Analog Communication Tutorial

What is Analog Communication?

Communication is defined as a method of exchanging data and information. When the communication is accomplished by using analog signals, then it is referred to as Analog Communication. In more simple words, analog communication is the exchange of information in the form of analog signals that represent information in the form of continuous time functions. Sound waves or voice signals are the common examples of analog signals.

Analog communication is most widely used in AM or FM radio broadcasting, TV broadcasting, telephonic voice communication, and various measuring and instrumentation applications.

Analog communication is known for its simpler design and high fidelity. However, it is very sensitive to noise and electromagnetic interference. It also has limited communication range.

About the Analog Communication Tutorial

The main objective of this comprehensive Tutorial on Analog Communication is to provide understanding of fundamental principles of communication systems that are based on analog signals and are known as analog communication.

This tutorial is divided into 25 chapters −

• The opening chapter is an introductory chapter that provides the definition of communication, parts of a communication system, and types of signals.
• The definition, needs, advantages and types of modulation are discussed in the next chapter of this tutorial. Major concepts related to amplitude modulation like time domain representation of AM waves, modulation index, bandwidth of AM wave, and power calculation of AM wave are summarized in the chapter 3 of the tutorial.
• Chapter 4 provides a few solved numerical problems based on the concepts of amplitude modulation discussed in the previous chapters. With this as background, chapter 5 describes the two common types of amplitude am modulators namely, square law modulator and switching modulator.
• You will learn about AM demodulators and their types square law demodulator and envelope detector in the chapter 6.
• In chapter 7, you will learn about Double Sideband Suppressed Carrier (DSBSC) modulation and related concepts such as bandwidth of DSBSC signal and power calculation of DSBSC wave.
• In chapters 8 and 9, you will study about the DSBSC modulators balanced modulator and ring modulator, and DSBSC demodulators coherent detector and costas loop respectively.
• The chapters 10, 11, and 12 describe the Single Sideband Suppressed Carrier (SSBSC) modulation, SSBSC modulators frequency discrimination method and phase discrimination method, and SSBSC demodulator coherent detector.
• In the chapter 13 of this tutorial, you will learn about Vestigial Side Band Suppressed Carrier (VSBSC) Modulation along with bandwidth, advantages, disadvantages, and applications of VSBSC.
• Angle modulation, frequency modulation, and phase modulation are described in the chapter 14. The chapter 15 provides a few solved numerical problems 2 based on the concept of frequency modulation.
• Chapters 16 and 17 explains the theory of FM modulators and FM demodulators. Theory of multiplexing and different types of multiplexing such as analog multiplexing, digital multiplexing FDM, WDM, TDM, etc. are discussed in the chapter 18.
• Noise, types of noise, and effects of noise are explained in the chapter 19 of this tutorial. The chapter 20 describes the theory of Signal to Noise Ratio (SNR) and its calculation in different types of modulation systems.
• Transmitter and receiver are described in the chapters 21 and 22. The concept of sampling and sampling theorem are discussed in the chapter 23.
• Chapter 24 explains the pulse modulation pulse amplitude modulation, pulse width modulation, and pulse position modulation. The final chapter of this tutorial describes the needs and types of transducers.

At the end of the tutorial, we will get a quick guide, other useful resources, and a discussion platform for reader engagement.

Prerequisites to use the Analog Communication

To take full benefit of this tutorial, we recommend that you have −

• A basic knowledge of electronics concepts like current, voltage, power, frequency, etc.
• A basic knowledge of communication and its needs.

For a better understanding of this tutorial, you can explore our Signals and Systems Tutorial which will help you building a foundational background to understand the topics discussed here.

Features of Analog Communication

Here are some key features of analog communication −

• Detailed Explanation − In this tutorial, each topic related to analog communication such as, analog modulation techniques, amplitude modulation, frequency modulation, DSBSC modulation, SSBSC modulation, VSBSC modulation, pulse modulation, etc. are discussed in detail.
• Solved Examples − This tutorial also includes solved numerical problems to demonstrate the application of concepts and formulae.
• Organized Content − This tutorial is organized in a way that each chapter links with the previous chapter in a chronological order.
• Reader Friendly Writing Style − The tutorial is written in a lucid and simple to reader English. So, an absolute beginner can also take benefit from this tutorial.

FAQs on Analog Communication

In this section, we have assembled a set of Frequently Asked Questions on Analog Communication followed by their answers −

1. What is analog communication?

A communication method in which the information is transmitted using continuous time signals is known as analog communication. In simple words, analog communication is a type of communication that transmits information in the form of analog signals.

Analog signals continuously vary in amplitude, frequency, or phase with respect to time. Analog signals are represented using waveforms. Common examples of analog signals include AM or FM radio signals.

Analog communication is used in various applications to transmit real-world information in its original form.

2. Why are analog signals still being used in communication?

Analog signals are still being used in communication because of following major reasons −

• They can directly represent real-world information.
• Analog signals can represent variety of signals like voice signals, radio signals, TV signals, etc.
• The systems using analog signals are simple and less expensive than digital systems.
• Analog communication is compatible with legacy infrastructures.
• Analog signals provide a natura and continuous flow of information, making them suitable for real-time applications like voice communication.

3. What are the advantages and disadvantages of analog communication?

Analog communication has several advantages and disadvantages, major of them are listed below −

4. What does analog mean and how does it differ from digital?

Analog is a term that represents, a given signal or quantity has a continuous and smooth variation with respect to time. It is used to represent continuous time signals, known as analog signals.

Analog signals are different from digital signals in various aspects as follows −

• Analog signals are continuous over time while digital signals discontinuous or discrete with respect to time.
• Analog signals are represented using waveforms, while digital signals are represented using binary codes.
• Analog signals are sensitive to noise and interference, while digital signals are resistant to noise and interference.
• Analog signals are complex to store, while digital signals are easy to store.

5. What is the basic difference between analog and digital communication?

The main difference between analog and digital communication is that analog communication transmits information using analog signals (continuous time signals), while digital communication uses discrete signals (discontinuous time signals) for information transmission.

6. What is an example of an analog communication method?

Amplitude Modulation (AM) Radio broadcasting is a common example of analog communication method. In this communication method, the amplitude or strength of the carrier signal is modulated according to the original radio signal.

7. What are the types of analog communication?

Depending on the type of modulation used, analog communication can be classified into the following main types −

• AM Analog Communication − In AM analog communication, the message signal is amplitude modulated with the carrier signal.
• FM Analog Communication − In FM analog communication, the message signal is superimposed with a frequency modulated carrier signal.
• PM Analog Communication − PM stands for Phase Modulation. In this type of analog communication, the message signal is superimposed with a phase modulated carrier signal.

8. What is analog communication media?

Communication media is nothing but the channel through which communication signals are transmitted between transmitter and receiver.

In analog communication, the most commonly used communication media are listed below −

• Twisted-Pair Cables − These cables have two conductors of a single circuit which are twisted together. These cables are mainly used in telephone lines for transmission of voice and analog data signals.
• Coaxial Cables − These cables consist of an inner copper conductor surrounded by a conducting shield, and the central conductor and shield are separated by a dielectric layer. At the outmost surface, a protective jacket is provided. These cables are employed in cable TV broadcasting for analog signal transmission.
• Optical Fiber − Optical fiber is a communication cable made up of glass or plastic fibers for analog signal transmission in the form of light. This communication media is widely being used in modern telecommunication systems.
• Radio Waves − Radio waves are also used as an analog communication medium for data transmission. Radio waves are electromagnetic signals, having lowest frequencies ad longest wavelengths. These waves are used for wireless analog communication like AM or FM radios.

9. Why are only cosine waves used in analog communication?

Cosine waves are used in analog communication, instead of sine waves. The primary reasons behind this are listed as follows −

• Cosine waves are easy to represent and manipulate mathematically.
• Cosine waves starts at their maximum value which makes their analysis and calculations easier.
• Cosine waves offer convenience in mathematical modeling.
• Cosine waves represent the real part of a complex exponential function used in analog communication.
• Cosine waves represent more natural parts of the signals that aligns with the practices in analog communication.

10. When is analog communication preferred to digital?

Analog communication is preferred over the digital communication in the following situations −

• For transmission of audio and video signals.
• When real-time signal processing is desired.
• When data transmission is done with limited bandwidth.
• For transmission of data related to changes in physical phenomena like temperature, pressure, current, voltage, etc.

11. How is noise described in analog communications?

In analog communication, noise is defined as unwanted signals that can degrade the quality of original message signal.

Depending on the characteristics, several different types of noises can occur in the analog communication, such as −

• Thermal or Johnson noise
• Transient time noise
• Shot noise
• Flicker noise
• Electromagnetic interference, etc.

12. What is modulation in communication?

In communication, modulation is a process of encoding message signal onto a carrier signal for transmission. In analog communication, the modulation is performed by modifying the characteristics like amplitude, frequency, phase, etc. of the carrier signal. This variation depends on the message signal to be transmitted.

The main objective of modulation in communication is to optimize the message signal, so that it can be transmitted over long distances through a suitable communication medium.

13. What are the types of AM modulation?

Amplitude Modulation (AM) can be classified into following main types −

• Double Sideband Full Carrier (DSBFC) − DSBFC is a standard type of the amplitude modulation. In this type of AM modulation, both sidebands and the carrier signal are transmitted as it is. It is a simplest type of amplitude modulation, but it is less efficient in terms of power consumption and bandwidth utilization.
• Double Sideband Suppressed Carrier (DSBSC) − In this type of amplitude modulation, both sidebands are transmitted, but the carrier signal is suppressed to reduce the power consumption. In this AM modulation, the receiver has to regenerate the carrier signal from its suppressed version during demodulation.
• Single Sideband Suppressed Carrier (SSBSC) − In this type of amplitude modulation, only one sideband is transmitted with a suppressed carrier signal. This AM modulation is used where less bandwidth and power efficiency are required.
• Vestigial Sideband Modulation (VSBM) − This is a type of AM modulation in which one full sideband and a part of the other sideband is transmitted. It is used to solve the problems associated with DSB and SSB modulations. VSBM is commonly used in TV broadcasting applications where a balance between signal quality and bandwidth efficiency is critical.

14. What is AM modulator and demodulator?

In analog communication, AM modulator and demodulator are two main components of the communication system. An AM modulator is a device that performs modulation of carrier signal by varying its amplitude. It combines the carrier signal with the message signal to be transmitted. Hence, AM modulator is provided at the sending end of the communication system.

On the other hand, an AM demodulator is a device that performs opposite function of the AM modulator. It retrieves the original message signals from the AM modulated signal and is used at the receiving end of the communication system.

15. What is a transmitter in analog communication?

In analog communication, a device which is used for transmitting data or information is known as a transmitter. The transmitter first converts the data or information into a suitable form like electric signals, radio waves, optical signals, etc. and the sends them to the receiver.

The main purpose of using a transmitter in analog communication is to send information over a distance.