Modulaatorisignaali

Modulaatorisignaali, commonly referred to as the modulating signal or message signal, is the signal that carries the information to be transmitted. In the process of modulation, this signal is used to alter a characteristic of a carrier signal. The information content of the modulatorisignaali can be analog, such as an audio waveform from a microphone, or digital, represented by a sequence of bits.

The purpose of modulation is to prepare the information signal for transmission over a communication channel. Often, the original information signal is not suitable for direct transmission due to limitations in bandwidth, antenna size, or susceptibility to noise and interference. By modulating a carrier signal, the information can be shifted to a higher frequency range, which is more efficient for propagation.

Different types of modulation exist, each altering a specific property of the carrier wave based on the modulatorisignaali. In amplitude modulation (AM), the amplitude of the carrier is varied. In frequency modulation (FM), the frequency of the carrier is varied. In phase modulation (PM), the phase of the carrier is varied. Digital modulation techniques like phase-shift keying (PSK) and quadrature amplitude modulation (QAM) encode digital data into the carrier signal. The modulatorisignaali's characteristics directly determine the variations in the carrier, thereby embedding the information.