Radar is used in a wide variety of applications such as in air traffic control, weather monitoring, accurate ground mapping, and radar astronomy. The basic process is to transmit a signal and then evaluate the return signal. If the signal hits an object it returns to the antenna and then the returned signal can give insight into the velocity and distance of the object. The most commonly transmitted signal used in radar is a chirp, which is basically a pulse in the frequency domain or a sinc in the time domain. A single chirp can be transmitted and the delay between the time of transmission and the time of reception indicates the distance of the object. Another option is to send a sequence of chirps, called a burst. Because of the Doppler effect, if the object is moving the chirps are returned with a different frequency. The amount of change of the chirp frequency is correlated with the speed of the object. A smaller frequency indicates that the object is approaching the antenna, and a larger frequency indicates that the object is moving farther away.

The radar sends out short radio wave pulses at a known frequency. The waves hit the target and echo off of it. The speed of the target Doppler shifts the echo and the same antenna is used to receive the returning signal

In our project, we concentrate on radar applied in an air traffic control (ATC) system. Typical ATC radar consists of an antenna that rotates mechanically sweeping out a complete 360 degrees every 4 to 12 seconds. Generally, Azimuth beam resolution is 1 to 2 degrees and the vertical antenna pattern is a beam ranging from 30 to 45 degrees in angle. When the antenna sweeps by an airplane, there will be a series of hits. Based on the information obtained from these hits, the ATC system must track hundreds of airplanes within its view. This information then goes to the controller. At a major airport, the ATC system consists of technical equipment handled by a team of highly skilled controllers

Controllers in an Air Route Traffic Control Center