellite cannot provide much location information. The satellites do not transmit angle information, so the position of the GPS device could be anywhere on the surface of the sphere.
When a satellite sends a signal, it generates a circle with a measured radius from the GPS device to the satellite.
When we add another satellite, it creates a second circle, and the location is reduced to one of the two intersection points of the circles.
The third satellite can finally determine the location of the device because it is at the intersection of three circles.
That being said, we live in a three-dimensional world, which means that each satellite produces a sphere, not a circle. The intersection of the three spheres creates two points of intersection, so the location closest to the Earth is chosen.
As the device moves, the radius (distance to the satellite) changes. When the radius changes, new spheres are created, which gives us a new position. These data, combined with the time of the satellite, we can determine the speed, calculate the distance to our destination and ETA.
What are the Advantages of GPS?
GPS is a powerful and reliable tool for companies and organizations in many sectors. Surveyors, scientists, pilots, ship captains, first aid personnel, and mining and agricultural workers are just some of the people who use GPS for their daily work.
Using GPS data, they are used to prepare accurate surveys and maps, to measure time, track position or location accurately, and to navigate. The GPS works at all times and in almost all weather conditions.
Applications of GPS
- Location: Positioning.
- Navigation: How to get from one place to another.
- Monitoring: Monitoring of personal objects or movements.
- Cartography: Creation of world maps.
- Time: Allows precise timing.
Here are some specific examples of GPS use cases:
- Emergency Response: In the event of an emergency or natural disaster, first responders use GPS to map, track, and forecast weather conditions and track emergency personnel. In the EU and Russia, eCall regulations use GLONASS technology (an alternative to GPS) and telematics to convey data to emergency services in the event of a traffic accident, reducing the time taken to reply.
- Entertainment: GPS can be integrated into games and activities like Pokemon Go and geocaching.
- Health and Fitness: Smartwatches and wearing technology can track physical activity (like running) and compare it to similar demographics.
- Construction, mining, and off-road transportation: From the location of equipment to the measurement and improvement of asset allocation, GPS enables companies to increase the performance of their assets.
- Transport: Logistics companies implement telematics systems to improve productivity and driver safety. The truck tracker can be used to support route optimization, fuel economy, driver safety, and compliance.
How accurate is GPS?
The accuracy of a GPS device depends on many variables, such as the number of available satellites, the ionosphere, the urban environment, etc.
Some factors that can interfere with GPS accuracy include:
- Physical barriers: The time of arrival measurements can distort large masses like mountains, buildings, trees, and more.
- Atmospheric Effects: Ionospheric delays, heavy thunderstorm cover, and solar storms can affect GPS devices.
- Ephemeris: the orbital model inside the satellite could be faulty or obsolete, although it is rare.
- Numerical calculation errors: this can be a factor when the device’s equipment is not designed to specifications.
- Artificial interference: include GPS jammers or counterfeits. Accuracy is generally higher in open spaces without large adjacent buildings that can block signals. This effect is known as the urban cannon. When a device is encompassed by large structures, such as downtown Manhattan or Toronto, the satellite signal is first blocked, then bounces on the building where it finally reads it. This can result in incorrect satellite distance calculations.