modulaatori

Modulaatori are electronic devices or software modules that impose information signals onto a carrier wave by altering one or more characteristics of the carrier, such as its amplitude, frequency, or phase. By encoding data in these variations, modulators enable transmission of information over physical media including air, coaxial cables, and optical links. They are a fundamental component of most communication systems.

Modulation methods fall into two broad categories. Analog modulators implement amplitude modulation (AM), frequency modulation (FM), or phase modulation (PM), where the baseband signal directly influences the carrier’s properties. Digital modulators map a stream of bits into symbols using schemes such as quadrature amplitude modulation (QAM), phase-shift keying (PSK), or frequency-shift keying (FSK); these digital schemes are often combined with multi-carrier or orthogonal techniques like OFDM to improve spectral efficiency. Hybrid approaches integrate analog and digital processing in a single path.

Typical modulators consist of a baseband or intermediate-frequency signal path, a local oscillator, and a mixer or multiplier stage that combines them. In digital modulators, the sequence is mapped to symbols by a digital processor, upsampled and converted by a DAC before modulation. Analog modulators rely on nonlinear devices or modulators to vary the carrier directly, followed by filtering to control spectral content.

Common applications include radio broadcasting and television, satellite communications, cellular networks, Wi‑Fi and other data links, telemetry, and radar. The development of modulation techniques has driven increases in channel capacity and robustness in noisy environments.