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The Global Positioning System (GPS) and how it works?

The Global Positioning System (GPS) is satellite based navigation system. GPS has revolutionized global navigation. Its usefulness surpassed navigation. As a result, Search and rescue has been improved.

When you last used your phone to ask Google Maps to pinpoint your exact location on a map, did you ever take a moment to think about how GPS systems are able to provide such precise results?

In 1973, the United States Department of Defense was the organization that first introduced the Global Positioning System, now known as GPS (known as NAVSTAR). By 1993, there were 31 GPS satellites in orbit around the Earth, each of which was transmitting orbital and positional data that the military could use for various purposes, including navigation and other military operations.

In the 1980s, data provided by GPS satellites was made available to the public, creating a market for the large variety of GPS navigation systems available today.

Users from both the military and the general public now have access to a comprehensive satellite network thanks to Global Positioning System. Information can be accessed at any time of the day or night. Once upon a time, accuracy was on or around 15 meters, which is approximately 49. By the year 2000, the precision had been improved to a distance of 5 meters, which is approximately 16 feet. The accuracy of a receiver from today that operates on the L5 band can be improved to less than one foot if the receiver is used. It is anticipated that all 31 satellites will be functioning on the L5 band by the year 2027.

USA, Russia, China, Europe, and India all own their own active GPS systems as of the writing of this article. Japan is creating its own GPS system, which is scheduled to go live in 2023.

Let’s take a look at the evolution of GPS, as well as its applications and operational principles.


What is Global Positioning System and why it’s so important?

GPS is essential since it allows you to determine where you are and where you are going when moving from one location to another. Navigation and location are essential yet laborious tasks, which GPS facilitates. Once GPS determines your location, it begins tracking additional data such as speed, bearing, tracks, trip mileage, sunrise/sunset time, and distance to destination, among others. GPS employs “artificial” stars as reference points to calculate positions with an accuracy of a few meters.

However, with modern GPS devices, it is possible to obtain considerably more precise data than centimeter readings. With the help of GPS, it is possible to assign a unique and specific address to every square meter on the earth. Thus, GPS is currently integrated into automobiles, aircraft, boats, construction equipment, smartphones, laptop computers, shoes, and belts. In addition, a GPS tracking system installed in a phone can substantially assist individuals in receiving automated GPS information via their mobile devices.


How GPS works?

Satellite Navigation is based on a global network of satellites in medium earth orbit that transmit radio signals. Users of Satellite Navigation are most familiar with the 31 United States-developed and operated Global Positioning System (GPS) satellites. Three further constellations offer similar services. These constellations and their enhancements are together referred to as Global Navigation Satellite Systems (GNSS). GLONASS, created and operated by the Russian Federation, Galileo, developed and operated by the European Union, and BeiDou, developed and operated by China, are the other constellations. All providers have granted the international community unfettered access to their own platforms. All service providers have established ICAO Standards and Recommended Practices to facilitate the use of these constellations for aviation.

95% of the time, the basic GPS service offers customers with an accuracy of around five meters anywhere on or near the earth’s surface. To achieve this, each of the 31 satellites transmits signals that, when combined with signals from at least four satellites, allow receivers to calculate their location and time. GPS satellites travel around the Earth precisely twice per day. Each satellite emits a unique signal and orbital parameters that GPS devices may decode and use to determine the satellite’s precise location. GPS satellites are equipped with exceptionally accurate atomic clocks. The time information is encoded into the satellite’s transmission codes so that a receiver can continuously detect when the signal was transmitted. The signal comprises data that a receiver uses to compute the satellites’ locations and make other necessary changes for precise positioning.

The time difference between the time of signal reception and the broadcast time is used by the receiver to calculate the distance or range between the receiver and the satellite. The receiver must account for ionosphere and troposphere-induced delays in signal propagation or changes in signal velocity. With knowledge of the distances to three satellites and the satellite’s location at the time the signal was transmitted, the receiver may compute its own three-dimensional position. In order to determine distances from these three signals, a GPS-synchronized atomic clock is required. With distance measurements from a couple additional satellites, the receiver can detect a user’s position and electronically display it, allowing you to measure your running route, map a golf course, or explore any location. Nevertheless, by collecting data from a fourth satellite, the receiver eliminates the necessity for an atomic clock. To calculate latitude, longitude, altitude, and time, the receiver employs four satellites.

Today, GPS is integrated into a wide variety of gadgets, including smartwatches, satellite communicators, autos, boats, and others. A GPS receiver must be locked onto the signal of at least three satellites to determine your 2D position (latitude and longitude) and track your movement. If four or more satellites are visible, the receiver can determine your position in three dimensions (latitude, longitude and altitude). The number of satellites that a GPS receiver can track varies on the time of day and your location on the planet. Some wrist-worn devices can perform all of these functions.

Once your location has been determined, the GPS device can calculate further data, including:

  • Speed
  • Bearing
  • Track
  • Trip distance
  • Distance to destination
  • Sunrise and sunset times
  • And more

Video, how GPS works:

How Does GPS Triangulation Work?


A GPS receiver (such as the one in your phone) receives time stamps from the synchronized clocks on each of the GPS satellites overhead from any location on the earth. The GPS receiver can calculate the distance between where you are standing and each satellite by using the changes in timestamps and the constant speed of light at which radio waves travel.

This informs the GPS receiver of the radius of the spheres with the satellites at the center and your location at the sphere’s edge. Since each satellite travels in a predictable orbit over the world, the GPS receiver may use a recorded almanac of the current known positions of all GPS satellites to approximate where these satellites are over the earth.

With the known position of each satellite and the calculated distance between those satellites and your position, your GPS receiver is able to calculate your approximate location by estimating where the three spheres cross on the Earth’s surface.

The receiver then presents your location on a map.

Using another mathematical theory called as trilateration, GPS receivers require a fourth signal from another GPS satellite to estimate your present altitude on the Earth’s surface.

How Your Mobile Device’s GPS Sensor Operates?

The majority of current cellphones include a GPS receiver chip. This chip is able to receive GPS satellite radio transmissions.

Your phone’s clock is not an atomic clock, so its time is not synchronized with the satellites’ atomic clocks. This is irrelevant, however, when computing location using signals from these satellites.

This is because your phone’s GPS receiver focuses on satellite data and a database of known satellite locations around the Earth. Given that each satellite contains an atomic clock, the time on each satellite is identical at any given time.

Due to the fact that radio signals move at the speed of light and distance from the satellite, the discrepancies between each received timestamp indicates the distance between your phone location and each satellite.

Here’s how GPS navigation works:

  • At 5:12:14 PM, all four satellites communicate the exact same timestamp to your phone.
  • From satellite 1, your phone obtains the timestamp at 5:12:15.
  • Satellite 2 transmits a timestamp of 5:12:16 to it.
  • Finally, at 5:12:17, satellite 3 transmits the timestamp.

This indicates that it takes 1 second for the radio signal from satellite 1 to reach your GPS receiver, 2 seconds from satellite 2, and 3 seconds from satellite 3.

It is a known constant that the speed of light is 299,792,458 meters per second.

The receiver is able to determine, by the use of elementary mathematics, that its distance from satellite 1 is approximately 300 thousand meters, while its distance from satellite 2 is approximately 600 thousand meters, and its distance from satellite 3 is approximately 900 thousand meters.

Your phone’s GPS receiver knows the approximate present location of all three satellites over the earth by using a lookup table from a GPS satellite database, which offers longitude and latitude coordinates for all three.

Your phone may use this information to calculate your own longitude and latitude coordinates on the Earth.

Using your known coordinates, your GPS receiver may calculate your altitude above the Earth by measuring the distance between itself and a fourth satellite.

What are the applications of GPS?

GPS is a powerful and dependable tool for a wide range of enterprises and organizations. Surveyors, scientists, pilots, boat captains, first responders, and mining and agricultural employees are just a few of the people that use GPS for work on a daily basis. They use GPS data to create accurate surveys and maps, to take precise time measurements, to track position or location, and to navigate. GPS is operational at all times and in nearly all weather conditions.

GPS in our everyday life

GPS has five primary applications:

  1. Location — Searching a position
  2. Navigation — Getting from one location to another
  3. Tracking — Monitoring object or personal movement
  4. Mapping — Generating maps
  5. Timing — Making it possible to take precise time measurements.

Some specific GPS use cases are as follows:

Emergency: During an emergency or natural catastrophe, first responders utilize GPS to map, follow and anticipate weather, and keep track of emergency personnel. The eCall rule in the EU and Russia uses GLONASS technology (a GPS alternative) and telematics to convey data to emergency personnel in the event of a vehicle crash, shortening response time. More information about GPS tracking for first responders can be found here.

Entertainment: GPS can be incorporated into games and activities like Pokémon Go and Geocaching.

Health and fitness: Smartwatches and wearable devices can track fitness activity (such as running distance) and compare it to a similar people.

Construction, mining and off-road trucking: GPS enables organizations to maximize the return on their assets by locating equipment, measuring, and improving asset allocation. See our postings on construction vehicle monitoring and off-road equipment tracking for more information.

Transportation: Logistics firms use telematics technology to boost driver productivity and safety. A truck tracking system can help with route optimization, fuel efficiency, driver safety, and compliance.

Agriculture, autonomous vehicles, sales and services, the military, mobile communications, security, and fishing are some of the other businesses that use GPS.

Components of Global Positioning System (GPS)

While the satellite technology on which GPS is based is quite advanced, the system’s operation is surprisingly straightforward.

Any individual GPS navigational system consists of three components.

Satellites: GPS space segment is another name for it. These are the satellites in low-Earth orbit. These spacecraft run on solar energy generated by solar panels. They have backup batteries aboard to keep them running if there is a solar eclipse. The satellite sends out signals to identify its location. The GPS receiver can then determine this information. In a moment, we’ll explain just how.

Command Center: This is what governs the world. Ground antennas and monitoring stations are part of the control segment. These are the things that keep the satellites running. They also monitor the satellite transmissions. They can be found all over the planet.

GPS Receivers: This is the system’s end user segment. A receiver is your phone or another GPS-capable device. If your fishing boat became lost at sea, the Coast Guard would use this information to locate you in an emergency.

In order to determine their own locations, GPS receivers apply a certain type of triangulation, which is a mathematical concept.

GPS Timeline

For thousands of years, humans have practiced navigation by using the sun, moon, stars, and, later, the sextant. GPS was a twentieth-century technological innovation made possible by space-age technology.

GPS technology has been used all around the world throughout history. The launch of Russia’s Sputnik I satellite in 1957 heralded the possibility of geolocation capabilities, and the US Department of Defense quickly began employing it for submarine navigation.

The United States government made GPS public in 1983, but retained control over the available data. It wasn’t until the year 2000 that businesses and the general public acquired full access to GPS, paving the path for increased GPS innovation.

See our post on the History of GPS Satellites and Commercial GPS Tracking for further information on the history and development of GPS.

The major timeline events in the Global Positioning System is here as under: 

  • 1957: The Soviet Union launches the first satellite, Sputnik I.
  • 1959: To keep track of submarines carrying nuclear missiles underwater, the U.S. Navy creates a transit system that uses satellites.
  • 1963: A military study by the Aerospace Corporation outlines the basis for modern GPS systems.
  • 1974: The U.S. launches the first NAVSTAR satellite.
  • 1978: The U.S. starts launching 11 more test satellites for the Block I GPS program.
  • 1983: Korean Air Lines Flight 007 is shot down after making a navigation error, and the U.S. decides to help make air traffic and navigation safer by making GPS available to the public.
  • 1985: Private companies begin making portable GPS receivers for the U.S. government.
  • 1989: While the U.S. launches the first fully operational satellite in the Block II program, Magellan makes the first hand-held GPS device (NAV 1000).
  • 1990: The U.S. Department of Defense creates Selective Availability, which makes GPS readings less accurate for non-military users.
  • 1991: Although not all of the newest satellites are in place, the U.S. uses GPS during the Gulf War.
  • 1995: All 24 GPS satellites become fully operational.
  • 1998: U.S. Vice President Al Gore announces plans for GPS III satellites to do more for civilians, including two additional signals just for aircraft and civilian use.
  • 1999: The first commercial GPS phone is made by Benefon.
  • 2000: The U.S. Department of Defense decides to end Selective Availability. This lets more people use GPS for accurate transport information.
  • 2004: Qualcomm, an electronics company, is the first to put live GPS on a mobile phone.
  • 2005: Civilians get the first GPS channel for their use alone thanks to the new Block IIR satellites.
  • 2010: The U.S. starts launching 12 Block IIF satellites, and the first makes history as the first satellite to get a ride on a modern rocket, or Evolved Expendable Launch Vehicle.
  • 2016: The Block II program, which started in 1989, finishes as the last of the 12 IIF satellites are put in place.
  • 2018: New innovations push the U.S. Air Force to add newer satellites, and the first GPS III satellite successfully launches.
  • 2019: A SpaceX mission takes the next GPS III satellite into space.
  • 2020: Plans to launch another satellite are put on hold because of the COVID-19 pandemic.

How precise is GPS?

GPS device accuracy is affected by a variety of factors, including the number of available satellites, the ionosphere, the metropolitan environment, and others.

Some of the things that can impair GPS accuracy are as follows:

1. Physical impediments: Large masses such as mountains, buildings, trees, and other structures might skew arrival time readings.

2.Atmospheric effects: Ionospheric delays, strong storm cover, and solar storms can all have an impact on GPS equipment.

3. Ephemeris: Although this is becoming increasingly rare, the orbital model within a satellite may be erroneous or out-of-date.

4. Numerical errors: This may occur when the device hardware is not developed to requirements.

5. Atmospheric effects: GPS jamming devices or spoofs are examples of artificial interference.

Accuracy is higher in wide areas with no nearby tall buildings that could obscure signals. This is referred to as an urban canyon. When a device is surrounded by tall buildings, such as in downtown Manhattan or Toronto, the satellite signal is first obstructed before being bounced off a structure and finally read by the device. This can lead to incorrect satellite distance measurements.

Global Navigation Satellite Systems (GNSS)

A GPS is a Global Navigation Satellite System (GNSS), which means that it is a satellite navigation system with global coverage. There are two fully operational global navigation satellite systems as of 2020: the GPS navigation signal timing and ranging (NAVSTAR) system of the United States and Russia’s Global Navigation Satellite System (GLONASS). The NAVSTAR GPS satellite system, which consists of 32 satellites controlled by the United States, is the most well-known and commonly used satellite system. GLONASS is operated by Russia and comprises of 24 operating satellites, with three remaining as spares or in testing.

Other countries are attempting to catch up as well. The European Union, for example, has been working on Galileo, which is anticipated to be fully operational by the end of 2020. China is also developing the BeiDou Navigation Satellite System, which will have 35 satellites in orbit by May 2020. Japan and India, meanwhile, are well on their way with their respective regional systems, the Quasi-Zenith Satellite System (QZSS) and the Indian Regional Navigation Satellite System (IRNSS).

What Exactly Is An Assisted Global Positioning System (GPS)?

Prior to cellphones including GPS technology, individuals would normally utilize handheld GPS receivers that ran on AA batteries. Alternatively, they would install GPS units in cars that were powered by the phone’s battery.

This was due to the increased power required for radio communication. The disadvantage was that you frequently had to wait several minutes for your GPS receiver to “lock onto” enough GPS satellites to calculate your position.

Smartphone manufacturers get past this battery limitation by merging existing cellular triangulation technology. Long before phones had GPS, they could use signals from mobile towers to calculate your position, utilizing the same triangulation timestamp and distance technique as GPS satellites.

Unfortunately, because cell phone towers are located on the ground, this navigational estimate is significantly less precise. As a result, your smartphone GPS software will first use cell signal triangulation to identify your approximate position before updating it once satellite GPS data is available.

Modern smartphones can save battery power by only using GPS data when location updates are required. This is why your location on Google Maps may occasionally jump to a new location as more accurate data becomes available.

GPS in the Future

Countries continue to develop and upgrade their GPS systems. Efforts are being done all across the world to improve accuracy, dependability, and GPS capabilities.

As an example:

  • GNSS receivers are predicted to grow smaller, more accurate, and more efficient, allowing GNSS technology to penetrate even the most cost-sensitive GPS applications.
  • Scientists and rescue personnel are developing novel applications for GPS technology in natural disaster prevention and analysis, such as in the case of an earthquake, volcanic eruption, sinkhole, or avalanche. In order to slow the spread of the COVID-19 pandemic, researchers are considering using smartphone location data to assist with contact tracking.
  • As early as 2023, the launch of new GPS III satellites will improve GPS accuracy to 1-3 meters, improve navigation capabilities, and provide longer-lasting components. By using the L1C civilian signal to communicate with other satellite systems.
  • The next generation of GPS satellites will have improved signal protection, will be less susceptible to signal jamming, and will be more maneuverable to cover dead zones.
  • The National Aeronautics and Space Administration’s (NASA) Long Space Atomic Clock is designed to use a strong onboard GPS satellite to allow future astronauts embarking on deep space trips have better time consistency.

GPS tracking in the future will most likely be significantly more accurate and effective for both personal and commercial purposes.


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