demodulaation

Demodulation, sometimes spelled demodulaation, is the process of extracting the original information signal from a modulated carrier. It is the inverse operation of modulation and a fundamental function in communication systems and receivers. Demodulation converts a modulated waveform back to baseband or to a format usable by the destination device.

In analog communication, demodulation recovers audio or video from AM, FM, or PM signals. AM demodulation commonly uses envelope detection, while FM demodulation relies on frequency discrimination or phase-locked loop techniques; PM demodulation uses phase detectors. In digital communication, demodulation recovers digital symbols from schemes such as ASK, FSK, PSK, and QAM. Digital receivers employ coherent detection with a reference carrier or non-coherent detection, often together with matched filtering, symbol timing recovery, and decision logic.

Implementation and challenges: Demodulators are built into receivers and may include components such as mixers, local oscillators, detectors, and analog-to-digital converters. Performance is affected by noise, interference, channel distortion, and synchronization errors. Modern systems frequently use digital signal processing to perform demodulation and accompanying error correction, enabling robust data recovery across noisy or fading channels. In fiber-optic and wireless links, advanced demodulation schemes—often coherent and digitally aided—improve sensitivity and spectral efficiency.