Abstract: An inertial sensor arrangement comprises a fiber gyro which responds to the horizontal component of the angular rate of the earth. A fiber coil of the fiber gyro is arranged at a positioning frame which is supported for rotation about a vertical axis relative to a housing. The positioning frame can be rotatably adjusted and mechanically locked into three fixed positions. Signals obtained thereby provide a measured value of the angle formed between a reference direction and north. Inclination sensors are provided for determining the inclination of the inertial sensor arrangement. The fiber coil inclusive of the positioning frame and two inclination sensors are mounted at a rigid sensor block which is connected to the housing in heat insulating manner.

Abstract: A tape-suspended meridian gyro has an outer housing, an intermediate housing movably mounted in the outer housing and a gyro having substantially horizontal spin axis. The gyro is suspended by means of a tape within the intermediate housing. A pick-off detects the deflection of a substantially vertical upward axis from its central position. The intermediate housing can be moved by servo motors transversely to the substantially vertical upward axis of the gyro. The servo motors are energized by the pick-off through a controller to damp pendulous oscillations of the tape-suspended gyro.

Abstract: A two-axis platform comprises an azimuth gimbal rotatable about an azimuth axis. In the azimuth gimbal an inner gimbal is mounted about an axis. A two-axis gyro having input axes and a spin axis is located in the inner gimbal. The spin axis is always maintained horizontal by a torquer which is controlled by a level sensor. By the horizontal component of the rotary speed of the earth, which acts on the input axis of the gyro, the spin axis is rotated into North through the torquer. The azimuth angle of the spin axis is measured in a first position for elimination of the influence of gyro drifts including axial mass unbalance. Then, azimuth gimbal and inner gimbal are simultaneously rotated by 180.degree. about their axes. Subsequently, the azimuth angle is measured again, to which the spin axis is adjusted. The middle between these positions provides a North indication compensated for gyro drifts.