GB788544A - Improvements in or relating to transmitting magnetic compass systems - Google Patents

Abstract

788.544. Electric correspondence control. KELVIN & HUGHES, Ltd. Aug. 23, 1955 [Aug. 27, 1954], No. 25006/54. Class 40 (1). A transmitting compass system comprises a magnetic compass needle 9, with a ring 5 of magnetic material mounted in its field so as to be rotatable relative to the compass housing 8 about an axis passing through the needle pivot, means including primary and secondary windings on the ring for generating a voltage dependent on the angular position of the ring relative to said field, means for using this voltage to drive the ring to a fixed position relative to the field and means for transmitting movement of the ring relative to the housing to at least one remote point. The laminated mu-metal ring 5 carries a toroidal primary winding supplied with a 800 c/s. signal from oscillator 15 (Fig. 3) via slip rings 6, and a pair of secondary windings arranged symmetrically at the ends of a ring diameter and connected in series opposition. The resultant 1600 c/s. signal therefrom, depending in phase and amplitude on the sense and magnitude of angular displacement of the ring relative to the field, is supplied through slip rings 6 to an amplifier and phase discriminator 15, the D.C. output of which operates a reversible motor 16 to drive the ring to a null position in the field via flexible cable 17 and the reduction gearing shown. Compass housing 8 is mounted on gimbals in binnacle 20 and the motor 16 is mounted on a balanced bearing 18 pivotally mounted on binnacle platform 19 so that they are both unaffected by motion of the ship. Motion of the ring is communicated to remote points by means of a rotary switch type step-by-step transmitter 26 driven by spur gear 23. Specification 586,506 is referred to.