trilaterering

Trilaterering is a positioning technique used to determine an object's absolute location in three-dimensional space. It relies on measuring the distance from the object to three known points, often called reference points or anchors. Each distance measurement defines a sphere, with the object located somewhere on the surface of that sphere. The intersection of these three spheres will yield a maximum of two possible points where the object could be.

To uniquely determine the object's position, a fourth distance measurement to a fourth reference point is typically required. This fourth sphere will intersect the previous two intersection points at only one location, thus pinpointing the object. The principle is based on geometric intersections. The accuracy of trilaterering depends on the precision of the distance measurements and the geometric arrangement of the reference points. If the reference points are too close together, the intersection of the spheres can be highly sensitive to small errors, leading to a less accurate result. Conversely, widely spaced reference points generally improve accuracy.

Trilaterering is fundamental to many modern navigation and positioning systems, most notably the Global Positioning System (GPS). In GPS, the reference points are satellites orbiting the Earth, and the distances are calculated by measuring the time it takes for radio signals to travel from the satellites to a receiver. Other applications include surveying, robotics, and underwater navigation.