How do conical scan and monopulse tracking systems work?
============ To perform the angular tracking of a target, it shall be measured how much, and in which direction, the target is away from the radar antenna axis. The first technique used for this purpose was the so-called sequential lobing. In this technique, normally using multiple antenna feeds, the beam was sequentially pointed slightly away, in the 4 directions, from the antenna axis. Comparing the amplitude or right-left and up-down echoes, it was possible to determine the target off-axis in azimuth and elevation. The conical scan is an evolution of this technique, in which the beam is continuosly moved (nutated) around the antenna axis (typically, this is achieved by nutating the feeder, at frequencies in the order of tens of Hz). An echo from an off-axis target will then be amplitude modulated (at the conical scan frequency). The modulation depth provides the error amplitude, while its fase is related to the direction of the deviation. Demodulating the modulation envelope in its
