Impulse noise in narrow-band FM receivers

THE relatively narrow band frequency modulation (FM) communication receivers utilized in mobile communication are subject to interference caused by impulse-type signals received in the antenna. Most of these signals are from automobile ignition systems, from both the vehicle containing the radio and surrounding vehicles. Such impulses are also obtained from a variety of other electrical equipment. These impulses shock-excite the selective circuits in the receiver and produce a transient response from these selective circuits which interferes with the intelligence to be received from the desired information signals.