Pulse time modulation

Pulse time modulation consists essentially of transmitting pulses of constant amplitude and duration, the instantaneous amplitude of the voice being translated into a variation of time intervals of successive pulses, the rate of this variation corresponding to the instantaneous frequency of the signal. The band width required is determined by the steepness of the pulses. The signal/noise ratio obtainable at the terminal of the link increases as the band width increases, so that it is possible to utilize all the frequency band available with advantage. General theory is presented and an explanation is given showing why pulse time modulation improves the signal/noise ratio and how this improvement depends on the frequency band used. The system appears to have far-reaching possibilities in transmission at u.h.f.