modulators and de-modulators

What is a Modulator / Demodulator?

A radio frequency modulator (or RF modulator) takes a baseband input signal and then outputs a radio frequency modulated signal. This is often a preliminary step in signal transmission, either by antenna or to another device such as a television.

A demodulator is a circuit that is used in amplitude modulation and frequency modulation receivers in order to separate the information that was modulated onto the carrier from the carrier itself. A demodulator is the analog part of the modulator. A modulator puts the information onto a carrier wave at the transmitter end and then a demodulator pulls it so it can be processed and used on the receiver end.

Types of Modulators / Demodulators

There are many different kinds of modulators / demodulators. At Future Electronics we stock many of the most common types categorized by supply voltage, operating frequency, signal-to-noise-ratio, packaging type and power dissipation. The parametric filters on our website can help refine your search results depending on the required specifications.

The most common sizes for power dissipation are 33 mW and 200 mW. We also carry modulators / demodulators with power dissipation up to 600 mW. Operating frequency can range from 455 kHz to 2500 MHz, with the most common ranges being 460 to 880 kHz and 1 to 100 MHz.

This page on Modulator vs Demodulator covers basics of Modulator and Demodulator and also mentiondifference 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➤➤.

Modulator

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➤➤.

 
Figure-1 Modulator Demodulator Process

Demodulator

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.