modulált

Modulált describes a signal in which a carrier wave is varied in time by a modulating signal to encode information. In telecommunications, modulation enables transmission of information over a channel, allowing changes in bandwidth, power efficiency, and propagation characteristics to be managed.

Common forms include amplitude modulation (AM), where the carrier amplitude varies with the modulating signal; frequency modulation (FM), where the instantaneous frequency follows the modulating signal; and phase modulation (PM), where the instantaneous phase changes according to the modulating signal. Modern communication also uses digital modulation techniques that modify amplitude, phase, or frequency to convey data, such as phase-shift keying (PSK), quadrature amplitude modulation (QAM), and frequency-shift keying (FSK).

At the receiver, demodulation recovers the original modulating signal from the modulated carrier. The choice of modulation scheme affects bandwidth requirements, power efficiency, and resilience to noise. AM is simple and widely used in broadcasting but relatively susceptible to noise; FM offers improved noise performance and is common in radio broadcasting; digital schemes enable higher data rates and robust transmission in data networks.

Historically, modulation concepts emerged with the development of radio in the early 20th century. Amplitude modulation played a foundational role in early broadcasting, while later innovations, including Edwin Armstrong’s development of FM and the rise of digital modulation methods, expanded the capabilities and applications of modulated signals across communications, data links, and wireless networks.