In this blog post, we’ll explore the role GPS plays in our daily lives by examining its principles and various applications.
Bus Information Systems and GPS
Student Cheon Jae-yong takes the bus to school every morning. Until last week, he often found himself waiting at the bus stop for buses with unusually long intervals, idly staring at the cars passing by on the road. However, since getting a new smartphone, he’s been able to use an app to check the estimated arrival time from home and catch the bus right on time. Since the app even tells him when he’ll arrive at his destination, his commute to school has become much more convenient. It looks like he’ll be able to use his time even more efficiently from now on.
This is a common sight in everyday life today. Most public transit users rely on smartphone apps based on the Bus Information System to save time and use the bus more efficiently. It’s a very useful service for busy modern people. So, how is this service made possible?
The Bus Information System is a state-of-the-art transportation system that provides real-time bus operation information; it is a prime example of a civilian application utilizing Global Positioning System (GPS) technology. GPS is a system that allows users to determine their location anywhere in the world by receiving signals transmitted from satellites. However, in actual operation, buses equipped with GPS receivers transmit their location data to a traffic information center via mobile communication networks, and the center analyzes this data to provide the bus’s current location and estimated arrival time to smartphone apps or information displays at bus stops.
The Principle of GPS Positioning
The basic principle of GPS is to calculate the time it took for radio waves to travel by comparing the time information embedded in the signals sent by GPS satellites with the time recorded by the GPS receiver, and then using this to determine the distance between the GPS satellite and the measurement location, thereby determining the position. This method of position determination is called single-point positioning.
Single-point positioning is a method in which a single GPS receiver calculates its own position by receiving signals from multiple GPS satellites. When the cones of three satellites intersect, two intersection points are theoretically formed; however, additional information is required to determine the actual location from among these. Therefore, GPS generally uses signals from four or more satellites to calculate a location. Theoretically, given the condition of the Earth’s surface, a location can be determined using only three satellites; however, in real-world environments, clock errors exist between the GPS satellites and the GPS receiver, so signals from four or more satellites are used to calculate an accurate location. Furthermore, modern positioning technologies utilize signals from multiple Global Navigation Satellite Systems (GNSS), including the U.S. GPS, Russia’s GLONASS, Europe’s Galileo, and China’s BeiDou, in addition to GPS. As a result, the latest smartphones and in-vehicle navigation systems use signals from dozens or more satellites simultaneously to provide highly accurate location information.
Various Applications of GPS
GPS is used in a wide range of fields beyond bus information systems. A prime example is the vehicle navigation system, commonly referred to as a “navigation device.” This system displays the vehicle’s current location and the route to the destination, and guides the driver along the optimal route.
In the surveying field, it is used for precise mapmaking and large-scale civil engineering projects, while in logistics, it tracks the real-time locations of freight trucks to improve transportation efficiency. Furthermore, it plays a crucial role in various other fields, such as supporting rescue operations by quickly pinpointing exact locations in the event of accidents during mountain climbing.
GPS technology has already become deeply embedded in our daily lives, providing a wide range of conveniences. It is utilized as an indispensable core technology in various fields—including bus information systems and vehicle navigation systems, as well as logistics, surveying, and disaster response. Although we often take this technology for granted, a closer look at its principles reveals that it is a sophisticated system combining various cutting-edge technologies. Satellite navigation technology is expected to continue advancing in the future, making our lives even more convenient.
