Determination of the Optimum Modulation Technique for Mobile and Man-packed Military Radio Sets

This study is undertaken to determine whether recent technological progress has resulted in the development of modulation techniques which are superior to frequency modulation for use with mobile or man packed military radio sets. A simplified model of the single channel commun1cation system is developed. In this model the modulation process is considered in two steps. First, some form of speech processing is assumed to be performed. Various types of speech processing considered are clipping, amplitude limiting, filtering, sampling, coding, and vocoding. The second stage of modulation is considered to be the modulation of a radio frequency signal with the output of the speech processor. This model leads logically to a determination of the various possible modulation techniques. Next, performance criteria are developed by considering the requirements of the military communications user and the limitations imposed by the military environment. These considerations result in the selection of spectrum utilization, signal to noise ratio, simplicity of operation, size and weight, reliability and power required as the criteria to be used for the comparison of the various modulation techniques.