Rca1948FrequencyModu.. - The New Jersey Antique Radio Club

64 FREQUENCY MODULATION, Volume Ilation noise. That is to say that when the intelligibility of voice isbeing received through fluctuation noise like tube hiss or thermalagitation, the same intelligibility may be received with 8 decibels morenoise of the triangular characteristic obtained from the output of afrequency-modulation receiver than with the flator rectangular noisecharacteristic obtained from the output of an amplitude-modulationreceiver. This advantage is lost when pre-emphasis and de-emphasisare used because the triangular noise spectrum is converted to arectangular spectrum.