dimodulasi

Dimodulasi, or modulation in the context of signal processing and communications, refers to the intentional alteration of a carrier signal in accordance with an information-bearing signal. The primary objective of dimodulasi is to enable the efficient transmission of data over a medium by embedding the desired information onto a higher‑frequency carrier that is better suited for propagation.

In practice, dimodulasi can be realized through changes in the amplitude, frequency, phase, or a combination of these characteristics of the carrier. The most common categories are amplitude modulation (AM), frequency modulation (FM), and phase modulation (PM). In amplitude modulation, the carrier’s amplitude is varied in proportion to the input signal, producing the familiar form used in AM radio broadcasting. Frequency modulation varies the instantaneous frequency of the carrier, as in FM radio and many television audio systems. Phase modulation changes the phase of the carrier; a subset of PM, quadrature amplitude modulation (QAM), and phase‑shift keying (PSK) techniques are widely used in digital signalling.

Mathematically, a modulated signal s(t) may be expressed as s(t)=A(t) cos[2πf_c t + φ(t)], where f_c is the carrier frequency, A(t) represents the amplitude envelope, and φ(t) the phase deviation induced by the message. Demodulation (or detuning) processes reverse this operation to recover the original information.

The concept dates back to the early twentieth century, with significant contributions from Edwin Armstrong and his development of frequency modulation in the 1930s. Today, dimodulasi underpins virtually all wireless communication, from broadcast radio to modern cellular networks, satellite links, and wireless computer networking.