Abstract: A pulse noise suppressing system for an FM receiver which includes extracting a noise component from an FM detection signal; amplifying the noise component extracted with a gain that is controlled by an automatic gain control signal corresponding to a level of the amplified component; and providing an off control signal which is triggered when the level of the amplified component is higher than a predetermined level, the off control signal being used to interrupt the transmission of an FM detection signal to a following stage, thereby suppressing a pulse noise included in the FM detection signal. The predetermined level at which the off control signal is triggered is changed in accordance with the automatic gain control signal, or in accordance with a level detection signal corresponding to a level of a received signal.

Abstract: An adjacent channel interference suppressing system for an FM receiver which includes a first detecting device for amplifying and demodulating an intermediate frequency signal which has passed through a wide-band filter; a second detecting device for amplifying and demodulating an intermediate frequency signal which has passed through a narrow-band filter; a level adjusting device for receiving FM detection signals from the first and second detecting devices, and for complementarily and continuously adjusting the levels of the FM detection signals; and a control signal generating device for generating a control signal for controlling the level adjusting device according to the presence or absence of an adjacent channel interference.

Abstract: A space diversity system capable of operating accurately over a wide range of received input electric field strengths. With a middle or high received electric field strength, a search operation for the antenna with the highest strength is commenced in response to noise detected in the output of the antenna presently selected. With a low received electric field strength, the search operation is carried out in response to noise such as white noise at all times.

Abstract: An FM receiver including a noise pulse detection circuit which receives an FM detected signal containing a pilot signal and produces a control signal when a noise pulse is detected. A gate is operable to interrupt the transmission of the FM detected signal to the subsequent stage for the duration of the presence of the noise pulse responsive to the control signal and a holding circuit holds the FM detected signal of the level immediately before the interrupting operation of the gate. A multiplex demodulator receives outputs of the gate and the holding circuit for demodulating an applied FM detected signal. A signal generator is provided in the multiplex demodulator for generating a signal whose frequency and phase are same as those of the pilot signal. A superimposing circuit superimposes a signal obtained from the signal generator on the output of the holding circuit for the duration of the presence of the noise pulse.