| 摘要 |
PURPOSE:To simplify circuit constitution and reduce multipath distortion securely by using the HPF for impulsive noise detection of an FM receiver equipped with a noise suppressing circuit in common, and rectifying and impressing its output to a tone control circuit. CONSTITUTION:The output of an FM detector 16 is passed through the buffer amplifier 31 of the noise suppressing circuit 30 and then separated to the signal system consisting of an LPF32 and a gate circuit 33 which operate as a delay circuit and a buffer amplifier 34, and the control system consisting of an HPF35, waveform shaping circuit 36, noise control circuit 37, and monostable multivibrator MM38. The HPF35 and circuit 36 detect an impulsive noise and its detection signal is passed through the circuit 37 and triggers the MM38 to generate a pulse with constant width; and the gate 33 is closed to inhibit the impulsive noise from being passed through a stereophonic demodulator 17. The HPF35 is used in common and the output of the circuit 36 is inputted to a multipath distortion reducing circuit 25 to be amplified 23 and rectified 24, and the tone control circuit 21 is controlled by its output to reduce multipath distortion. |
