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Start for freeThe Timeless Principle of Triangulation Behind GPS Technology
The Global Positioning System (GPS), a cornerstone of modern navigation, owes its operational principle to a method known as triangulation. This technique, surprisingly, was already in use during ancient times, about 2600 years ago in Greece. Let's delve into how triangulation, an age-old concept, forms the backbone of today's GPS technology.
Understanding Triangulation with a Treasure Hunt
To grasp the concept of triangulation, imagine you're on a treasure hunt. The first clue tells you that the treasure is located 205 km away from Notre-Dame de Paris. This clue alone places the treasure somewhere within a 205km radius circle centered on Notre-Dame. Yet, this information leaves us with numerous possibilities - the treasure could be near Bourges, Lille, Chimay in Belgium, or Caen in Normandy.
The hunt becomes more focused with a second clue: the treasure is also 243 km away from London. Drawing another circle with this radius around London intersects with our first circle in only two places - Lille and near a beach by Caen. However, the pinpoint accuracy we seek still eludes us until we receive a third clue. This clue states that the treasure is 93 km away from Brussels, allowing us to draw a third circle and narrow down the location to Lille.
The Role of Measurement Uncertainty
But what about pinpointing the exact location in Lille? For that, we require measurements accurate to the meter. However, drawing circles based on such precise measurements reveals that they do not intersect at a single point. This discrepancy is due to the uncertainty of measurement, an inherent aspect of all measurements. For example, measuring a distance with a meter rule cannot be more accurate than 0.5 mm due to the spacing of the gradations. In our treasure hunt scenario, considering a distance accuracy of ±50 m allows us to find a common area where the treasure lies, near the main square in Lille.
GPS: Triangulation in the Sky
This treasure hunt analogy mirrors how the GPS functions. Since 1978, the American army has maintained a fleet of satellites that continually send radio signals containing two key pieces of information: the satellite's position and the signal's sending time. GPS devices on Earth, found in cars and smartphones, receive these signals. They calculate the distance from the satellite by determining the time it took for the signal to arrive. Given that radio waves travel at the speed of light, this allows for the calculation of the distance to the satellite.
The Importance of Precision
For accurate GPS location, highly precise clocks are necessary. Even a millionth of a second's error in timing can lead to a 300m discrepancy in location. This is why GPS satellites are equipped with atomic clocks that achieve precision better than a tenth thousandth of a second, enabling location accuracy within 30m. The European Galileo system, expected to be fully operational by 2014, promises clocks 30 times more accurate, potentially allowing for geolocation with up to 1m accuracy.
Conclusion
The principle of triangulation, refined through millennia from the ancient Greeks to today's sophisticated GPS technology, illustrates the remarkable journey of human ingenuity. By understanding the foundations upon which modern navigation systems are built, we gain a deeper appreciation for the tools that guide us through our daily lives and the voyages that lie ahead.
For more insights into the fascinating world of GPS technology and its historical roots, watch the original video here.
