Two-position north-finding system based on fiber-optic gyroscope can be designed with strapdown style

which has the merits of quick finding and compact structure.Two fiber-optic gyroscopes with approximate scale factors are used and placed on the indexing mechanism with sensing axis maintaining vertical.The mechanism is driven by stepper motor to realize two-position changing.The reducer output shaft and revolving shaft of inertia measurement element holder composed inward-outward coaxial driving form

which is propitious to quick and accurate rotation for compact and high stiffness properties.DSP is used as the core processor of hardware for data acquisition of fiber-optic gyroscopes and accelerometers

and for north-finding resolve.Prototype instrument is built and tests of indexing

single-station repeatability and peripheral precision are done.The test results show that indexing precision is 30″

single-station repeatability and peripheral precision is less than 0.1°

the time of north-finding is less than 3 min and meet the anticipated design target.