Simplified roll stabilization for directional gyro

Claim 1

IN COMBINATION WITH A DIRECTIONAL GYROSCOPE HAVING A FIRST GIMBAL FRAME ADAPTED TO BE MOUNTED ON A VEHICLE FOR ANGULAR DISPLACEMENT ABOUT A FIRST AXIS FIXED WITH RESPECT TO THE VEHICLE AND CONSTITUTING THE AZIMUTH AXIS OF THE GYROSCOPE, A SECOND GIMBAL FRAME MOUNTED ON SAID FIRST GIMBAL FRAME FOR ANGULAR DISPLACEMENT RELATIVE THERETO ABOUT A SECOND GYROSOCPE AXIS NORMAL TO SAID FIRST AXIS, AND A MOMENTUM WHEEL MOUNTED BY SAID GIMBLA FRAMES FOR ROTATION ABOUT A THIRD GYROSCOPE AXIS PERPENDICULAR TO THE PLANE DEFINED BY SAID FIRST AND SECOND AXES, A SYSTEM FOR DERIVING, FROM ANGULAR DISPLACEMENT OF SAID FIRST GIMBAL FROM A REFERENCE POINT ABOUT SAID FIRST AXIS, A SIGNAL REPRESENTIVE OF THE DEGREE OF SAID DISPLACEMENT IN A HORIZONTAL PLANE, SAID SYSTEM INCLUDING MEANS FOR COMPENSATING FOR ANGULAR DISPLACEMENT OF SAID FIRST AXIS FROM VERTICAL ABOUT A ROLL AXIS PERPENDICULAR TO SAI FIRST AXIS, SAID SYSTEM COMPRISING: MEANS, INCLUDING A RESOLVER CONNECTED TO SAID FIRST GIMBAL TO DETECT ANGULAR DISPLACEMENT THEREOF, TO GENERATE A FIRST ELECTRICAL SIGNAL PROPORTIONAL TO THE PRODUCT OF THE COSINE OF THE ANGLE OF DISPLACEMENT OF SAID FIRST AXIS ABOUT SAID ROLL AXIS AND THE COSINE OF THE ANGLE OF DISPLACEMENT OF SAID FIRST GIMBAL FRAME FROM SAID REFERENCE POINT ABOUT SAID FIRST AXIS AND A SECOND ELECTRICAL SIGNAL PROPORTIONAL TO THE SINE OF SAID ANGLE OF DISPLACEMENT OF SAID FIRST GIMBAL FRAME; AND MEANS, INCLUDING AN ADDITIONAL RESOLVER HAVING A ROTOR AND TWO INPUT WINDINGS, SAID INPUT WINDINGS RECEIVING SAID FIRST AND SECOND SIGNALS, RESPECTIVELY, TO GENERATE A SIGNAL REPRESENTING THE DEGREE OF ANGULAR DISPLACEMENT OF SAID FIRST GIMBAL FRAME ABOUT A VERTICAL AXIS.