Modulation and its Types

By superimposing a carrier signal on top of the underlying signal, you can change its fundamental features. This is done in order for the basic signal to travel from one point to another point. Many operations, such as video chatting and conversing to individuals all across the world, require modulation.

Modulation

Information, messages, and signals may now be sent in seconds due to modern technology. Modulation is used in communication systems to increase the range of communications. Sinusoidal waves make up the majority of signals we encounter in our daily lives.

Modulation is the addition of information to an electrical or optical carrier signal in order to convert data into radio waves. A carrier signal has a waveform which has constant amplitude (height) and frequency.

Sinusoidal waves are oscillations which are smooth and repetitive. Signal communication methods involve the transmission of data in the form of sinusoidal waves. Modulation is essential for transferring signals rapidly from sender to receiver.

Types of Modulation

There are three types of modulation which are given here.

1. Amplitude Modulation (AM)
2. Frequency Modulation (FM)
3. Phase Modulation (PM)

Amplitude Modulation (AM)

Amplitude modulation was invented at the start of the 20th century. It was the first modulation technology used to send voice over the radio. In electronic communication, this form of modulation is applied. The carrier signal’s amplitude varies in response to the message signal, but other parameters such as phase and frequency stay constant.

Amplitude modulation occurs when the amplitude of basic signal changes or modulates when it is superimposed with a carrier signal of same frequency but different amplitude.

Frequency Modulation (FM)

In frequency modulation, the carrier signal’s frequency changes in response to the message signal, while other characteristics such as amplitude and phase stay constant. Frequency modulation is widely used in a variety of applications, including radar, radio, and telemetry, seismic prospecting, and EEG monitoring of newborn for seizures.

Frequency modulation occurs when the frequency of the base signal changes or modulates when it is superimposed by a carrier signal of same amplitude but different frequency.

Phase Modulation

The carrier signal’s phase varies in phase with the message signal in phase modulation. When the phase of a signal changes, the frequency changes as well. As a result, this modulation is also classified as frequency modulation.

In most cases, phase modulation is used to transmit waves. It is an important component of several digital transmission coding methods that support a variety of technologies, including GSM, WiFi, and satellite television. 

Phase modulation occurs when the phase of the base signal changes when it is superimposed with a carrier signal.

Applications of Modulation

There are many applications of modulation, some of which are given here.

1. For the inter-conversion of signals from one form to another, various types of modulation are used.
2. Transmissions of digital signals across analogue baseband are done using digital modulation.
3. Transfer of low bandwidth signals over higher bandwidth is done through Analog modulation.
4. Frequency Division Multiplexing uses modern modulation.

Modulation in Communication

Multiple carriers of various frequencies can frequently be transmitted across a single medium, each modulated by a separate signal. Wi-Fi, for example, employs individual channels to send and receive data from several clients at the same time.

For efficient transmission and reception, a carrier signal is used to decrease the wavelength. An audio frequency of 3000 Hz will need a wavelength of 100 km and a 25-kilometer antenna since the ideal antenna size is one-half or one-quarter of a wavelength. Instead, the antenna would only need to be 80 cm long if it used a 100 MHz FM carrier with a wavelength of 3 metres.

Modulation Index

The modulation index indicates how much modulation is done on a carrier signal. Modulation index is defined as the ratio of the modulating signal’s amplitude to that of the carrier signal in amplitude modulation.

m=Am/Ac

Here, 

Am  = amplitude of modulating signal

Ac  = amplitude of carrier signal

Demodulation

Extraction of the original information-carrying signal from a modified carrier wave is known as demodulation. A demodulator is an electrical circuit which recovers information from a modulated carrier wave. A demodulator’s output signal can describe sound, pictures, or binary data.

Conclusion

Modulation is the addition of information to an electrical or optical carrier signal in order to convert data into radio waves.

There are three types of modulation which are given here.

1. Amplitude Modulation (AM)
2. Frequency Modulation (FM)
3. Phase Modulation (PM)

Amplitude modulation occurs when the amplitude of basic signal changes or modulates when it is superimposed with a carrier signal of same frequency but different amplitude.

Frequency modulation occurs when the frequency of the base signal changes or modulates when it is superimposed by a carrier signal of same amplitude but different frequency.

Phase modulation occurs when the phase of the base signal changes when it is superimposed with a carrier signal.

For the inter-conversion of signals from one form to another, various types of modulation are used.