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Global Positioning System (GPS)

Technology | 8-13 yrs | Interactive, Learning Pod

Introduction to Global Positioning System:

The Global Positioning System (GPS) is a space-based satellite navigation system that provides location and time information in all weather, anywhere on or near the Earth. Global Positioning Systems usually refer to the GPS receiver. It was developed by the U.S. military and after a while, the U.S. government opened it up for the public.

The GPS receiver receives signals coming from 27 satellites orbiting the Earth and from those signals the GPS receiver can calculate its absolute position of Earth. These satellites circle the Earth, making two complete rotations everyday. Their orbits are planned in such a way that at any time and anywhere on Earth, there are at least four satellites visible in the sky.

Interesting Facts about GPS:

  • There are only 24 satellites that are operational, the additional 3 are meant for backup in case one of the 24 fails.
  • A GPS receiver locates four or more satellites through signals coming from these satellites which are sent constantly, and then calculates the distance to each of the satellites and from this information calculates its exact position on Earth. This process of pinpointing the location of the GPS receiver is based on the mathematical principal called ‘trilateration.’
  • The signals that the satellites are constantly transmitting are high-frequency, low power radio waves which contain information about the satellite and its location. GPS receivers can calculate the distance to the satellite by the time it takes for the signal to get from the satellite to the receiver.
  • The above mentioned process works well but it has some inaccuracies due to a variety of reasons like signal interference, weather and more. Differential GPS (DGPS) helps correct those inaccuracies. This enhancement is based on stations located on Earth. The hardware at these stations knows exactly where the satellites are, and constantly sends information to GPS receivers (but only to those in which this technology is implemented) to correct their results, thus making it more accurate.
  • Once the GPS receiver makes all the necessary calculations, it can tell the latitude, the longitude and the altitude of its current position. This doesn’t tell much to the average user. So in order to make the use of GPS receiver more user-friendly, many receivers send this data to a program, which displays a map and can show the position on it.
  • Other things that can be determined besides latitude, longitude, and altitude would include things like speed, sunrises and sunsets, bearing, distance and more.

Benefits of GPS :

  • Fuel economy: If you want to maximize your fuel economy you’ll need a good GPS system. Saving money at the pump as well as wear and tear on your vehicle should be one of the main reasons why you should want a good GPS system in your vehicle. Accurate driving directions not only save time, but also helps save a substantial amount of gas money while travelling from place to place.
  • Travel directions: Utilizing a GPS system will give you accurate directions for travel. Whether you are travelling locally, across the country, or globally, you will get accurate directions and constant monitoring of your current position.
  • Recreation: While out on a camp or a hike, a hand held GPS unit will benefit you. Imagine going camping in the middle of the woods and not being able to find your way out. You often hear stories about people that go out camping or hiking and don’t find their way back home. A GPS unit is the answer for these people.
  • Maritime GPS: GPS systems on a ship or a boat help greatly, not only because they tell you where you are located in the middle of the sea, but also because they give you warnings about weather changes; as well as any dangers there might be at sea, like an iceberg, for instance. Another great function of the GPS device used by fishermen is the hotspot finder. A fisherman can relocate a certain spot out at sea by saving his current location, which he may think is ideal for fishing.
  • GPS Tracking: If you run a courier business, rental business, or just plain delivery service, and need to keep track of several vehicles, then GPS is what you need. Keeping track of your vehicles will keep your overheads down. The other end of tracking is keeping track of a family member or child, a GPS tracking system will aid in your efforts.


While there are many benefits from using a GPS device, the U.S. Government controls the export of some civilian receivers. All GPS receivers capable of functioning above 18 kilometers altitude and 515 meters per second are classified as weapons for which export licenses are required. These limits attempt to prevent the use of a receiver in a ballistic missile and other weaponry.

Other Systems :

Other satellite navigation systems which are either in use or under development are:

  1. GLONASS – Russia’s global navigation system. Works worldwide.
  2. Galileo – A global system which is being developed by members of the European Union and other partner countries.
  3. Beidou – China’s own regional navigation system which is limited to Asia and the West Pacific.
  4. COMPASS – China’s global navigation system. Will be operational by the year 2020.
  5. IRNSS – India’s regional navigation system, covering mainland India and the northern parts of the Indian Ocean.
  6. QZSS – Japan’s regional system covering Asia and Oceania.

To get more information about How GPS Works, visit: https://mocomi.com/how-does-gps-works/