Rca1948FrequencyModu.. - The New Jersey Antique Radio Club

28 FREQUENCY MODULATION, Volume Iof a square-wave multivibrator was fed to the input of this radiofrequencyamplifier.In order to make available frequency modulation receivers withdifferent deviation ratios, a method was devised which made possiblethe use of a single intermediate-frequency channel and detection systemfor all receivers. The method consisted in the insertion of a lowpassfilter in the audio output of the receiver so as to reduce the widthof the audio channel and thereby increase the deviation ratio of thereceiver. This procedure is not that which might be normally followedsince to increase the deviation ratio, the audio channel would normallybe left constant and the intermediate-frequency channel increased.