In radar systems, what does the term 'Doppler effect' refer to?

The term 'Doppler effect' in radar systems refers to the change in frequency of radar waves due to the movement of a target in relation to the radar source. When a radar signal is transmitted towards a moving object, if that object is moving toward the radar, the frequency of the returned signal is higher than the transmitted frequency; conversely, if the object is moving away, the returned frequency is lower. This change in frequency allows radar systems to determine the speed and direction of moving targets, which is crucial in various applications such as traffic monitoring, aviation, meteorology, and military operations, where understanding the velocity of objects is essential. This concept is fundamental in enabling radar systems to perform speed measurements and enhance target tracking accuracy.