Dither generation for ring laser gyroscopes

Abstract

A navigation system comprising an RLG (6), means for inducing an oscillatory phase change in the output of the laser of the RLG which simulates an oscillatory dither whose amplitude is in excess of the sum of a defined lock-in range and a defined, narrower control zone, and means (3) for activating said oscillatory dither when the rotation rate applied to said RLG is within said control zone but to apply to the laser output a dither fixed at its full amplitude in the sense of the rotation rate applied to the RLG whenever said rotation rate is outside said defined control zone. Means (9) are preferably provided for applying to the laser output a dither output fixed at its full amplitude in the opposite sense and for the same period as a fixed dither output has previously been applied, provided that the applied rate is not outside said control zone in the original sense. The invention preferably includes means for reinstating oscillatory dither when the applied rate exceeds a higher control rate limit defined in both senses of rotation.

Dependencies are inferred from the claim text.