Normalized Power Spectra for FDM/FM Signals and Noise Power Ratio Calculations

By using normalized power spectra to represent frequency division multiplex/frequency modulation (FDM/FM) signals, the noise-power ratio (NPR) resulting from interference between FM signals can be easily calculated. These non-Gaussian power spectra are shown for CCIR preemphasis, rms frequency modulation (
m
) indexes from 0.1 to 1.2 and for top-to-bottom baseband frequency ratios (
b
) from 2 to 20. Proof is given that signals with the same
m
index,
b
ratio, and preemphasis characteristics will have the same power spectrum. Also given is the value of the index
m
for a given
b
ratio that can be used to represent the FDM/FM signals by a Gaussian power spectrum.