Abstract: A method of determining the difference between the actual rotational speed of the body of a guided missile and a nominal rotational speed is shown to consist of the steps of comparing a shaped output of a Hall effect cell with a shaped output of an oscillator and deriving a signal indicative of any difference between the periods of the shaped outputs.

Abstract: An angle encoder for determining the pitch (or yaw) angle of a gyroscopic mass with respect to the pitch (or yaw) axis of a missile in flight is shown to be the combination of: (a) an optical encoder pattern disposed on the periphery of the gyroscopic mass, such pattern preferably being divided into a substantially equal reflective portion and a nonreflective portion; (b) an optical sensor arrangement having a limited field of view, such arrangement being mounted on the body of the missile to provide a first signal whose level is indicative of the reflective or nonreflective portion in the limited field of view; and (c) circuitry for converting the first signal into a signal indicative of the pitch (or yaw) angle of the missile.

Abstract: An arrangement for determining the rotational position of the rotor of an electrical gyroscope is shown to include:(a) at least one sensor including a Hall effect crystal having a rotating magnetic field applied thereto, such field being synchronous with the field causing rotation of the rotor;(b) a phase-lock loop, responsive to square wave signals corresponding to signals out of the Hall effect crystal and a voltage-controlled oscillator to provide a signal approximating the rotational position of the rotor; and(c) a phase detector, responsive to negative going transitions of the square wave and to reference pulses to synchronize the rotational position of the rotor with the reference pulses.