Modulation and Demodulation


Modulation and demodulation are fundamental processes in telecommunications that involve the encoding (modulation) and decoding (demodulation) of information onto a carrier signal for transmission and reception, respectively.


Modulation is the process of changing one or more properties of the carrier signal in proportion with the information signal. In modulation, some parameter of the carrier wave (such as amplitude, frequency or phase ) is varied in accordance with the modulating signal . This modulated signal is then transmitted by the transmitter

Demodulation is the reverse process of modulation and convert the modulated carrier back to the original information.

Components of Modulation system


It is the circuit which performs modulation.

Information / Message / Modulating Signal

It is the base signal to be transmit. It is low frequency signal.

Carrier Signal

It is the high frequency signal use to carry information signal.

Modulated Wave / Signal

It is the carrier signal that has been acted on by information signal.It is high frequency signal.


Demodulator is a circuit in receiver which performs demodulation.

Types of Electronic Communication

Analog Communication System.
In analog communication system, both the information and carrier are in analog form. Radio broadcasting.

Digital Communication System.
It is divided in two parts.

Digital Transmission.
Digital pulses are transmitted from source to destination. It requires a physical medium between source and destination. Fiber optic transmission.
Line coding is used in digital transmission.

Digital radio.
Digital pulses modulates an analog carrier. Transmission medium may be wired or wireless.


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