Pulse Position Modulation (PPM) is a pulse modulation technique that uses pulses that are of uniform height and width but displaced in time from some base position according to the amplitude of the signal at the instant of sampling. Pulse position modulation is also sometimes known as pulse-phase modulation. Pulse position modulation has the advantage over pulse amplitude modulation (PAM) and pulse duration modulation (PDM) in that it has a higher noise immunity since all the receiver needs to do is detect the presence of a pulse at the correct time; the duration and amplitude of the pulse are not important