GPS, also known as the Global Positioning System is a satellite-based navigation system consisting of at least 24 satellites. GPS works all across the world, independent of the weather conditions, 24 hours a day without any setup charges or subscription fees. Initially, the satellites were put into the orbit by the US Department of Defence for the military purposes. But in the 1980s, they became available to the civilians.

In today’s world, due to the parallel multi-channel design, GPS receivers are highly accurate. As soon as the receivers are turned on, they quickly lock onto the satellites. In urban settings with the buildings or in the dense tree, receivers maintain a tracking lock. The accuracy of the GPS can get affected by certain atmospheric aspects and few error sources. Within the range of 10 metres, GPS receivers are typically accurate. And in fact, accuracy is better in the water.


By using Wide Area Augmentation System (WAAS), the accuracy of some of the GPS receivers is improved. By doing corrections in the atmosphere, the accuracy can be improved in the range of 3 metres. There is no requirement for additional fees or equipment for taking the advantage of the WAAS. Using the Differential GPS or DGPS, the users can get better accuracy.

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The DGPS corrects the GPS distance within the range of 1 to 3 metres. The most common DGPS service is operated by the US Coast Guard. This DGPS correction service has a network that includes the towers to receive the GPS signals and transmit the corrected signals through beacon transmitters.

How GPS works?

In a very precise orbit, GPS satellites take two revolutions around the Earth in a day. A unique signal and an orbital parameter are transmitted by each satellite. Through this, the GPS device decodes and locates the correct location of the satellites. Through this information and trilateration, GPS detects the exact location of the users. The distance to each satellite can be measured through the GPS system. It is measured as per the time a satellite takes to receive the transmitted signal.

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To track your movement and get 2D position, a GPS receiver needs to be locked at least onto 3 satellites. By connecting to the 4 or more satellites, your 3D position can also be determined. Usually, the GPS receiver connects with more than 8 satellites, but it is dependent on your location and the time of the day. There are many devices that can do all this from your wrist.


After determining the position of the user, the GPS unit can calculate the other informations like:

  •         Speed
  •         Track
  •         Bearing
  •         Distance to the destination
  •         Trip distance
  •         Sunrise and sunset time

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