Abstract: Azimuth and elevation information relating to ground based weapons equipment is inputted to a north finding system. The system determines angular azimuth and elevation errors and transmits signals to a display arrangement for indicating the direction to rotate the system so as to eliminate the errors. As the system is aimed, a gyro included in the north finding system measures angular rotation about its input axis and accelerometers measure the change in tilt. The computer projects the rotations to the horizontal plane and determines the change in azimuth. This is a continuous procedure until all errors are eliminated.

Abstract: A gyrocompassing system intended for land based equipment requiring north reference information includes a novel gyrocompass implementation which enables utilization of high grade inertial sensors while achieving the desired goal of moderate cost. The north finding system is designed to provide high accuracy with fast reaction time over a wide temperature range without the aid of heaters and other auxilliary equipment. The arrangement is specifically configured to tolerate settling and/or oscillatory base motion without additional reaction time or degradation of gyrocompassing accuracy.

Abstract: A gyroscope with a solid rotor synchronous motor having three-phase square wave supply voltage is provided, and control circuitry including logic circuit components for periodically producing an amplitude modulation in the motor excitation voltage of constant frequency that results in a periodic slipping of a few degrees of the solid rotor relative to the electrical field is provided, whereby gyro drift errors varying sinusoidally in sense and magnitude in accordance with the relative rotation between field and rotor, balance out during each complete cycle of relative rotation.

Abstract: In order to correct errors in a synchro control transmitter, the error in the transmitter is measured at equal angular increments, the magnitude and phase of the maximum error of the second harmonic determined and resistors placed across two pairs of the three transmitter outputs selected such as to establish a second harmonic load unbalance which is approximately equal in magnitude and opposite in phase to the measured error.