Hello everyone, hope you all are doing excellent. The topic on which we are gonna discuss today is a communication system, its importance, block diagram, elements, and its features. The term “communication” covers a very broad range of regions. whereas it encloses a large number of fields of study, ranging from the use of symbols to the social implication and effect. The meaning of the term communication is the transfer of data from one point to another. It can also be termed as telecommunication for instance.


block diagram communication system

Information Source

Information source is the place from where the information originates. Generally, information can be of any type for example text, image, audio, video. To sum up we can say it is the quantity which is to be transferred.


It is a single-valued function that changes subsequently with the temperature. Certainly, its main function is to convert physical into information for transmission.


Above all the main function is of the transducer is to convert energy from one form to another. The electrical transducer converts physical quantities into consecutive electrical quantities. For example, a Microphone converts audio energy into an electrical signal, Temperature sensors convert heat energy into electrical energy.


Transmission of signal over a large distance is quite difficult thus, we use a technique known as modulation. This process however involves two signals;

  1. Information signal
  2. carrier signal

However, here information signal is a baseband (low-frequency signal ) and carrier is a high-frequency signal

Types of Modulation in the Communication system

1. Amplitude modulation in communication system

So if the amplitude of the high-frequency carrier wave changes consequently with the changes in the amplitude of the modulating signal then such a method of approach is called amplitude modulation.

For example; broadcast transmission, radio stations.

waveform of phase modulation in a communication system
  1. simple to implement because of its simple structure.
  2. costly.
  3. demodulation is quite reliable as it uses a very few of components for the process.
  1. Power efficiency is quite low because of difference in the power level of radio wave components.
  2. The efficiency of the spectral signal also decreases with consequent increase of pressure on the radio signal.
  3. It get easily disturbed with the noise signal because of the the nature noise signal which is amplitude based.

Frequency Modulation in communication system

If the frequency of the high-frequency carrier signal changes respectively with the changes in the value of the modulating signal then, such a method is known as frequency modulation.

waveform of frequency modulation in a communication system

For example; radar, telemetry, ECG.

  1. Resistance to noise interference
  2. it is possible to apply frequency modulation to low power stage transmitter besides it also doesn’t requires a linear system.
  1. Similarly to AM modulation it also doesn’t have efficient spectrum.
  2. secondly its demodulating signal is also a bit complex.
  3. The sidebands of the FM modulation are ideally extendable to infinity on both the sides. However, to limit this affect filter are to be used but, due this the signal gets distorted.

Angle Modulation in communication system

If the angle of the high-frequency carrier signal changes respectively with the instantaneous changes in the value of the modulating signal then such method of modulation is known as angle modulation.

For example; stereo decoder, magnetic tape storage.

Phase modulation in communication system

If the phase of the high-frequency carrier signal changes respectively with the instantaneous changes in the value of the modulating signal then such method of modulation is known as angle modulation.

For example; digital synthesis, GPS systems, radio wave transmission.

waveform of phase modulation in a communication system
  1. Simpler than frequency modulation.
  2. Above all its main advantage is signal modulation as it provides computer for commutating on high speed over telephones.
  3. Immunity towards noise interference.
  1. Complexity of structure is high because of lar.
  2. Ambiguity(quality of being open to interpretation) occurs if we exceed index pi radian(1800).
  3. Costly because of its more hardware requires.

Modulation index

The modulation index is defined as the extent to which the variable of carrier signal changes subsequently with its unmodulated level.

It ranges between 0 to 1 where;

m = Vm / Vc

    \[M =\frac {V_m_a_x - V_m_i_n} {V_m_a_x + V_m_i_n}\end.\]

importantly, there are four possibilities of index modulation;

  1. m = 0 (No modulation)
  2. m = 1 (full modulation)
  3. cracks occurs in the signal (m >1 )
  4. amplitude changes by 50% (m < 1)


It processes the information into a suitable message signal for transmission and further for reception.


It is the medium through which the information passes between the source and destination. Moreover, the channel can be of any type wired or wireless.


Noise is the unwanted signal which interferes with the main signal. Certainly, it is random in character. and has a great effect on the signal system.


moreover, the main function of a receiver is to reproduce the original information signal from the distorted signal(in other words from the signal containing noise). This reproduction is to be known as demodulation.


It is the final stage of the communication system it receives the message and further processes it back to its original form from the electrical signal.


Depending on Nature of Signal

Analog communication system

Analog communication is a mode of conveying data using a continuous signal which varies subsequently with the changes in amplitude, phase, and angle in proportion to that of a variable. It uses an analog signal for representation.

waveform of analog signal in a communication system

Digital communication system

In the digital communication system, the data is generated and processed only in between two states that are 0 (low) and 1 (high). So we can sum up and say as it transfers the data between two-point.

waveform of digital signal communication system

Depending on the type of channel

1.Wired Communication System

So it is a mode of communication that involves the transmission of data over a region with the help of wire for example telephone networks/ cables.

Advantages of wired communication system
  1. Faster uploading and downloading skills since it is simple in structure.
  2. Security from hacking in other words from unauthorized networks.

2.Wireless Communication System

It is a mode of communication that includes data transmission over a region without the help of cables, wires, or any electrical conductor. For example Wi-Fi, Television remote control.

if you wanna get a deeper look at what the control system is then check the link below;

Control system

Advantages of wireless communication system
  1. Economical because it doesn’t requires the installation charges of cables.
  2. Certainly it is most flexible and adaptable to surrounding.
  3. Data is transferred at a Speed.
  4. Accessibility.
  5. In addition to all it is the most convenient.

Depending on the Physical Infrastructure

  1. Line communication system. For example landline telephony
  2. Radio communication system. For example long distance telephony

Fourier Transform

Basically, the Fourier transform provides a link between the time-domain and frequency-domain features of a signal. The waveform of the signal and its spectrum are two main points on which the nature of the signal is decided. Let g(t) denotes a non-periodic deterministic signal, given as a function of time t. So, the Fourier transform of the signal g(t) is;

g(F) = ∫-∞+∞ g(t)e(-jnw0t)

where j = √-1;

g(F) = ∫-∞+∞ g(t)e(jnw0t)

for the Fourier transform of a signal g(t) to exist, it is sufficient, but not necessary, that g(t) satisfies three conditions known collectively as Dirichlet’s condition.

  1. The function g(t) is single-value, with a finite number of maxima and minima in any finite time interval.
  2. The function g(t) has number of discontinuities in any finite time interval.
  3. Function g(t) is absolutely integrable, for instance,

-∞+∞ |g(t)|dt < ∞

In other words, physical realizability is a sufficient condition for the Fourier transform. Indeed, we can sum up and state that all energy signals, that is, signal g(t) for which are Fourier transformable

-∞+∞ |g(t)|2dt < ∞.


A simple notation for the transform relations of equations is;

G(f) = F[g(t)]

and g(t) = F-1[G(f)]


Hope you got all of your doubts clear and are satisfied with the content provided. If you like then please make sure to tell me down below the part which you liked the most and share it with others. Besides if you have any doubt then please let me know. And above all, I would be very happy if suggest the topic on which you would like to read further.

Have a nice day:)


Read More,

  1. Mosfet( Construction, Working and Characteristic)
  2. Control system (features, types etc.)


  • Dhruv February 28, 2021 at 3:26 pm Reply

    Mam Plz upload blogs frequently….u r keeping us waiting so much…. And it is very interesting blog mam😆😆

  • Jadhav Prathamesh February 28, 2021 at 3:34 pm Reply

    Liked the way how you cover and present the info ….

  • Aman February 28, 2021 at 3:38 pm Reply

    Excellent work

  • Kalyani Ananta Dhande February 28, 2021 at 4:29 pm Reply


  • Amruta hanimanale March 1, 2021 at 7:30 am Reply

    Its easy to understanding… i like it…

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