Typically, the output horn the seeker or ground-based guidance components is an electrical signal that contains information on the direction of the current heading error of the missile and some relative measure of the magnitude of the error. The autopilot converts the Steering error signals into control surface deflection commands (Figure 3) to correct the course of the missile.

The autopilot is a link between the function that indicates a change of heading is needed (guidance processor) and the mechanism that can change the heading (control system). The guidance processor - which may be located on the ground or contained in the seeker signal processor, autopilot, or both-must accurately implement some prescribed guidance law to ensure that the control commands it develops will guide the missile close to the target.

The autopilot may introduce airframe damping to prevent large overshoots in response to maneuver commands or to compensate for dynamic instabilities. It may contain amplifiers, integrators, and mixing circuits that send signals to the proper control surface actuators. In some applications missile maneuver commands may be produced solely on the basis of the seeker output.