Ranging

Ranging is the process of determining the distance to a target or reference point. It is used across disciplines, including surveying, navigation, robotics, astronomy, and ecology, to establish spatial relationships and to support positioning, mapping, and tracking tasks.

There are several broad approaches to ranging. Direct measurement in surveying uses tapes, chains, or electronic distance measurement devices to obtain a physical distance. In many modern systems, ranging relies on signal transit time or phase information. Time-of-flight methods measure how long a signal takes to travel from a transmitter to a target and back, multiplying the travel time by the known speed of the signal (such as light in radar, lidar, or laser ranging; or sound in sonar). Phase-based ranging estimates distance from the phase difference between transmitted and received continuous signals. Trilateration and multilateration determine the position of a target by combining distance measurements from multiple known references. Global navigation satellite systems typically use pseudorange measurements that combine signal travel time with clock biases to compute position.

Ranging serves a variety of applications. In surveying and geodesy, it helps create accurate maps and control networks. In navigation and wireless localization, ranging underpins positioning services and distance-based routing. In astronomy and space exploration, ranging techniques like lunar laser ranging measure distances to celestial bodies to test physics and refine orbital models. In ecology, ranging concepts are used to estimate the home or foraging range of animals through tracking data.

Accuracy depends on signal speed, measurement precision, and environmental factors such as atmosphere, multipath reflections, and clock stability. Each method balances cost, speed, and precision for its intended context.