Transmission Impairment- Attenuation, Distortion, Noise

Transmission Impairment- Attenuation, Distortion, Noise

Transmission Impairment

Hi everyone

We will be discussing Transmission Impairment.

This is also one of the important topics of computer networks, so before moving into the topic along with transmission impairment we will be

discussing the Reasons for Transmission Impairment.

So let’s move on to the topic now What Actually is transmission impairment?

We all know,

What is Transmission?

Transmission is sending of data from the sender to the receiver. While transmitting we use protocols.


What is Transmission Impairment?

Impairment is something which is called losing the date, abnormality, abnormal things or anything abnormal if it lost abnormally these are things which are called impairment.

What actually happens when we transfer data?

From the sender to the receiver the signal when we transfer the data or the signal it travels through a transmission medium it may be unguided or guided,

  • Guided means which involves cables of optical fibres those are guided medium.
  • Unguided medium is transferred through rays through-beam these type of transmission are unguided or Wi-Fi these are unguided transmission

So any, Type of Transmission Media through which signal travels and that medium is not perfect i.e it is not always what the sender sends and the receiver receives.

There may be some changes in the middle so the transmission medium is imperfect

The imperfection in the transmission medium is the causes of signal impairment.

This means what I want to say is the-

The signal at the beginning of the medium i.e the signal at the sender’s side is not the same as the signal at the end of the medium. It is not the same on the receiver side.  What is sent is slightly different from what is received.

There are Three Causes of Transmission Impairment

First transmission impairment-

As I said impairment means loss, abnormality or there are some changes in the function or structure. The first transmission impairment it deals with the loss of the signal.

Transmission Impairment

  1. Attenuation

  2. Distortion

  3. Noise

So the First Transmission Impairment is-

Attenuation in Transmission Impairments 


Attenuation is generally, it is a loss of energy means when a Simple Signal or a Composite Signal it travels through a medium from the sender side to the receiver. When the signal travels through a medium it loses some of its energy to overcome the resistance of the medium. so some energy must be lost as compared to the sender side and the receiver side.

This is what attenuation is. The example of this, we can notice electrical wire which carries the electricity which carries the signal it gets warm after some time. so that is the resistance in the wire that causes to warm. So the signal at the sender side would differ from the signal which is at the receiver side.

What actually happens is some of the energy in the electrical signal it is converted into heat i.e loss in energy.  The amplitude of the signal would go down.

In the case of attenuation, there is no change in the structure of the signal only energy is down, so what we have to do is we will put an amplifier to amplify the signal to compensate the loss of energy. This is why we use the amplifier.

Attenuation is one of the signal impairment.

so there is a measure for measuring the loss or gain of the signal and that measuring unit is

called the decibel. Decibel is written as DB

It measures the relative strength of two signal or one signal at two different points this is what the decibel do. In simple word, Decibel is used to compare the strength of two signals.

By comparing we can say whether some energy is lost or not

Now let’s move on to other impairment-


Distortion in Transmission Impairment

What is Transmission Impairment? , Distortion in Transmission Impairment
Distortion in Transmission Impairment

In attenuation, we are talking about the loss of energy.

In distortion, we will be talking about the change in the shape of the signal.

Distortion means the signal changes its forms or shapes, that the shape of this signal itself is changed.

Distortion generally occurs in the composite signal because of composite signals are made up of different frequencies.

Each signal component has its own propagation speed.

Suppose there is a component signal c1 which is made up of three different components so each signal each component signal would have a different frequency. So due to that, there may be a change in the shape of the signal that is known as distortion.

There is a difference in the delay for the sender to the receiver may differ in phase so this is called distortion. So you can see in this example these signal, the delay is different so the component may have some changes. So the original component signal is different and received one is different. This is what is called Distortion

Now the next Transmission Impairment is-

Noise in Transmission Impairment

Noise in Transmission Impairment, Types of Noises, Thermal Noise, Induced Noise, Cross Talk Noice, Impulse Noise, Signal To Noise Ratio, SNR.
Noise in Transmission Impairment

It is another cause of impairment there are several types of noises they are

  • Thermal Noise
  • Cross Talk

Suppose if you are communicating with your friends.

If you are talking on a mobile with your friend and someone else is talking behind you, so your friend would not be able to listen to you clearly.

So that is also a type of noise only – Cross Talks like this.

Types of Noises

  • One which takes place due to heat that is Thermal Noise
  • Induced Noise
  • Cross Talk Noice
  • Impulse Noise

These are the noises which may corrupt the signal

Noise is an external signal or external sound which make up the signal.

The first type of noise i.e  thermal noise

It is the random motion of electrons in a wire which creates an extra signal, not only transmitted by a transmitter.

So when we talk about thermal noise, suppose we have a sender and we have a receiver so there would be a transmission medium it is a guided transmission medium because of the heat generated by the resistance of the medium there would be some new signal generated which would interfere the original signal.

Induced Noise

This induced noises they come from sources that have motors and appliances etc.

Like external noise in your surrounding.

Cross Talk Noice


The third type of noise is crosstalk, The crosstalk is the effect of one wire on another.

Suppose there are two wires, both wires are interfering with the signal.

Let’s have an example

One act as a sending antenna whereas other receiver act as a receiving antenna so they would interfere in each other’s signal, so this is what crosstalk is.

So let’s see how

in the image is a signal which has to be sent there is a noise in the transmission medium due to resistance or due to thermal due to induced or due to crosstalk.

In the picture, you can see the received signal would be completely different from the same

signal so this is what noise is.

Signal To Noise Ratio

There is a term which is known as the signal-to-noise ratio that is (SNR) ratio it is very important.


ASP= Average Signal Power

ANP= Average Noise Power

It is a very important formula you can also, remember this as SNR i.e signal to noise ratio

So this is all about Transmission Impairment- Attenuation, Distortion, Noise and its type and formula.

Hope you like this what is transmission Impairment Attenuation Distortion Noise

Thank you


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