Computation of FM distortion in linear networks for bandlimited periodic signals

Computations of the distortion generated in passing large-index, frequency-modulated signals through symmetrical single-pole and three-pole bandpass filters are presented. The computation is for a bandlimited periodic modulation signal; noise modulation is simulated by the use of periodic noise samples in a Monte Carlo procedure. The convergence of the Monte Carlo procedure is illustrated for the case of the single-pole filter and the results are in good agreement with measurements. Computations of envelope distortion are also presented. These data give the amplitude-to-phase conversion in the receiver containing the filter to within a constant factor, the constant being the AM/PM conversion coefficient of the limiter.