| 摘要 |
PURPOSE:To reduce the interference disturbance to a receiver of a base station by providing a detector for receiving input and a variable attenuator to a mobile communication system, and decreasing the local oscillating level at the boundary of a strong electric field. CONSTITUTION:An input from an antenna terminal 1 passes through a BPF17, RF amplifier 18, frequency converter 19, IF amplifier 20, demodulator 21 and an AF amplifier and is outputted from a terminal 23. The variable attenuator 24 is connected to power amplifiers 15, 16 of a local frequency. The variable attenuator 24 is controlled by a control circuit 28 receiving a compared output comparing a detected level of an IF level detector 25 with a reference value 27 at an error amplifier 26. Thus, when an output of the IF level detector 25 is large, the local oscillating level is decreased. Thus, the local oscillation of the mobile station at a strong electric field is prevented from giving interruption disturbance to the receiver of the base station. |
