| 摘要 |
PURPOSE:To accurately detect interference electromagnetic waves and to control the gain of an antenna input according to the input of the interference electromagnetic waves, by keeping an AGC circuit off during the processing of a specified retrieval operation, through the provision of a switch for the AGC circuit and the control of the switch with a controller. CONSTITUTION:A computer system is jointly used for a radio receiver, an output of a mixer circuit 5 is applied to an AGC level detecting circuit 7 and also to an FM demodulator 9. A part of the output of the demodulator 9 is applied to a controller 11, a specified operation is executed at the device 11 with an instruction from an operation key 13 to control a gain controlling means 14 and a local oscillating circuit 6. A voltage in response to the input level detected at the circuit 7 is inputted to a switch 27, and the output of the switch 27 is applied to a high-frequency amplifier circuit 3 to control the gain. The control of the switch 27 is controlled from the result of operation of the device 11 and the switch 27 is controlled according to the input of interference electromagnetic waves. |
