Rca1948FrequencyModu.. - The New Jersey Antique Radio Club

SERVICE RANGE OF FREQUENCY MODULATION 219of the energies passed by the two spectrums; the root-mean-squarevoltage ratio is the square-root of this area ratio. The correspondingcomparison for impulse noise may be calculated by comparing theareas of the spectrums. The ratio of the areas of the spectrums givesthe peak voltage ratio directly for impulse noise. These areas may beobtained by integration or they may be plotted and a planimeter used.The curves of Figure 6 show the results of such a determination bythe use of integration. These curves give the signal-noise ratio gaineffected by the de-emphasis circuit alone. To obtain the overall gaindue to pre-emphasis, the transmitter loss of 2.5 decibels must be subtractedfrom the values indicated by the curves.—r44