| 摘要 |
PURPOSE:To prevent a level of other reception signal from being exceeded due to the level reduction of a pilot signal by using a branch circuit so as to branch part of the reception signal outputted to a demodulator of the post- stage, applying level control to the branched output by a level control means and inputting the result. CONSTITUTION:A pilot level detector 5 is a narrow band detector in a receiver installed in the satellite communication earth station employing the SCPC system, only a pilot signal in an output signal of a variable attenuator 3 is detected and the detection output is digitized by an A/D converter 6 and inputted to a control circuit 7. The control circuit 7 compares the digital value with a reference value and since the attenuation of the variable attenuator 3 is controlled by an analog signal in a direction where the error is decrease, the level of the pilot signal given to a pilot frequency detector 4 is nearly kept constant. The control circuit 7 detects whether or not the error is within a prescribed range and if the error is deviated from the prescribed range, it is discriminated that the pilot signal reception is interrupted. |
