Direction errors - compensation device, for example for target tracking antennas

摘要

A pointing error compensating device for compensating the error induced in a position indicator as a result of forces acting on a structure, such as gravitational forces acting on a large antenna having a reflecting dish, that is pivotal about an elevation axis.P PThe error compensating device comprises a torque producing device having a moment arm in the form of an eccentric mass attached to a shaft coupled to the structure, the shaft being rotatable in response to a pivotal movement of the structure. The shaft is also coupled to a drive shaft of the position indicator. The eccentric mass is attached to the transmission shaft in such a manner that it applies a torque to the latter which is proportional to the cosine of the angular orientation of the structure about the elevation axis. The transmission shaft is deflected torsionally by the eccentric mass in an amount which is designed to be approximately equal and opposite to the error which otherwise would be induced into the position indicator.