modulatsioonitehnikad

Modulatsioonitehnikad refer to methods used in telecommunications and signal processing to alter a carrier signal's properties in accordance with a modulating signal. This process allows information to be transmitted efficiently over a communication channel. The primary goal of modulation is to adapt the information signal, which often has a low frequency, to a carrier signal that has a higher frequency, making it suitable for transmission over radio waves or other media.

Amplitude modulation (AM) is a technique where the amplitude of the carrier signal is varied in proportion to the message signal. This was one of the earliest modulation methods used for broadcasting. Frequency modulation (FM) alters the frequency of the carrier wave based on the amplitude of the message signal. FM is known for its higher fidelity and resistance to noise compared to AM. Phase modulation (PM) changes the phase of the carrier signal in accordance with the message signal. PM is closely related to FM and can be converted to it.

Digital modulation techniques are used for transmitting digital data. Amplitude-shift keying (ASK) represents digital data by varying the amplitude of the carrier signal. Frequency-shift keying (FSK) uses different frequencies to represent binary values. Phase-shift keying (PSK) uses different phases to represent binary values. Quadrature amplitude modulation (QAM) combines both amplitude and phase modulation to transmit more data with each symbol, achieving higher spectral efficiency. The choice of modulation technique depends on factors such as desired data rate, bandwidth availability, noise immunity, and hardware complexity.