GB749012A - Improvements in or relating to navigational instrument systems - Google Patents

Abstract

749,012. Electric indicating systems. SPERRY GYROSCOPE CO., Ltd. May 13, 1954 [May 28, 1953], No. 14874/53. Class 40(1) An alarm is operated according to the magnitude of the lack of correspondence (isogonalisation error) between the indicating elements or shafts driven by two identical navigational instruments. As shown Fig. 1 a system comprising a gyromagnetic compass G1 driving a remote indicator X1 through a known form of transmitter Tl e.g. servo controlled, is duplicated at G2, T2, X2, the isogonalisation error being measured by a mechanical differential 14 which drives an indicator 16 in accordance with the differential displacement of the two transmitter shafts 12, 13. The indicator may operate a visual or audible alarm at some predetermined error value. The differential may, alternatively be electrical and fed from synchro devices driven by the respective transmitters, Fig. 1A (not shown). In another embodiment, Fig. 2, the isogonalisation error is indicated by a synchro system, the transmitter rotor R1 of which is driven by the transmitter T1 and energized from a source 24. The stators S1, S2 are coupled in the usual way and the receiver rotor R2, driven by the transmitter T2, is mounted on its shaft at right angles to the rotor R1-when the error is zero-so that a centre zero instrument 25 connected to the rotor R2 will indicate the magnitude and sense of the error. This error detecting arrangement may be actuated from the remote indicators X1, X2 instead of the transmitter T1, T2 Fig. 3 (not shown) and in either case, instead of mounting the rotors R1, R2 at right angles, they may be mounted parallel to each other and the necessary 90 degree phase displacement effected by:- (a) a differential synchro connected between the stators S1, S2 Fig. 4 (not shown), (b) an autotransformer connected between the stators Fig. 5 (not shown), (c) using resolver type synchros and cross connecting the stators thereof, Fig. 6 (not shown), (d) using synchros having two rotor windings mounted at right angles, Fig. 7 (not shown).