| 摘要 |
PURPOSE:To radiate an interfering radio wave by oscillation and prevent obstacle from occurring by detecting a signal error ratio and decreasing the gain of an amplifier when the signal error ratio exceeds a prescribed value. CONSTITUTION:A received signal received by a receiving antenna 101 is inputted to an attenuator 102, an attenuator 201, a phase shifter 202, and an amplifier 103, and the signal after being amplified by the amplifier 103 is sent by a transmitting antenna 104. The amplified signal is branched and inputted to a receiver 204 after its gain is adjusted by an attenuator 207, so that the signal is demodulated. The demodulation output of this receiver 204 is inputted to a signal error ratio detector 205, which detects the signal error ratio. A controller 206 controls the attenuation quantity of an attenuator 201 on the basis of the output of the signal error rate detector 205 and adjusts an attenuation quantity inserted into a loop. Namely, when the signal error ratio exceeds the prescribed value, oscillation is predicted, so the attenuator 201 attenuates the loop gain at a certain value in this case. |
