| 摘要 |
PURPOSE:To reduce distortion, crosstalk, etc., with simple circuit constitution by applying a local oscillation signal, having the same frequency with a received frequency signal, to a detecting circuit for detection. CONSTITUTION:A high-frequency signal received by an antenna 11 is applied to a high-frequency amplifying circuit 12, and the output signal of this amplifying circuit 12 and the oscillation signal of a local oscillating circuit 14 are both applied to a detecting circuit 13 for detection to be converted into a low-frequency signal, which is passed through a low-pass filter 15 to eliminate unnecessary components. Then, the resulting signal is amplified by a low-frequency amplifying circuit 16 to operate a speaker 17. Consequently, even if a small signal is applied to the detecting circuit 13, sufficient detection is performed by applying the oscillation signal from the local oscillating circuit 14 to the detecting circuit 13 without the great amplification of the amplifier of the amplifier 12 like a straight type receiver. |
