Radar
Automotive radar emits radio waves and analyzes their reflections to estimate the range, relative speed, and direction of objects. Radar sensors are widely used for adaptive cruise control, collision assistance, blind-spot monitoring, and parking functions.
What it does
The sensor measures signal delay for distance and Doppler shift for relative speed. Antenna and processing design help estimate angle and separate multiple targets. Radar often works in darkness and can remain useful in some weather where a camera struggles, but software still has to interpret the reflections and may combine them with other sensors.
Resolution, field of view, and range vary by sensor. Metal structures, barriers, road surfaces, multipath reflections, interference, sensor obstruction, heavy precipitation, and unusual targets can create false, merged, or missed detections. Radar does not necessarily identify an object’s visual class by itself.
For frequency bands, antenna designs, signal processing, and sensor fusion, see Automotive Radar Sensors.