| 摘要 |
PURPOSE:To make stable receiving possible even if a receiver unprocessed for intermodulation interference and multipath interference is used, by connecting the system output to the antenna terminal of the receiver simply. CONSTITUTION:The receiving signal dependent upon receiving part 1 is applied to low-noise high-frequency amplifying circuit 3 through matching circuit 2 for impedance matching. This circuit 3 is constituted with the amplifier of a low-noise factor. The amplification output is mixed with the local oscillation signal of a prescribed frequency from local oscillation signal generating circuit 5 by mixing circuit 4. Band pass filter 6 is provided which leads out selectively only the prescribed- frequency signal from this mixed output. This frequency-converted output becomes an unbalanced output due to impedance converting circuit 7. By the variable operation of the signal frequency of local oscillation signal generating circuit 5, namely, the tuning operation, impedances and frequency selection characteristics of circuits 2 and 3 are interlocked with each other and are controlled variably. |
