Distortion and Band-Width Characteristics of Pulse Modulation

Various types of pulse amplitude and pulse time modulated waves have been analyzed by a novel method to determine their exact frequency spectra. Using these results the inherent distortion produced when the audio signal is recovered with a low-pass filter is calculated. The minimum allowable ratio of pulse repetition frequency to maximum audio frequency is expressed in terms of the distortion and the percentage modulation. The form of the result is shown to be common to all types of pulse time modulation. The effects of pulse width, pulse shape, and percentage modulation on the required bandwidth are also discussed.