| 摘要 |
PURPOSE:To prevent a tracking error even when the change occurs at the incoming electric wave by providing the difference between the receiving level to start an antenna tracking and the receiving level to stop an antenna tracking. CONSTITUTION:The output of a receiving device 10 is applied through an LPF 2 to an integrator 3, integrated for a constant time while an antenna 11 is standstill, next, sampling-processed 4 and stored 5. An arithmetic processing part 6 calculates the difference of a receiving signal level before and after the antenna is driven, decides the positive and negative and transmits the control signal to a driving device 12. Presently, when the automatic tracking is stopped, a stop level deciding circuit 8 is operated, and the automatic tracking is restarted from the untrackable condition, the difference between the level to restart the tracking and the level to stop the tracking is set larger than the level to descend when the antenna 11 drives by one step, and again, it can be prevented that the antenna 11 is driven to a stop level or below. Even when the change of the incoming electric wave strength is large, the increase in the tracking error can be prevented beforehand.
|
