What is Modulation?

Modulation can be digital or analog, the input wave of the analog signal varies continuously like a sine wave. Modulation can be defined as the process of converting data into waves by adding information to a carrier signal. Such a signal can be transmitted electronically or optically, but it must have a consistent waveform.

What is Modulation?

The process by which data is converted into electrical/digital signals for transferring that signal over a medium is called modulation. It increases strength for maximum reach of the signals. The process of extracting data from the transmitted signal is called demodulation. A Modem is a device that performs both modulation and demodulation processes. The various forms of modulation are designed to alter the characteristics of carrier waves. The most commonly altered characteristics of modulation include amplitude, frequency, and phase.

• Carrier signal: The signals that contain no information but have a certain phase, frequency, and amplitude are called carrier signals.
• Modulated signals: The signals which are the combination of the carrier signals and modulation signals are modulated signals. The modulated signal is obtained after the modulation of the signals.

Types of Modulation

• Amplitude Modulation: It is a type of modulation in which only the amplitude of the carrier signal is varied to represent the data being added to the signals whereas the phase and the frequency of the signal are kept unchanged.

Amplitude Modulation

• Frequency Modulation: It is a type of modulation in which only the frequency of the carrier signal is varied to represent the frequency of the data whereas the phase and the amplitude of the signals are kept unchanged.

Frequency Modulation

• Phase Modulation: It is a type of modulation in which the phase of the carrier signal is varied to represent the data being added to the signal. Different information values are represented by different phases. For example: ‘1’ may be represented by 0° while ‘0’ by 180°.

Phase Modulation

What is the Need of Modulation?

• Size of Antenna: As we know that the size of the antenna is inversely proportional to the frequency of the radiated signal and antenna size must be 1/10th of the wavelength. If the frequency signals are more than 5KHz in that case it is quite impossible to set up an antenna of that size. So, by using the modulation technique the size of the antenna is reduced.
• Wireless Communication: Modulation provides a wireless connection to transmit the signals to a longer distance. Earlier we used wire systems (like the telephone) to transfer information with the help of telephonic wires but it was not possible to spread the wires all over the world for communication. By using the modulation technique, the cost of wire is saved and even information can be transferred to longer distances faster. 

Working of Modulation 

Data can be added to the carrier signal by varying its amplitude, frequency, and phase. Basically, modulation is applied to electromagnetic signals like radio waves, optics, and computer networks. It can also be applied to direct current that can be treated as a degenerate carrier wave with a fixed amplitude and frequency of 0 Hz by turning it off and on as in a digital current loop and in Morse code telegraphy. 

Advantages of Modulation

• It reduces the size of the antenna.
• It reduces the cost of wires.
• It prohibits the mixing of signals.
• It increases the range of communication.
• It improves the reception quality.
• It easily multiplexes the signals.
• It also allows the adjustment of the bandwidth.

Disadvantages of Modulation

• The cost of the equipment is higher.
• The receiver and the transmitter are very complicated.
• For better communication, the antennas for the FM system must be kept closed.
• It is not efficient for large bandwidth. 
• Power wastage takes place.

Define Duty Cycle

In wireless communications, the duty cycle is the percentage of time the wireless network emits RF signals. As a result, the duty cycle is an important factor when measuring a person’s exposure to electromagnetic radiation. The actual duty cycle differs based on the network’s data load and speed. As a result, the duty cycle can be changed by whether the network is used for Voice Over Internet Protocol(VoIP), streaming videos, or videos.

Difference Between Modulation and Demodulation

Modulation	Demodulation
The process by which data is converted into electrical/digital signals for transferring that signal over a medium is called modulation.	The process of extracting data from the transmitted signal is called demodulation.
Modulation is connected from transmitting end.	Demodulation is connected from Receiving end.
Modulation converts digital signal to analog signal.	Demodulation converts analog signal to digital signal.
The transmission of frequency in modulation goes low to high.	The transmission of frequency in demodulation goes high to low.
In modulation, the circuit used is modulator.	In demodulation, the circuit used is demodulator.

Frequently Asked Question on Modulation – FAQs

How does Modulation affect Bandwidth?

Modulation can change the bandwidth of a transmission. For example, AM and FM signals require different bandwidths. In general, higher modulation rates and more complex modulation methods require larger bandwidths.

What is the Modulation Index?

The modulation index is a measurement of the degree of modulation in a modulated signal. It quantifies the amount by which the modulating signal modifies the carrier signal.

Which device is used for Modulation and Demodulation?

The modem is the device that is used for modulation and demodulation. Modem is the process of converting analog signal to digital signal and vice versa. It can modulate and demodulate the signals of each other.