3.4. Global Positioning Systems (GPS)

The navigation systems in some form or the other have been in use since the civilizations. Human-beings have always been interested to know where they are, where they are going, and how they are going to get there, and back again to their destination, using some appropriate path.

Since ancient times, humans have been curious about their location and how to reach their destinations. This pursuit of navigation has led to the development of various methods, from simple tools like maps to more advanced systems today. The need to identify our location and navigate effectively has always been essential, whether it was using the stars, landmarks, or eventually, technology.

Think of how people use maps on their phones today. Just as modern apps tell you where to go and how to get there, ancient navigators relied on stars or landmarks to guide them. The quest for pathways and destinations has always been part of human history.

The GPS was developed by the Department of Defence (DoD), USA, which is a part of Global Navigation Satellite System (GNSS), primarily to provide precise estimates of position, velocity and time to the U.S. military. In 1973, the US decided to establish, develop, test, acquire, and deploy a first space-borne GPS, resulting in the NAVSTAR (Navigation Satellite Timing and Ranging) GPS.

The Global Positioning System (GPS) originated from military needs in the early 1970s. The U.S. Department of Defense aimed to create a system that could provide accurate information about position and time. This initiative led to the NAVSTAR system, which has evolved to not only serve military applications but also civilian usage around the world.

Consider GPS akin to a high-tech treasure map. Just as treasure hunters needed precise directions to find their loot, the military needed precision in locating positions to enhance navigation and strategy on the battlefield.

Although the GPS was initially developed for military applications, over a period of time, the civil applications of GPS and GNSS have grown at an alarming rate.

After its military inception, GPS transitioned into civilian life in the 1980s. Its applications skyrocketed, with widespread uses in various fields such as transportation, agriculture, and emergency services. As technology advanced, GPS became integral to daily tasks like navigation and mapping for the average person.

Imagine you are using a GPS app while driving. What started as a tool for military precision now helps millions find their way home, seek out favorite restaurants, or even locate hiking trails right from their smartphones.

The GNSS broadcasts precise, synchronized timing signals to provide precise position, velocity and time. The European Union developed a system, known as GALELIO navigation satellites. Indian system is known as the IRNSS (Indian Regional Navigation Satellite System), using its seven satellites, which will beam accurate navigation signals over India and up to 1,500 km from its borders.

The Global Navigation Satellite Systems (GNSS) encompass various systems that utilize satellites to offer accurate positioning and timing information. These include the United States' GPS, the European Union's Galileo, and India's IRNSS. GNSS works by sending signals from satellites to receivers on the ground, allowing users to pinpoint their locations accurately.

Think of it like a game of catch. If a player throws a ball (the satellite signal) and the receiver catches it (the GNSS device), the time it takes for the ball to travel helps determine the exact distance they are from each other. Similarly, GNSS uses the time between signals and the satellites' locations to calculate precise positioning.

Surveying and mapping fields have greatly benefitted with the availability of GPS and GNSS, such as highways, railroads, mining/geology, agricultural, power, telecommunications, health, law enforcement, emergency, crustal movement, etc.

The application of GNSS in fields such as surveying and mapping has revolutionized the accuracy and efficiency of these practices. Different sectors utilize GNSS technology for tasks including laying out new roads, tracking wildlife, and even in disaster management. With GNSS, data can be collected quickly and accurately, a significant improvement from methods that require extensive manual data collection.

Imagine building a highway. Without GNSS, planners would rely on cumbersome methods that could take weeks to survey the land. With GNSS technology, they can quickly map out the highway path in just a few days, saving time and resources.

Even though GNSS technology provides us greater advantages, but it still has some limitations. Since GNSS satellite signals are too weak as compared to phone signals, they don’t work indoors, underwater, under trees, etc.

While GNSS systems have vastly improved navigation and surveying, they do face limitations, particularly in obstructed environments like buildings, forests, or underwater. The signals emitted by satellites are weak and can easily be blocked or distorted by physical structures. This can hinder accurate readings, causing errors in positioning.

Think of trying to listen to a radio while you're in a tunnel. The signals get blocked, and you can't hear what's being broadcasted clearly. Similarly, if you are indoors or under heavy foliage, GNSS receivers may struggle to get a clear signal, leading to inaccurate location data.

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