Command guidance is similar to beam riding in that the target is tracked
by an external radar. However, a second radar also tracks the missile
itself. The tracking data from both radars are fed into a ground based
computer that calculates the paths of the two vehicles.
This computer also determines what commands need to be sent to the
missile control surfaces to steer the missile on an intercept course with
the target. These commands are transmitted to a receiver on the missile
allowing the missile to adjust its course. An example of command guidance is
the Russian SA-2 surface-to-air missile used against US aircraft in North
Also note that command guidance is not limited just to radar. Another
method that falls under command guidance is the use of wire guided systems.
In this technique, commands are sent to the missile through a conventional
wire or fiber optic cable that reels out from the missile back to its
launcher. Wire guidance is often used on anti-tank missiles like TOW, which
can be launched from both ground vehicles and helicopters. Many naval
torpedoes fired from submarines also use wire guidance.