Attitude control system for mobile antenna

Abstract

The attitude of an antenna which is used with an artificial satellite emitting a radio wave is controlled by a combination of the establishment of an antenna attitude in accordance with gyro data, a small range conical scan which is conducted when a reception level is less than a first reference and at or above a second reference and is relatively high for altering the antenna attitude to a direction which provides a higher reception level, and a broader range search scan which is conducted when the reception level is less than the second reference and is relatively low for altering the antenna attitude to a direction which provides a higher reception level. In one manner, in order to reduce an antenna driving time, an antenna attitude is regarded as an optimum if a fluctuation which occurs in the reception level during the small range conical scan is small, and the first reference is updated to a value which is slightly less than a maximum value in the reception levels which are obtained during the conical scan. In second manner, the first reference is a fixed value, and as long as the reception level continuously remains at or above a given value, which may be the first reference, for example, gyro data is initialized at a given time interval in order to prevent an accumulated error in gyro data from increasing. In other words, data representing a start point and a variance from the start point are cleared.