PURPOSE: To simplify structure of steering mechanism by using a repeater synchronous receiver in common with a deviation signal generator in automatic steering.

CONSTITUTION: The transmission system of azimuth signals of a gyro-compass 2 transmits 1X signals to the rotor of a synchronous oscillator 26 for transmitting azimuth signals, i.e. the rotary angle of the gyro-compass 2 is in the ratio of 1:1 to that of the rotor, while in the repeater part the rotor of a synchronous receiver 8 for receiving azimuth signals is connected directly with an azimuth dial and their rotary angles have a relation of 1:1. In case of automatic operation, if an auto- manual turnover switch 27 is turned to the auto-position 27-2, a relay is excied, its contact is connected with a position 28-2, the source of the rotor of the synchronous receiver 8 is cut and the synchronous receiver 8 acts as a synchronous control transformer, which changes into a deviation signal generator. The rotor output is supplied to a deviation signal processing circuit 9 and automatic steering is carried out.