Radar, the transliteration of English radar, comes from the abbreviation of Radiodetion Andranging, which means "radiodetectionandranging", that is, the target is found by radio and its spatial position is determined.
Therefore, radar is also called "radio positioning". Radar is an electronic device that uses electromagnetic waves to detect targets.
The radar emits electromagnetic waves to illuminate the target and receives its echoes, thus obtaining information such as the distance from the target to the electromagnetic wave emission point, the rate of change of distance (radial speed), azimuth, altitude and so on.