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Modulator vs Demodulator-Difference between modulator,demodulator

This page on Modulator vs Demodulator covers basics of Modulator and Demodulator and also mention difference between Modulator and Demodulator.

As we know in telecommunication, in order to send information to longer distance and to take care of high bit rate requirement of the system different modulation techniques are employed. There are two main types of modulation i.e. analog and digital. In analog modulation, baseband information which need to be transmitted is analog. In digital modulation, baseband information which need to be transmitted is digital (i.e. consists of binary 1's and 0's). Refer What is Modulation➤➤.


The device which does the funtion of modulation is referred as modulator. The modulator device which works on Radio Frequency is known as RF modulator. Modulator converts input information bits into complex waveform. The parameters of output waveform is changed as per modulating input signal based on modulation type.

Typical analog modulators include AM, FM and PM while digital modulators include ASK, FSK, PSK, 16QAM, 64QAM and 256QAM. The figure-1 depicts digital modulator and demodulator of FSK type. Here frequency of the carrier input is varied as per modulating signal input. For binary 1 , frequency f1 is the output while for binary 0, f2 is the output.

In AM or ASK, amplitude of the carrier is changed as per baseband modulating signal input. For PM and PSK, phase of the carrier is changed as per input. Refer ASK vs FSK vs PSK➤➤ and AM vs FM vs PM➤➤.

Modulator Demodulator
Figure-1 Modulator Demodulator Process


The device which does the funtion of demodulation is referred as demodulator. The demodulator device which works on Radio Frequency is known as RF demodulator. The demodulator will convert received complex waveform into baseband informations (i.e. analog or digital).

Following table lists out typical modulation techniques widely used in various RF, Microwave and Wireless communication systems for various applications.

Modulation technique Description
BPSK Binary Phase Shift Keying, used for robust long distance communication, Refer BPSK modulator➤➤
QPSK Quadrature Phase Shift Keying, used for compromise between long distance and medium data rate requirement, Refer QPSK modulation➤➤
8-PSK 8 level phase shift keying, Refer 8-PSK modulator
QAM Quadrature Amplitude Modulator, It utilizes both QPSK and PSK functionalities. It is used to increase data rate of the system, QAM➤➤
MSK, GMSK Minimum Shift Keying and Gaussian Minimum Shift Keying, Used in GSM technology. MSK-GMSK➤➤
DPSK Differential Phase Shift Keying, Refer DPSK modulator demodulator➤➤
OQPSK Offset QPSK, Refer OQPSK Modulator➤➤
SSB, VSB SSB stands for Single Sideband Modulation, VSB stands for Vestigial Sideband Modulation, Refer SSB vs VSB➤➤
SSBSC, DSBSC SSBSC stands for Single Sideband Suppressed Carrier, DSBSC stands for Double Sideband Suppressed Carrier, Refer DSB-SC vs SSB-SC.

What is Difference between

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Difference between TDD and FDD
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Diplexer versus Duplexer
Sensitivity Vs. selectivity

RF and Wireless Terminologies

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