dccn- physical layer
TRANSCRIPT
![Page 1: Dccn- Physical Layer](https://reader033.vdocuments.us/reader033/viewer/2022052514/5a65593c7f8b9a5b558b6fab/html5/thumbnails/1.jpg)
Data Communication and Computer Networks
[EEE 314]
Mubashir Husain RehmaniMubashir Husain Rehmani
Assistant Professor
Department of Electrical Engineering
COMSATS Institute of Information Technology,
Wah Cantt, Pakistan
![Page 2: Dccn- Physical Layer](https://reader033.vdocuments.us/reader033/viewer/2022052514/5a65593c7f8b9a5b558b6fab/html5/thumbnails/2.jpg)
Physical
Layer
![Page 3: Dccn- Physical Layer](https://reader033.vdocuments.us/reader033/viewer/2022052514/5a65593c7f8b9a5b558b6fab/html5/thumbnails/3.jpg)
Physical Layer
![Page 4: Dccn- Physical Layer](https://reader033.vdocuments.us/reader033/viewer/2022052514/5a65593c7f8b9a5b558b6fab/html5/thumbnails/4.jpg)
Duties of Physical Layer
![Page 5: Dccn- Physical Layer](https://reader033.vdocuments.us/reader033/viewer/2022052514/5a65593c7f8b9a5b558b6fab/html5/thumbnails/5.jpg)
Chapter 3 Signals
Chapter 4 Digital Transmission
Chapter 5 Analog Transmission
Chapter 6 Multiplexing
Chapter 7 Transmission Media
Chapter 8 Circuit Switching and Telephone Network
Chapter 9 High Speed Digital Access
![Page 6: Dccn- Physical Layer](https://reader033.vdocuments.us/reader033/viewer/2022052514/5a65593c7f8b9a5b558b6fab/html5/thumbnails/6.jpg)
Signals
![Page 7: Dccn- Physical Layer](https://reader033.vdocuments.us/reader033/viewer/2022052514/5a65593c7f8b9a5b558b6fab/html5/thumbnails/7.jpg)
To be transmitted, data must be
transformed to electromagnetic signals.
![Page 8: Dccn- Physical Layer](https://reader033.vdocuments.us/reader033/viewer/2022052514/5a65593c7f8b9a5b558b6fab/html5/thumbnails/8.jpg)
Analog and Digital Data
Analog and Digital SignalsAnalog and Digital Signals
Periodic and Aperiodic Signals
![Page 9: Dccn- Physical Layer](https://reader033.vdocuments.us/reader033/viewer/2022052514/5a65593c7f8b9a5b558b6fab/html5/thumbnails/9.jpg)
Signals can be analog or digital.
Analog signals can have an infinite
number of values in a range; digital number of values in a range; digital
signals can have only a limited number
of values.
![Page 10: Dccn- Physical Layer](https://reader033.vdocuments.us/reader033/viewer/2022052514/5a65593c7f8b9a5b558b6fab/html5/thumbnails/10.jpg)
Comparison of Analog and
Digital Signal
![Page 11: Dccn- Physical Layer](https://reader033.vdocuments.us/reader033/viewer/2022052514/5a65593c7f8b9a5b558b6fab/html5/thumbnails/11.jpg)
In data communication, we commonly
use periodic analog signals and
aperiodic digital signals.aperiodic digital signals.
![Page 12: Dccn- Physical Layer](https://reader033.vdocuments.us/reader033/viewer/2022052514/5a65593c7f8b9a5b558b6fab/html5/thumbnails/12.jpg)
Analog Signals
Sine Wave
Phase
Examples of Sine WavesExamples of Sine Waves
Time and Frequency Domains
Composite Signals
Bandwidth
![Page 13: Dccn- Physical Layer](https://reader033.vdocuments.us/reader033/viewer/2022052514/5a65593c7f8b9a5b558b6fab/html5/thumbnails/13.jpg)
A Sine Wave
![Page 14: Dccn- Physical Layer](https://reader033.vdocuments.us/reader033/viewer/2022052514/5a65593c7f8b9a5b558b6fab/html5/thumbnails/14.jpg)
Amplitude
![Page 15: Dccn- Physical Layer](https://reader033.vdocuments.us/reader033/viewer/2022052514/5a65593c7f8b9a5b558b6fab/html5/thumbnails/15.jpg)
Frequency and period are inverses of
each other.
![Page 16: Dccn- Physical Layer](https://reader033.vdocuments.us/reader033/viewer/2022052514/5a65593c7f8b9a5b558b6fab/html5/thumbnails/16.jpg)
Period and Frequency
![Page 17: Dccn- Physical Layer](https://reader033.vdocuments.us/reader033/viewer/2022052514/5a65593c7f8b9a5b558b6fab/html5/thumbnails/17.jpg)
Units Units of periods and frequenciesof periods and frequencies
Unit Equivalent Unit Equivalent
Seconds (s) 1 s hertz (Hz) 1 Hz
Milliseconds (ms) 10–3 s kilohertz (KHz) 103 Hz
Microseconds (ms) 10–6 s megahertz (MHz) 106 Hz
Nanoseconds (ns) 10–9 s gigahertz (GHz) 109 Hz
Picoseconds (ps) 10–12 s terahertz (THz) 1012 Hz
![Page 18: Dccn- Physical Layer](https://reader033.vdocuments.us/reader033/viewer/2022052514/5a65593c7f8b9a5b558b6fab/html5/thumbnails/18.jpg)
Frequency is the rate of change with
respect to time. Change in a short span
of time means high frequency. Change of time means high frequency. Change
over a long span of time means low
frequency.
![Page 19: Dccn- Physical Layer](https://reader033.vdocuments.us/reader033/viewer/2022052514/5a65593c7f8b9a5b558b6fab/html5/thumbnails/19.jpg)
If a signal does not change at all, its
frequency is zero. If a signal changes
instantaneously, its frequency is infinite.instantaneously, its frequency is infinite.
![Page 20: Dccn- Physical Layer](https://reader033.vdocuments.us/reader033/viewer/2022052514/5a65593c7f8b9a5b558b6fab/html5/thumbnails/20.jpg)
Phases
![Page 21: Dccn- Physical Layer](https://reader033.vdocuments.us/reader033/viewer/2022052514/5a65593c7f8b9a5b558b6fab/html5/thumbnails/21.jpg)
Time and Frequency Domain
![Page 22: Dccn- Physical Layer](https://reader033.vdocuments.us/reader033/viewer/2022052514/5a65593c7f8b9a5b558b6fab/html5/thumbnails/22.jpg)
Time and Frequency Domain
![Page 23: Dccn- Physical Layer](https://reader033.vdocuments.us/reader033/viewer/2022052514/5a65593c7f8b9a5b558b6fab/html5/thumbnails/23.jpg)
Time and Frequency Domain
![Page 24: Dccn- Physical Layer](https://reader033.vdocuments.us/reader033/viewer/2022052514/5a65593c7f8b9a5b558b6fab/html5/thumbnails/24.jpg)
A single-frequency sine wave is not
useful in data communications; we need
to change one or more of its to change one or more of its
characteristics to make it useful.
![Page 25: Dccn- Physical Layer](https://reader033.vdocuments.us/reader033/viewer/2022052514/5a65593c7f8b9a5b558b6fab/html5/thumbnails/25.jpg)
When we change one or more When we change one or more
characteristics of a singlecharacteristics of a single--frequency frequency
signal, it becomes a composite signal signal, it becomes a composite signal signal, it becomes a composite signal signal, it becomes a composite signal
made of many frequencies.made of many frequencies.
![Page 26: Dccn- Physical Layer](https://reader033.vdocuments.us/reader033/viewer/2022052514/5a65593c7f8b9a5b558b6fab/html5/thumbnails/26.jpg)
According to Fourier analysis, any
composite signal can be represented as
a combination of simple sine waves a combination of simple sine waves
with different frequencies, phases, and
amplitudes.
![Page 27: Dccn- Physical Layer](https://reader033.vdocuments.us/reader033/viewer/2022052514/5a65593c7f8b9a5b558b6fab/html5/thumbnails/27.jpg)
Square Wave
![Page 28: Dccn- Physical Layer](https://reader033.vdocuments.us/reader033/viewer/2022052514/5a65593c7f8b9a5b558b6fab/html5/thumbnails/28.jpg)
Signal Corruption
![Page 29: Dccn- Physical Layer](https://reader033.vdocuments.us/reader033/viewer/2022052514/5a65593c7f8b9a5b558b6fab/html5/thumbnails/29.jpg)
Bandwidth
The bandwidth is a property of a The bandwidth is a property of a
medium: It is the difference between the medium: It is the difference between the
highest and the lowest frequencies that highest and the lowest frequencies that highest and the lowest frequencies that highest and the lowest frequencies that
the medium can the medium can
satisfactorily pass.satisfactorily pass.
![Page 30: Dccn- Physical Layer](https://reader033.vdocuments.us/reader033/viewer/2022052514/5a65593c7f8b9a5b558b6fab/html5/thumbnails/30.jpg)
Bandwidth
![Page 31: Dccn- Physical Layer](https://reader033.vdocuments.us/reader033/viewer/2022052514/5a65593c7f8b9a5b558b6fab/html5/thumbnails/31.jpg)
![Page 32: Dccn- Physical Layer](https://reader033.vdocuments.us/reader033/viewer/2022052514/5a65593c7f8b9a5b558b6fab/html5/thumbnails/32.jpg)
Example 4Example 4
A signal has a bandwidth of 20 Hz. The highest frequency
is 60 Hz. What is the lowest frequency? Draw the
spectrum if the signal contains all integral frequencies of
the same amplitude.
SolutionSolutionSolutionSolution
B = B = ffhh −− ffll
20 = 60 20 = 60 −− ffll
ffll = 60 = 60 −− 20 = 40 Hz20 = 40 Hz
![Page 33: Dccn- Physical Layer](https://reader033.vdocuments.us/reader033/viewer/2022052514/5a65593c7f8b9a5b558b6fab/html5/thumbnails/33.jpg)
![Page 34: Dccn- Physical Layer](https://reader033.vdocuments.us/reader033/viewer/2022052514/5a65593c7f8b9a5b558b6fab/html5/thumbnails/34.jpg)
Digital Signal
Bit Interval and Bit Rate
As a Composite Analog Signal
Through Wide-Bandwidth MediumThrough Wide-Bandwidth Medium
Through Band-Limited Medium
Versus Analog Bandwidth
Higher Bit Rate
![Page 35: Dccn- Physical Layer](https://reader033.vdocuments.us/reader033/viewer/2022052514/5a65593c7f8b9a5b558b6fab/html5/thumbnails/35.jpg)
A Digital Signal
![Page 36: Dccn- Physical Layer](https://reader033.vdocuments.us/reader033/viewer/2022052514/5a65593c7f8b9a5b558b6fab/html5/thumbnails/36.jpg)
Example 6Example 6
A digital signal has a bit rate of 2000 bps. What is the
duration of each bit (bit interval)
SolutionSolution
The bit interval is the inverse of the bit rate.
Bit interval = 1/ 2000 s = 0.000500 s
= 0.000500 x 106 µs = 500 µs
![Page 37: Dccn- Physical Layer](https://reader033.vdocuments.us/reader033/viewer/2022052514/5a65593c7f8b9a5b558b6fab/html5/thumbnails/37.jpg)
Bit Rate and Bit Interval
![Page 38: Dccn- Physical Layer](https://reader033.vdocuments.us/reader033/viewer/2022052514/5a65593c7f8b9a5b558b6fab/html5/thumbnails/38.jpg)
![Page 39: Dccn- Physical Layer](https://reader033.vdocuments.us/reader033/viewer/2022052514/5a65593c7f8b9a5b558b6fab/html5/thumbnails/39.jpg)
The bit rate and the bandwidth are The bit rate and the bandwidth are
proportional to each other.proportional to each other.
![Page 40: Dccn- Physical Layer](https://reader033.vdocuments.us/reader033/viewer/2022052514/5a65593c7f8b9a5b558b6fab/html5/thumbnails/40.jpg)
Baseband transmission Baseband transmission means sending a means sending a
digital signal over a channel without changing digital signal over a channel without changing
the digital signal to analog form.the digital signal to analog form.
Baseband transmission requires that we have Baseband transmission requires that we have
a lowa low--pass channel. pass channel.
A lowA low--pass channel pass channel �� bandwidth that starts bandwidth that starts
from zero.from zero.
![Page 41: Dccn- Physical Layer](https://reader033.vdocuments.us/reader033/viewer/2022052514/5a65593c7f8b9a5b558b6fab/html5/thumbnails/41.jpg)
Broadband transmission or ModulationBroadband transmission or Modulation
means sending a digital signal over a channel means sending a digital signal over a channel
by changing the digital signal to analog form.by changing the digital signal to analog form.
Broadband transmission requires that we have Broadband transmission requires that we have Broadband transmission requires that we have Broadband transmission requires that we have
a banda band--pass channel. pass channel.
A bandA band--pass channel pass channel �� bandwidth that does bandwidth that does
not starts from zero.not starts from zero.
![Page 42: Dccn- Physical Layer](https://reader033.vdocuments.us/reader033/viewer/2022052514/5a65593c7f8b9a5b558b6fab/html5/thumbnails/42.jpg)
Low-Pass and Band-Pass
Channel
![Page 43: Dccn- Physical Layer](https://reader033.vdocuments.us/reader033/viewer/2022052514/5a65593c7f8b9a5b558b6fab/html5/thumbnails/43.jpg)
Transmission Impairments
![Page 44: Dccn- Physical Layer](https://reader033.vdocuments.us/reader033/viewer/2022052514/5a65593c7f8b9a5b558b6fab/html5/thumbnails/44.jpg)
Attenuation
![Page 45: Dccn- Physical Layer](https://reader033.vdocuments.us/reader033/viewer/2022052514/5a65593c7f8b9a5b558b6fab/html5/thumbnails/45.jpg)
Distortion
![Page 46: Dccn- Physical Layer](https://reader033.vdocuments.us/reader033/viewer/2022052514/5a65593c7f8b9a5b558b6fab/html5/thumbnails/46.jpg)
Noise
![Page 47: Dccn- Physical Layer](https://reader033.vdocuments.us/reader033/viewer/2022052514/5a65593c7f8b9a5b558b6fab/html5/thumbnails/47.jpg)
Throughput
![Page 48: Dccn- Physical Layer](https://reader033.vdocuments.us/reader033/viewer/2022052514/5a65593c7f8b9a5b558b6fab/html5/thumbnails/48.jpg)
Propagation Time