Abstract: An FM receiver including a noise suppressing circuit in which the signal from which the noise is detected is taken from a front-end section of the receiver and a correction to the noise is made prior to the detector of the receiver. The noise is suppressed by terminating the received signal upon detection of the presence of noise and holding the level which was present before the noise was detected for a predetermined period of time. By detecting the noise in a signal from the front end of the receiver and by making the correction prior to the detector circuit, only a very short predetermined time period need be used and no complicated pilot signal processing circuit is required.

Abstract: A noise eliminating circuit capable of detecting a frequency component largely contained in a pulsive noise from an input signal and cutting off a signal path upon detection of such a frequency component for eliminating the pulsive noise, which circuit is characterized by means for keeping the signal path cut off for the duration when the input signal exceeds a preset level.

Abstract: A noise eliminating circuit comprising means for generating a signal having a phase difference with respect to an input signal, means for simultaneously cutting off the input signal and the phase difference signal at the time when a noise is entering the circuit, means for retaining the levels of the respective signals that have developed immediately before said signals are cut off, and means for outputting a retained signal of one level by adding the same to a retained signal of the other level at a given time constant, thereby to make up for the signal interruption, preventing deterioration in tone quality caused by such signal interruption.

Abstract: A system is provided for developing a gating signal when a radio-frequency signal receiver is tuned to the center-frequency of a selected radio-frequency signal. The system comprises circuit means for tuning the receiver to a plurality of frequencies within a range of frequencies which includes the selected signal and for producing an intermediate frequency signal corresponding to the frequency to which the receiver is tuned. A frequency discriminator is coupled to the circuit means and is tuned to a predetermined frequency, with the frequency discriminator being responsive to the intermediate frequency signal for developing an output signal having a DC component which varies systematically in accordance with the deviation of the intermediate frequency signal from said predetermined frequency.

Abstract: A noise eliminating circuit for detecting and eliminating a noise pulse component included in an amplitude modulated wave, characterized by a circuit arrangement wherein an output of a detector circuit which is adapted to receive an input signal from an IF stage is coupled to an input of a band-pass filter through a noise amplifier; an output of said band-pass filter is coupled to an input of a pulse generator circuit; an output of said pulse generator circuit is connected to a gate circuit for stopping an audio AGC control operation and a gate circuit for eliminating a noise; an output of said noise amplifier is connected to an AGC control circuit through said gate circuit for stopping the audio AGC operation in order to apply an audio AGC control signal to said noise amplifier; and an output of said band-pass filter is connected to said AGC control circuit in order to apply a noise AGC to said noise amplifier; whereby said pulse generator circuit generates a pulse in response to the detection of the noise s