G01C—MEASURING DISTANCES, LEVELS OR BEARINGS; SURVEYING; NAVIGATION; GYROSCOPIC INSTRUMENTS; PHOTOGRAMMETRY OR VIDEOGRAMMETRY
G01C19/00—Gyroscopes; Turn-sensitive devices using vibrating masses; Turn-sensitive devices without moving masses; Measuring angular rate using gyroscopic effects
G01C19/02—Rotary gyroscopes
G01C19/34—Rotary gyroscopes for indicating a direction in the horizontal plane, e.g. directional gyroscopes
G01C19/36—Rotary gyroscopes for indicating a direction in the horizontal plane, e.g. directional gyroscopes with north-seeking action by magnetic means, e.g. gyromagnetic compasses
G—PHYSICS
G01—MEASURING; TESTING
G01C—MEASURING DISTANCES, LEVELS OR BEARINGS; SURVEYING; NAVIGATION; GYROSCOPIC INSTRUMENTS; PHOTOGRAMMETRY OR VIDEOGRAMMETRY
G01C19/00—Gyroscopes; Turn-sensitive devices using vibrating masses; Turn-sensitive devices without moving masses; Measuring angular rate using gyroscopic effects
G01C19/02—Rotary gyroscopes
G01C19/40—Rotary gyroscopes for control by signals from a master compass, i.e. repeater compasses