Pulse demodulator

(electronics) A device that recovers the modulating signal from a pulse-modulated wave.

A device that recovers the modulating signal from a pulse-modulated wave. This recovery may or may not require a two-stage demodulation. Pulse-duration-modulated (PDM) or pulse-amplitude-modulated (PAM) signals may be completely recovered by a conventional detector in amplitude-modulation (AM) radio or a phase-quadrature-type demodulator in frequency-modulation (FM) radio. The reason is that the pulse area is proportional to the modulating-signal amplitude at the time of each pulse, and the low-pass demodulator output filter removes the pulse-frequency components as well as the carrier-frequency components and leaves only the original modulating-frequency components in the filter output. See also Amplitude-modulation detector; Frequency-modulation detector.

Pulse-position-modulated (PPM) and pulse-code-modulated (PCM) signals require a two-stage demodulation because the pulse train must be processed before the original modulation can be recovered. The pulse-train modulation may be recovered from a radio-frequency (rf) carrier by any appropriate AM or FM detector, provided that the low-pass filter in the detector output passes the significant frequency components of the pulse. See also Pulse modulation.