Tracking radar systems are used to measure the target's relative position in range, azimuth angle, elevation angle, and velocity. Target tracking is important to military radars as well as to most civilian radars. In military radars, tracking is responsible for fire control and missile guidance; in fact, missile guidance is almost impossible without proper target tracking. Angle tracking is concerned with generating continuous measurements of the target's angular position in the azimuth and elevation coordinates. Sequential lobing is one of the first tracking techniques that was utilized by the early generation of radar systems. Sequential lobing is often referred to as lobe switching or sequential switching. Amplitude comparison monopulse tracking is similar to lobing in the sense that four squinted beams are required to measure the target's angular position. The radar continuously compares the amplitudes and phases of all beam returns to sense the amount of target displacement off the tracking axis.