There are different kinds of modulation technique based on varying the properties of a pulse train. The Pulse Width Modulation (PWM) varies the width of individual pulses according to the amplitude of the modulating signal. The Pulse Position Modulation (PPM) varies the position of individual pulses from their mean position according to the amplitude of the modulating signal. The PWM is a kind of modulation technique indented for power efficiency, but the power required to transmit individual pulses varies significantly.