Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
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
G01C19/38—Rotary gyroscopes for indicating a direction in the horizontal plane, e.g. directional gyroscopes with north-seeking action by other than magnetic means, e.g. gyrocompasses using earth's rotation