The document discusses noise in analog communication systems. It defines noise as an unwanted signal that affects the wanted signal. There are two main categories of noise: interference from human sources and naturally occurring random noise. Noise is generated internally in communication equipment and externally from environmental changes. Noise corrupts signals and degrades the signal-to-noise ratio, leading to bit errors in digital communication. The bit error rate and bit error probability are used to characterize the noise performance of a system. Additive noise is the combination of all noises added to the signal as it travels through the communication channel.

1. Institute of Information & Communication
Technology, University of Sindh
Assigned by
Engr Abdul Wahab*
To
Hafiz Muhammad Attaullah
2K18/TCT/23
attaullahshafiq10@gmail.com
Analog Communication
Presentation Topic:

2. Introduction:
Signals travel through transmission media, Experience
some fluctuation due to impurities of medium’s
materiel. The fluctuation causes signal impairment.
NOISE
Impairment
causes
Attenuation Distortion Noise
Attaullah Shafiq (2k18/TCT/23) IICT
University of Sindh
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3. NOISE
Noise is another cause of impairment.
• Noise is Described an unwanted signal which
effects a wanted signal.
• Noise in communication produce both in the
channel and communication equipment's.
• It may considered in one of two main categories.
i. Interference (usually from a human source “man made”).
ii. Naturally occurring random noise.
NOISE
Attaullah Shafiq (2k18/TCT/23) IICT
University of Sindh
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4. •This means that the signal at the beginning of the medium is not
the same as some noise factor produce in original signal and we get
a noisy signal at the reciever
NOISE
Attaullah Shafiq (2k18/TCT/23) IICT
University of Sindh
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5. NOISE
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University of Sindh
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6. Types of Noise:
Attaullah Shafiq (2k18/TCT/23) IICT
University of Sindh
NOISE
Noise
Internal
Noise
Thermal
Noise
Short Noise
Transit Time
Noise
External
Noise
Atmospheric
Noise
Extra
terrestrial
Noise
Man Made
Noise
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7. • Internal Noise
• It is generated in communication equipment that are
transmitter, medium, amplifier and receiver.
• It is produced in equipments.
Attaullah Shafiq (2k18/TCT/23) IICT
University of Sindh
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•Receptions
•Reproduction
NOISE
• External Noise
• It is generated by external sources(thermal
temperature or any other environmental changes).

8. When is noise Noise
NOISE
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University of Sindh
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9. Attaullah Shafiq (2k18/TCT/23) IICT
University of Sindh
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Origins of noise
NOISE
Attaullah Shafiq (2k18/TCT/23) IICT
University of Sindh
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•Electrical signal on a coaxial wire
•Optical signals on a fiber optics
•Electromagnetic signals through the air(wireless)

10. Effects of NOISE:
NOISE
Noise corrupts the signal.
Electrical noise can effects performance of the
system severely.
Attaullah Shafiq (2k18/TCT/23) IICT
University of Sindh
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11. SNR(Signal to Noise Ratio)
• It is the ratio of wanted signal to unwanted
signal(noisy signal).
Attaullah Shafiq (2k18/TCT/23) IICT
University of Sindh
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NOISE
•If SNR increase, signal will less corrupted by noise.
•If SNR will decrees, Signal will more corrupted by noise.

12. Bit Errors (Digital Signals)
Attaullah Shafiq (2k18/TCT/23) IICT
University of Sindh
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NOISE
Transmits bits of information from transmitter to Receiver:
1 0 0 1 1 1 0 1 0 0 0 (Bit Stream)
1 0 0 0 1 1 0 0 0 0 0 (Reception)
• Noise also disrupts the quality of communication in
digital signals b/w sender & receiver in the medium,
which causes a bit error.

13. Attaullah Shafiq (2k18/TCT/23) IICT
University of Sindh
13
Bit Errors (Digital Signals)
• Noise also disrupts the quality of communication in
digital signals b/w sender & receiver in the medium,
which causes a bit error.
Attaullah Shafiq (2k18/TCT/23) IICT
University of Sindh
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NOISE
Transmits bits of information from transmitter to Receiver:
1 0 0 1 1 1 0 1 0 0 0 (Bit Stream)
1 0 0 0 1 1 0 0 0 0 0 (Reception)
Bit error occur during the communication

14. Attaullah Shafiq (2k18/TCT/23) IICT
University of Sindh
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NOISE
Bit Error Rate(BER)
• Average rate of Bit Error is aka BER.
• We can say BER is the no. of bit error per unit
time/total number of transmitted bits
=
𝑁𝑜. 𝑜𝑓 𝑏𝑖𝑡 𝑒𝑟𝑟𝑜𝑟
𝑡𝑜𝑡𝑎𝑙 𝑛𝑜. 𝑜𝑓 𝑏𝑖𝑡𝑠 𝑡𝑟𝑎𝑛𝑠𝑚𝑖𝑡𝑡𝑒𝑑
• It can be employed to characterize the performance of a communication system.

15. Attaullah Shafiq (2k18/TCT/23) IICT
University of Sindh
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=
𝑁𝑜. 𝑜𝑓 𝑏𝑖𝑡 𝑒𝑟𝑟𝑜𝑟
𝑡𝑜𝑡𝑎𝑙 𝑛𝑜. 𝑜𝑓 𝑏𝑖𝑡𝑠 𝑡𝑟𝑎𝑛𝑠𝑚𝑖𝑡𝑡𝑒𝑑
NOISE
• For instance if 10,000 bits are transmitted, 100 bits are
received in error average BER
Example
=
100
10,000
= 0.01 𝑜𝑟 1%

16. Attaullah Shafiq (2k18/TCT/23) IICT
University of Sindh
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Bit Error Probabilities(Pe)
NOISE
• BER can also be expressed as a probability.
• Bit error probability(Pe) is the expectation value of
bit error ratio.
• Manually probability is b/w 0 & 1. but for the
probability of Bit Error is 0<=Pe<=0.5
• It means maximum BER=0.5

17. Attaullah Shafiq (2k18/TCT/23) IICT
University of Sindh
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Additive Noise:
• Additive noise is the sum of noises produce in
the signals, while travelling through the
medium.
NOISE
X→CHANNEL→𝑌𝑛𝑓(at medium) → Add NOISE→Y(at receiver)
𝑌𝑛𝑓[𝑛] =
𝑚=0
𝑚=𝑛
ℎ 𝑚 𝑥[𝑛 − 𝑚]
𝑌 𝑛 = 𝑌𝑛𝑓 𝑛 + 𝑛𝑜𝑖𝑠𝑒[𝑛] =
𝑚=0
𝑚=𝑛
ℎ 𝑚 𝑥[𝑛 − 𝑚] + 𝑛𝑜𝑖𝑠𝑒[𝑛]

18. Noise Statistics
Attaullah Shafiq (2k18/TCT/23) IICT
University of Sindh
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NOISE
𝜇 =
𝑛=0
𝑁−1
𝑛𝑜𝑖𝑠𝑒[𝑛]
𝑁
Noise Sampling mean
Noise of Variance
𝜎2 =
𝑛=0
𝑁−1
𝑛𝑜𝑖𝑠𝑒 𝑛 − 𝜇 2
𝑁

19. Any Questions
Attaullah Shafiq (2k18/TCT/23) IICT
University of Sindh
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NOISE
???