Global navigation satellite systems determine position by comparing precisely timed radio signals. Because the signals propagate from known sources and carry timing information, their travel times provide distance-related measurements for trilateration, allowing the system to locate an object relative to a reference frame. This timing-based approach is especially important when direct measurement of position is unavailable.
An inertial navigation system derives motion from accelerometers and gyroscopes rather than relying continuously on external signals. Accelerometers measure changes associated with movement, while gyroscopes track rotation; the system uses these measurements to calculate how an object moves within a reference frame. This makes inertial motion a distinct complement to signal-based positioning.
Triangulation and trilateration use different measured quantities. Triangulation relies on direction, whereas trilateration uses travel-time information to infer distances from signals. Navigation systems may therefore select or combine principles according to which measurements are available. The distinction matters in physics because position depends not only on the measured quantity, but also on the reference frame used to interpret it.
A typical navigation workflow begins by selecting a reference frame, measuring travel time, direction, acceleration, or rotation, and then combining those measurements into an estimate of position and motion. The system can apply error correction after the initial calculation. This sequence links physical observations to a usable path estimate without treating any single measurement as sufficient in every situation.
Combining satellite and inertial measurements can improve accuracy because the two approaches provide different kinds of information. Radio-signal timing supplies externally referenced measurements, while accelerometers and gyroscopes track motion from within the moving system. Their integration is useful when a navigation task requires both an estimate of current position and a continuous account of movement.
In physics, navigation systems provide practical settings for studying reference frames, wave propagation, and motion tracking. Spacecraft guidance, autonomous vehicles, robotics, surveying, and geophysical measurement each apply the same general challenge to different moving or measured objects. The resulting data can describe position, motion, or path, making navigation relevant to both engineered systems and physical observation.