| 摘要 |
PURPOSE:To avoid the leakage of a transmission base band signal from being caused, by driving a variable attenuator and a variable phase shifter with a control circuit and controlling a synthesizer so as to make the transmission base band signal and a pilot signal to zero. CONSTITUTION:A signal from a demolduator 17 and a signal from a variable attenuator are synthesized at the synthesizer 14, the pilot frequency is extracted at a band pass filter 18, and the variable phase shifter 21 and the variable attenuator 22 are driven with a control circuit 20 to make the pilot signal to zero. The pilot signal is canceled at the synthesizer 14 through the operation as mentioned above. Thus, the transmission base band signal synthesized at the pilot signal is canceled the same as the pilot signal at the synthesizer 14, only the received base band signal is outputted at an output terminal 2, and no signal except the received base band signal is outputted at the output terminal 2. |
