Pulssimoduulaatio

Pulssimoduulaatio, or Pulse Modulation in English, is a technique used in telecommunications and signal processing to encode information onto a carrier wave by varying one or more properties of a pulse train. This is in contrast to continuous-wave modulation techniques where a continuous sinusoid is altered. The fundamental idea is to represent the analog signal by a sequence of pulses.

There are several types of pulse modulation. Pulse Amplitude Modulation (PAM) varies the amplitude of the pulses in proportion to the amplitude of the modulating signal. Pulse Width Modulation (PWM) or Pulse Duration Modulation (PDM) alters the duration or width of each pulse according to the signal. Pulse Position Modulation (PPM) changes the position or timing of each pulse relative to its ideal position.

Another important category is Pulse Code Modulation (PCM). In PCM, the analog signal is first sampled at regular intervals. These samples are then quantized, meaning their amplitude is assigned to one of a finite set of discrete levels. Finally, each quantized level is represented by a binary code word. This digital representation makes PCM highly robust against noise and interference, making it a cornerstone of modern digital communication systems, including digital audio and video.

Pulse modulation techniques are widely used in various applications, from transmitting voice signals over telephone lines to controlling power electronics and generating waveforms in digital synthesizers. The choice of modulation scheme depends on factors such as required bandwidth, noise immunity, and system complexity.