Abstract: A remotely readable fiber optic compass. A sheet polarizer is affixed to a magnet rotatably mounted in a compass body, such that the polarizer rotates with the magnet. The optical axis of the sheet polarizer is preferably aligned with the north-south axis of the magnet. A single excitation light beam is divided into four identical beams, two of which are passed through the sheet polarizer and through two fixed polarizing sheets which have their optical axes at right angles to one another. The angle of the compass magnet with respect to a fixed axis of the compass body can be determined by measuring the ratio of the intensities of the two light beams. The remaining ambiguity as to which of the four possible quadrants the magnet is pointing to is resolved by the second pair of light beams, which are passed through the sheet polarizer at positions which are transected by two semicircular opaque strips formed on the sheet polarizer.

Abstract: The compass repeaters of a gyro-compass are adjusted by a follow-up motor (1) in response to differential signals between the north-indicating gyro-system and a gyro-system enveloping bowl (18) which is connected to the compass card.In order to permit adjustment of the compass repeaters and a consistent verification of the relative positions of the master compass card and the compass repeater cards, an electronic control means (10) produces a pulse sequence for stepping motors which corresponds to the differential signals, the stepping motors (1) synchronously adjust the compass cards of master compass and compass repeaters, a sliding contact (11), comprising an interruption point (5), is in wiping contact with a brush (6), and an adjusting power supply (9) supplies a current to brush (6) for adjusting the compass cards, while the follow-up switch (7) is off, and until the interruption point (5) is contacted by the brush (6).

Abstract: To correct latitude-related errors in the delivery of data from a gyrocompass to an indicator through a synchro transmitter with three-phase Y-connected primary and secondary windings, the synchro transmitter is energized from a single-phase a-c source having one terminal connected to one primary winding and the other terminal connected to the two other primary windings with interposition of a variable resistance in series with one of the two latter windings. These two windings may be interchanged to correct errors of opposite sign.

Abstract: In an azimuth reference system including a flux valve coupled to a synchro stator and a directional gyro having its outer gimbal mechanically coupled to the synchro rotor, a low power electronic slaving circuit having its input electrically coupled to the rotor of the synchro and its output coupled to a torquer for slaving the directional gyro into synchronism with the flux valve. The low power electronic circuit includes a phase compensated amplifier coupled between the synchro rotor and a demodulator for producing a bipolar slaving error signal which is coupled through a high gain amplifier to parallel connected coils in the torquer. A threshold detector circuit responsive to the speed of the gyro rotor controls a limiter feedback circuit in the high gain amplifier thereby limiting its gain when the gyro rotor has attained a predetermined speed.