| 摘要 |
PURPOSE:To enable to automatically restore the control system from open to closed loop, by detecting the level of the input pilot signal of the variable gain control circuit with the selection circuit when the level of the pilot signal is in failure. CONSTITUTION:The level of the pilot signal picked up from the variable gain circuit 12 is fed to the circuit 12 via the memory circuit 21 to control the gain of the circuit 12. Further, the pilot level detection circuit 17 detects the level of the pilot signal of the output of the circuit 12 when the level of the pilot signal is normal and within the predetermined range, and detects the level of the input pilot signal of the circuit 12 with the selection circuit 26 when the level of the pilot signal is not normal and out of the predetermined range. Thus, when the pilot signal is restored from abnormal to normal level, only the level of the input pilot signal can automatically restore the control system from open to closed loop. |
