In this slide we discuss about following topics: 1: TRANSMISSION IMPAIRMENT 2: Causes of Transmission impairment 3: Attenuation 4: Amplifiers and Repeater/Regenerator: 5: Decibel (dB) 6: Distortion 7: Noise 8: Types of Noise: ( Thermal noise, induced noise, Crosstalk, impulse noise) 9: Signal-to-Noise Ratio (SNR)

1. TRANSMISSION IMPAIRMENT
Lecture 8
Date: 15-10-2020

2. TRANSMISSION IMPAIRMENT:
▪ The (loss of energy) difference of energy and power of signal
from sender to receiver.
▪ It means that signals that are transmitted at the beginning of
the medium are not the same as the signals that are received
at the end of the medium that is what is sent is not what is
received.
▪ When a signal transmit from one transmission medium to
other, the signal that is received may differ from the signal
that is transmitted, due to various transmission impairments.

3. Causes of Transmission impairment:
▪ There are three types (Causes) of transmission impairments:
 Attenuation
 Distortion (Delay distortion)
 Noise

4. Attenuation:
▪ Attenuation means a loss of energy.When a signal, simple or
composite, travels through a medium, it loses some of its energy in
overcoming the resistance of the medium.
▪ That is why a wire carrying electric signals gets warm, if not hot, after a
while. Some of the electrical energy in the signal is converted to heat.
▪ To compensate for this loss, amplifiers are used to amplify the signal.

5. Amplifiers and Repeater/ReGenerater:
▪ Amplifiers: are used to amplify
the attenuated signal which
gives the original signal back and
compensate for this loss.
▪ Amplifier: is use to strong the
signal. we use Amplifier to travel
the signal to a long distance.
▪ In telecommunications,
a Repeater/ReGenerater is an
electronic device that receives
a signal and retransmits it.
Repeaters are used to extend
transmissions so that the signal can
cover longer distances or be
received on the other side of an
obstruction.

6. Attenuation:

7. Decibel (dB):
▪ The decibel (dB) measures the relative strengths of two signals or
one signal at two different points.
▪ To show that a signal has lost or gained strength, engineers use the
unit of the decibel.
▪ Note that the decibel is negative if a signal is attenuated and positive
if a signal is amplified.
▪ Attenuation(dB) = 10log10(P2/P1)
▪ P1 is the power at sending end and P2 is the power at receiving end.

8. Decibel (dB):
▪ A unit that is used for the measurement of Strength and
weakness of a signal.
important points:
▪ If the value of dB is greater then 1 it means signal is
strong.
▪ If the value of dB is less then 1 it means signal is week.
▪ If the value of dB is equal to 1 it means signal is same.

9. Distortion:
▪ Distortion means that the signal changes its form or shape.
▪ Distortion can occur in a composite signal made of different frequencies. Each
frequency component has its own propagation speed travelling through a
medium. And thats why it delay in arriving at the final destination Every
component arrive at different time which leads to distortion.Therefore, they
have different phases at receiver end from what they had at senders end.
▪ “The difference in delay may cause face or shape difference of a composite
signal, it is called distortion”.

10. Distortion:

11. Noise:
▪ Noise –The random or unwanted signal that mixes up with the
original signal is called Noise.
▪ There are several types of noise such as induced noise, crosstalk
noise, thermal noise and impulse noise which may corrupt the
signal. Induced noise comes from sources such as motors and
appliances.
▪ There are several types of noise as: thermal noise, induced noise,
crosstalk, and impulse noise

12. Noise:

13. Types of Noise:
▪ Thermal noise
▪ induced noise
▪ Crosstalk
▪ impulse noise

14. Thermal Noise:
▪ Thermal noise is cause due to the existence of high power
device generate high power speed movement of electrons
in a wire.
▪ Thermal noise is movement of electrons in wire which
creates an extra signal.
▪ Note : wire is heat up due to thermal noise.

15. Induced Noise:
▪ This noise is cause due to induction caused by high
power sources.
▪ Induced noise comes from sources such as motors
and appliances.

16. Crosstalk:
▪ Crosstalk noise is when one wire affects the other
wire.
▪ One wire acts as a sending antenna and the other as
the receiving antenna.

17. impulse Noise:
▪ It cause due to spike that comes from power lines,
lightning, and so on.
▪ Spike : A signal with high energy in a very short
time.

18. Signal-to-Noise Ratio (SNR):
▪ It is the ratio between average power in single over average power of
noise.
▪ SNR = AVG SIGNAL POWER / AVG NOISE POWER
▪ SNR is actually the ratio of what is wanted (signal) to what is not wanted
(noise).
▪ A high SNR means the signal is less corrupted by noise and A low SNR
means the signal is more corrupted by noise.
▪ Because SNR is the ratio of two powers, it is often described in decibel
units,
▪ SNRdB, defined as SNRcm = l0 loglo SNR

19. Thank You my dear!
Regards: MuhammadAwais (University: kfueit)
For any mistake in slide please tell me at chawais2001@gmail.com