GB667354A - Compass system - Google Patents

Abstract

667,354. Indicating direction of magnetic adds. BENDIX AVIATION CORPORATION. June 5, 1950. [July 1, 1949] No. 14017/50. Class 40 (i). A flux-gate compass 1 is energized from a source 17, 19 of relatively high frequency e.g.. 5 kc/s, and is coupled to a receiver 3 whose rotor, when not in the plane of the resultant field, generates a signal of double the frequency of 17, 19 ; this signal is applied to a phase-sensing circuit 27 so that an output is obtained dependent on the phase relationship between the signal and an oscillation of the double frequency from 51 ; this output controls a motor 75 to return the rotor 15 to the plane of the resultant field, the motor being fed with relatively low frequency e.g. 400 c/s. The phase-sensing circuit 27 is preferably as disclosed in Specification 684,955, [Group XL (c)]. The output is applied to a magnetic amplifier 63 so that according to the phasesense of oscillations from 15, current flows through one or other of saturating windings 65 to permit one or other of secondary windings 69, 71 to supply winding 73 of motor 75 and operate motor 75 in the appropriate direction. A filter 23 removes unwanted oscillations from the output of rotor 15, and a similar filter may be employed with the output of the frequency doubler 51.