The recent development of decimetric and centimetric valves for radiolocation purposes has stimulated interest in the possibility of extending pulse techniques to communication applications. In the design of pulse communication systems a knowledge of the carrier and sideband frequency structure of modulated recurrent pulses of different types is necessary to complete the information presented by a direct inspection of the time waveforms themselves. Not only is any relative distortion between the fundamental modulating tones of interest but also the degree of intermodulation between them when the pulses are demodulated.