Fundamentals of Communication
Technology and Data
communications model
What is Data,Communication and Data Communication
Data
• Data is Raw facts and figures that need to be processed to become
meaningful.
• Can be text, numbers, images, audio, or video.
• Acts as the input for communication processes.
Communication
• Communication is the exchange of something (data) between two or
more devices.
• Can be wired (e.g., cables) or wireless (e.g., radio waves).
• To transfer data accurately and efficiently from sender to receiver.
Data Communication
● Data communications are exchange of data (bit) or information between
two devices via some form of transmission medium such as wire cable.
● It should be done in two ways
i) Local Communication- happens over short distances, typically
within a building or a small geographic area.It takes LAN Connection.
ii)Remote Communication-refers to data communication over longer
distances, typically across cities, regions, or even countries. It takes Long
distance like MAN & WAN.
● Data should be transferred in the form of 0’s and 1’
Data Communication Terminology
Channel-
● The term channel refers to a path of communications between two computers
or devices.
● Can be wired (like cables) or wireless (like radio waves).
● Example: Ethernet cables or Wi-Fi signals.
Baud-
● The number of signal changes (symbols) per second in a communication
channel.confused with bit rate, but baud rate measures how often the signal
changes, not the number of bits transmitted.
● Example: A baud rate of 1000 means 1000 signal changes per second.
(Bit rate measures the number of bits transmitted per second)
Signal-
signal is a representation of data that is transmitted from one device to
another over a communication medium. In data communication, signals
can be either analog or digital.
● Analog signals are continuous waves that vary over time,
● Digital signals are discrete, using binary (0s and 1s) to represent data,
Bandwidth-
● The maximum amount of data that can be transmitted over a channel in a given
time.(The bandwidth of a composite signal is the difference between the highest
and the lowest frequencies contained in that signal).
● Measured in bits per second (bps)or Hertz (Hz).
● Higher bandwidth means more data can be sent in less time.
Example: For digital devices, the bandwidth is usually expressed in bits per second
(bps) or bytes per second.
For analog devices, the bandwidth is expressed in cycles per second, or Hertz (Hz).
Bandwidth= f max- f min
Q: if a composite signal(signal have multiple sine waves) contains
frequencies between 1000 and 5000, its bandwidth is 5000 – 1000 =4000.
Q: What is the bandwidth of a composite signal that contains frequencies
between 1000 Hz and 5000 Hz?
Answer:
The bandwidth of the composite signal is 5000 Hz - 1000 Hz = 4000 Hz.
This represents the range of frequencies that the signal spans.
Frequency-
● Frequency is the number of cycles or
periods a signal completes within one
second. 1
● Measured in Hertz (Hz), where 1 Hz
equals one cycle per second.
● Higher frequency allows for more data to
be transmitted in a shorter time.
Wavelength: The distance between two consecutive compressions or two
consecutive rarefactions is known as the wavelength. Its SI unit is metre
(m).
Amplitude: The maximum height reached by the crest or trough of a sound
wave is called its amplitude.
Speed : How fast data moves from one point to another. unit is m/s-
meter per second
Period-
period refers to the time it takes for one complete cycle of a wave (signal) to pass a
given point. It is typically measured in seconds (s).
The period is the inverse of the frequency:
● Period (T) = 1 / Frequency (f)
f = frequency = number of waves produced by a source per second, in hertz Hz.
T = period = time it takes for one complete vibration or oscillation, in seconds s.
SI Units
Amplitude - meter (m)
Wavelength -meter (m)
-1
Frequency - Hertz (Hz)/per second (s )
-1
Period - Hertz (Hz )/Second (s)
-1
Speed - meters per second (ms )
This signal has an amplitude of 3mm and a wavelength of 4cm.
(measured, say, from crest to crest or trough to trough)
.
What is the frequency of the wave shown in below?
frequency is number of cycles a wave completes in one second.
In here 2 cycles complete in one second.
frequency= 2Hz
Exercises
1. What is the amplitude of
the solid (red) wave?
2. What is the wavelength
of the solid (red) wave?
3. How are the wavelengths
of the dashed (blue) and
dotted (green) waves
related?
Solutions:
1. The figure shows that the maximum positive disturbance of the solid (red)
wave from the x-axis is 1 cm, therefore the amplitude A = 1 cm
2. From the figure we see that the solid (red) wave has a full cycle between the
two points at x = 0 cm and x = 2 cm. Therefore, its wavelength λ = 2 cm
3. Comparing the cycles of the dashed (blue) and dotted (green) waves shown in
the figure, we see that the dashed wave cycle is twice as long as the dotted
one. The wavelengths λdashed and λdotted obey the relation:
λdashed = 2 × λdotted
A is the amplitude of the wave. The
time taken for a full cycle T is the
period of the wave.
The frequency (f) is the number of
cycles per second. It is given by:
1
f = 1 Hz
Frequency units: 1 cycle per second
is also called 1 Hertz (1Hz).
Period of this wave=
T=1/f
T=1/1
T= 1 Hz-1
Q: If the frequency of a wave is 4Hz, what is its period?
F=4 Hz
T=1/f
T=¼
-1
T=0.25 Hz or T=0.25 S
Q: If a sine wave completes 10 cycles in 2 seconds, what is its frequency?
Units of period and frequency
Q: A radio sound has a frequency of 10 kHz and a wavelength of
3.4 cm. What is its speed?
Q: A radio sound has a frequency of 3 MHz and a speed
of 300,000,000 m/s. What is its wavelength?
Q: A sound wave has a time period of 0.0001 seconds. What
is its frequency?
Q: A radio wave has a frequency of 3 MHz. What is
its period?
Q: A boat at sea bobs up and down as waves pass. The vertical distance
between a crest and a trough is 52 cm and 20 waves pass the boat in 30
seconds.
1. What is the amplitude of the waves?
2. What is the frequency of the waves?
Q; A microwave has a wavelength of 0.01m. What is the frequency of the wave?
8 -1
c=3∗10 ms
Answer
The velocity of a wave is equal to the product of the wavelength and frequency:
v=λf
We can rearrange this formula to solve for the frequency.
f=v/λ
Since microwaves are on the electromagnetic spectrum, their velocity will be equal to the speed of
light. We are given the wavelength. Using these values, we are able to solve for the frequency.
8 -1
f=3∗10 ms /0.01m
10
f=3∗10 Hz
1. Find the wavelength of a radio wave with a frequency of 650 kHz.
2. Find the wavelength of a radio wave with a frequency of 1300 kHz.
3. Find the wavelength of a radio wave with a frequency of 90 MHz.
4. Find the wavelength of a radio wave with a frequency of 101.5 MHz.
5. AM radio stations have frequencies from 540-1700 kHz.
a) Find the shortest wavelength AM radio signal.
b) Find the longest wavelength AM radio signal.
6. FM radio stations have frequencies from 88-108 MHz.
a) Find the longest wavelength FM radio signal.
b) Find the shortest wavelength FM radio signal.
Answers
1. 4.6 x 102 m (460 m)
2. 2.3 x 102 m (230 m)
3. 3.3 m
4. 2.96 m
5a. 1.76 x 102 m (176 m)
5b. 5.56 x 102 m (556 m)
6a. 3.4 m
6b. 2.8 m
Block Diagram for Communication Model
Transmission
Source Medium
Destination
● The effectiveness of a data communication system depend on 4
fundamental characteristics.
Characteristics of Communication Model
1) Delivery- The System must deliver the data to the correct
Destination.
2) Accuracy- The System must deliver the data at Accurate way.
3) Timeline - The System must deliver the data at Exact Time.
video conferencing, a delay or lag in data delivery can disrupt the flow of conversation, making real-time communication difficult. Timely delivery is
crucial for applications that rely on live or near-real-time data.
4) Jitter - It refers to the variable in the Perfect Arrival Time
Imagine you're having a video call. If the data (like your voice and video) doesn’t arrive smoothly and at regular intervals, you might experience:
Choppy audio (parts of your speech cut off or get delayed).
Distorted video (the picture might freeze or skip).
This happens because of jitter—the delay in the timing of how the data arrives.
Components of Communication Model
Block Diagram of Communication model
Components of Communication Model
i) Sender /Source/Transmitter
ii) Receiver / Destination
iii) Medium
iv) Message
v) Protocol
Components of Communication Model
1.) Sender : It is a device , that Sends the information to the
Receiver.It can be a Computer, workstation, telephone etc.
2.) Receiver : It is a device , that Receives the information
from the Sender.It can be a Computer, workstation,
telephone etc.
3.) Transmission Medium : It is the physical path or link
between Sender to Receiver.(physical path by which a
message travels from sender to receiver). Some examples
are twisted pair cable,coaxial cable, radio waves etc.
Components of Communication Model
4.) Message : This is the passing Informations. Popular
forms of information include text, pictures,audio,video etc.
5.) Protocols : It is a set of rules and regulations that “
Governed “ from data communication. It represented an
agreement between the communicating devices. two devices
may be connected but not communicating.
Data Representation and Transmission
❖ Data Transmission occurs between sender and receiver over
some Transmission Medium or Transmission Media.
• Transmission Media may be classified into Two Types :
i) Guided Media [Wired Technology]
ii) Unguided Media [Wireless Technology]
We already discussed in our 1 st part.
Data Representation
Signals
● A signal is a way to transmit information from one place to another.
● A signal is a representation of data in the form of electrical or
electromagnetic waves.
● Data itself can be analog such as human voice, or digital such as file on the
disk. Both analog and digital data can be represented in digital or analog
signals.
Data Representation
● To be transmitted, data must be transformed to electromagnetic
signals.
Topics discussed in this section:
● Analog and Digital Data
● Analog and Digital Signals
● Periodic and Nonperiodic Signals
Analog Data and Digital Data
● Analog data are continuous and take continuous values. ex : human
voice
● Digital data have discrete states and take discrete values.typically
binary (0s and 1s). ex: Text, images, and videos stored on a computer.
Difference Between Analog and Digital Signal (youtube.com)
Analog Signals and Digital Signals
1. Digital Signals
Digital signals are discrete in nature and represent sequence of voltage
pulses.
2. Analog Signals
Analog signals are in continuous wave form in nature and represented by
continuous electromagnetic waves.
Differences Between Analog and Digital Signal
Basis for
Analog Signal Digital Signal
Comparison
Basic An analog signal is a continuous wave that A digital signal is a discrete wave that
changes over a time period. carries information in binary form.
Representation An analog signal is represented by a sine A digital signal is represented by square
wave. waves.
Description An analog signal is described by the A digital signal is described by bit rate
amplitude, period or frequency, and phase. and bit intervals.
Range Analog signal has no fixed range. Digital signal has a finite numbers i.e. 0
and 1.
Distortion An analog signal is more prone to A digital signal is less prone to distortion.
distortion.
Transmit An analog signal transmit data in the form A digital signal carries data in the binary
of a wave. form i.e. 0 and 1.
Example The human voice is the best example of an Signals used for transmission in a
analog signal. computer are the digital signal.
Analog Signal
Analog vs. digital signals | Waves | Middle school physics | Khan Academy (youtube.com)
Periodic Signals and Nonperiodic Signals
● signal patterns based on their repetition over time.In data communications,
we commonly use periodic analog signals and non periodic digital signals.
Periodic Nonperiodic
A signal is said to be periodic signal Signal which does not at the
if it has a definite pattern and regular interval of time is
repeats itself at a regular known as an aperiodic signal or
interval of time.periodic signal non-periodic signal.
can be classified as simple or
composite. The simple Periodic
analog signal is sine wave.
Sine wave (simple periodic signal)
● The sine wave is the most fundamental form of a periodic analog signal.
● A sine wave can be represented by three parameters: the peak
amplitude, the frequency and the phase.
we already know about amplitude & frequency.
Amplitude Frequency & period
Phase
● Phase describes the position of the waveform relative to time 0.
● Measured in degrees (°) or radians.
● A complete cycle is 360° or 2π radians.
● Phase determines the timing of the wave, showing how one wave
aligns with another.
● A change in phase can shift the wave forward or backward in time.
A phase shift of 360° corresponds to a shift of a complete period.
A phase shift of 180° corresponds to a shift of one half of a period.
A phase shift of 90° corresponds to a shift of one quarter of a period.
Q: A sine wave is offset 1/6 cycle with respect to time 0.What is its
phase in degrees and radians?
Q: A sine wave is offset by 1/4 of a cycle with respect to time 0. What is
its phase in degrees and radians?
Amplitude, Wavelength & Phase Changing
Composite signals
● A composite periodic
analog signal is composed
of multiple sine waves
with different frequencies,
amplitude, and phases.
Digital Signal
Digital Signals
● Signal represents data as discrete values, typically in binary form (0s
and 1s)
● 1 represents high voltage (positive value) and 0 represents low
voltage(zero value).
● A digital signal can have more than two levels.In this case we can send
more than 1 bit for each level.
❏ Topics discussed in this section - Bit rate & Bit length
★ Bit Rate: A bit rate is measured as bits per second, the number of bits
send in 1 second.
Two digital signals: one with two signal levels and the other with four
signal levels
● 2 level signal
● 8 bits sent in 1
second
● bit rate=8 bps
● 4 level signal
● 16 bits sent in 1
second
● bit rate=16 bps
Q: A digital signal has eight levels. How many bits are needed per level? We
calculate the number of bits using following formula.
To determine how many bits are needed to represent a given number of
levels in a digital signal, you can use the formula:
if the signal have
2 levels - 1 bit
4 levels - 2 bits
8 levels - 3 bits
16 levels - 4 bits
32 levels - 5 bits
Bit rate=Number of bits/Time in seconds
Q: A digital signal transmits 5000 bits in 10 seconds. What is the bit rate of
this signal?
Question:
A digital communication system transmits 500,000 bits (including both 1s and 0s) over a duration of 10
seconds. Calculate the bit rate in bits per second (bps).
Answer:
Calculate the bit rate:
Bit rate (bps) = Total bits / Duration in seconds
Bit rate (bps) = 500,000 bits / 10 seconds = 50,000 bps
Question:
In a given transmission, 2,000,000 bits are sent over a period of 40 seconds. Out of these, 1,200,000 bits
are 1s. Calculate the bit rate in bits per second (bps).
Answer:
Calculate the bit rate (since bit rate is based on total bits transmitted):
Bit rate (bps) = Total bits / Duration in seconds
Bit rate (bps) = 2,000,000 bits / 40 seconds = 50,000 bps
Q: Assume we need to download text documents at the rate of 100 pages
per secoond. What is the required bit rate of the channel?
Assume that a page is an average of 24 lines with 80 characters in each line
and one character requires 8 bits.
Question:
Assume you need to download text documents at a rate of 50 pages per
second. Calculate the required bit rate of the channel.
Assumptions:
Each page contains an average of 30 lines.
Each line has 100 characters.
Each character requires 8 bits.
What is the required bit rate of the channel?
Bit length
● We discussed the concept of wavelength for analog signal.
● We can define something similar in digital signal is bit length.
● A bit length is the distance one bit occupies on the
transmission medium.
Bit length = propagation speed x bit duration
An analog signal is converted to a digital signal with a bit rate of 2000 bits
per second (bps). What is the bit length (time per bit) in this digital
representation of the analog signal?
-7
-7
3.33*10
-7-7
Types of network configurations or topologies
● Communication, is the process of sending information from a source to a
destination using any available mode like audio, video, signal, or even text.
● It could be simple, including only one sender and one receiver, or it could
involve several senders and receivers.
● how devices are connected and communicate with each other (based on
the number of senders and receivers in a communication) we can classify
02 ways.
1. Point-to-Point communication
2. Multi-Point communication
1. Point-to-Point communication
● A point-to-point connection is a direct link between two devices or nodes.also
known as P2P.
● There will be a transmitter and a receiver connected together with a suitable
connection. The capacity of the connecting channel remains unchanged throughout
the communication.
● A basic telephone call, in which one phone is connected to another, (one caller says
can only be heard by the other) and both nodes can send and receive audio, is the
most common example of point-to-point communication.
Key Characteristics:
Dedicated Link: The communication link is dedicated to the two connected devices.
Simple and Efficient: Since there are only two devices, managing the
communication is straightforward.
Limited to Two Devices: Only two devices can communicate over this link.
2. Multi-Point communication
● Point-to-multipoint communication is a form of one-to-many communication.
● Involves multiple devices sharing a single communication link. In this setup, several
devices are connected to the same network, and communication can be established
with any device on the network.
● A local area network (LAN) where multiple computers are connected to the same
network cable, or a bus network where many devices share the same communication
medium.
Key Characteristics:
Shared Link: Multiple devices use the same communication link, leading to shared
bandwidth.
Cost-Effective: Since many devices share the same connection, it reduces the need
for multiple links.
More Complex Management: Requires methods to manage the communication
between multiple devices ,
Difference between Point-to-Point and Multi-point Communication
Point-to-Point Multi-point Communication
the channel of communication is shared communication channel is shared among
only between two devices or nodes. multiple devices or nodes.
there is a dedicated link between two the link is shared between more than two
devices. devices.
The entire capacity of the channel is The capacity of the channel is temporarily
dedicated to the two connected devices. divided among the devices connecting to the
link.
single transmitter and a single receiver a single transmitter and multiple receivers are
are present. present.
more secure and private less secure than point-to-point
communication due to the larger number of
participants involved.
Modes of Data Transmission
Data can be transmitted from Source to Destination in a number of ways.
The different modes of data transmission will be outlined as follows:
● Parallel and Serial Communication.
● Asynchronous, Synchronous and Isochronous Communication.
● Simplex, Half duplex and Full duplex Communication.
Simplex, Half duplex and Full duplex Communication
1. Simplex Mode
● Sender can send the data but the sender unable receive the data. It is a type
of one way communication in which communication happens in only one
direction.
● Example of this kind of mode is Keyboard, Traditional Monitors,
Advantages & Disadvantages
Advantages Disadvantages
simple to implement because data incapacity to send data back in
travels in only one direction. the opposite way.
single directional,can be less not suitable for tasks requiring
costly response or acknowledgment,
data travels in only one direction, lack flexibility because they
there’s no risk of data collision, cannot be easily adjusted to
making the communication situations
secure and consistent.
Simplex, Half duplex and Full duplex Communication
2. Half duplex Mode
● Sender can send the data and also receive the data one sequentially.
● It is a bidirectional communication but limited to only one at a time.
● An example of this is the Walkie-Talkie,
Simplex, Half duplex and Full duplex Communication
2. Half duplex Mode
Advantages Disadvantages
allows for bidirectional data can only run in one direction
communication over a single at a time, communication is
channel naturally delayed
less complicated and less costly exchange between sending and
hardware than full-duplex receiving modes introduces delay,
systems
only one device can transmit at a require frequent two way
time, crashes are reduced, communication, half-duplex can
reducing the need for be less effective
complicated collision
Simplex, Half duplex and Full duplex Communication
3. Full duplex Mode
● Sender can send the data and also can receive the data simultaneously.
● It is dual way communication that is both way of communication happens
at a same time.
● Example of this kind of transmission is Telephone Network,
Simplex, Half duplex and Full duplex Communication
3. Full duplex Mode
Advantages Disadvantages
Data transfer is quicker because requires more complicated
there is no delaying for the hardware and can be more costly
channel to clear before sending or
receiving data.
more efficient because both demands a advanced quality of
directions of communication can architecture, such as better
occur at once. cabling and more refined
networking equipment,
Parallel and Serial Communication .
There are mainly two options for transmitting data, from the sender
to the receiver. These are:
● Serial communication.
● Parallel communication.
Serial Vs Parallel Transmission | Definition & Comparison Chart
(youtube.com)
Serial communication/ Serial transmission
● Data is transmitted one bit at a time, sequentially, over a single channel or wire.
● In Serial Transmission, 8 bits are sent at a time.
● Only one wire (or channel) is needed for data transmission.
● In serial transmission, data bits are sent one after the other across a single
channel.
● Because data is sent bit by bit, it may take longer for large data transfers.
● All long-distance communication and most computer networks employ serial
communication.
● Less chance of signal degradation.
Parallel Communication
● Parallel Communication sends many bits of data at the same time from
one computer to another
● Multiple bits are transmitted at once, speeding up (faster) data transfer.
● More wires are needed, which can be difficult to manage.
● Signal degradation and timing issues can occur over longer distances.
● Over longer distances, signals can get out of sync, leading to errors.
Difference between Serial and Parallel Transmission
Asynchronous vs Synchronous
● Asynchronous and Synchronous are two different methods of transmitting data.
These terms refer to how data is sent between devices in relation to timing and
synchronization.
● Both synchronous and asynchronous transmission, data is sent between the
transmitter and the receiver based on a clock pulse utilized for synchronization.
Synchronous transmission
● Data is sent in the form of blocks or frames.
● This transmission is the full-duplex type.
● Between sender and receiver, synchronization is compulsory.
● Both the sender and receiver are synchronized with a common clock signal. This
means they operate at the same speed and know exactly when to send and
receive data.
● There is no time gap present between data.
● It is more efficient and more reliable than asynchronous transmission to transfer
a large amount of data.
Asynchronous transmission
● Data is sent in form of byte or character at a time, with start and stop bits indicating
the beginning and end of each byte.
● This transmission is the half-duplex type transmission.
● It does not require synchronization.
● Each piece of data is sent independently.
● Asynchronous transmission is like sending individual text messages without
knowing exactly when the other person will read them.
Difference between Synchronous and Asynchronous Transmission
Synchronous Asynchronous
data is sent in form of blocks or frames. data is sent in form of bytes or characters
Synchronous transmission is fast. Asynchronous transmission is slow.
Synchronous transmission is costly. Asynchronous transmission is
economical.
there is no gap present between data. there is a gap present between data.
users have to wait till the transmission is users do not have to wait for the
complete before getting a response back completion of transmission in order to get
from the server. a response from the server.
Examples: Telephonic conversations, Examples: Email, File transfer,Online
Video conferencing, forms.
Transmission Impairments
When data is transmitted from a transmitter to receiver, there is scope for
transmission errors. If, transmission media were perfect, the receiver
would receive exactly the same signal that the transmitter sent.sometimes
not be the same as the transmitted signal.
❖ This means that the signal at the beginning of the medium is not the
same as the signal at the end of the medium
Transmission lines suffer from three major problems:
● Attenuation.
● Delay distortion.
● Noise.
Transmission Line Problems
1. Attenuation:
○ It means loss of energy.
○ The strength of signal decreases with increasing distance which causes loss of
energy in overcoming resistance of medium.
○ This is also known as attenuated signal.
○ Amplifiers are used to amplify the attenuated signal which gives the original
signal back and compensate for this loss.
2. Delay Distortion:
○ It means changes in the form or shape of the signal.
○ This is generally seen in composite signals made up with different frequencies.
○ Each frequency component has its own propagation speed travelling through a
medium.
○ And that's 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.
3 .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 intermodulation noise, crosstalk
noise, thermal noise and impulse noise which may corrupt the signal.
○ Intermodulation noise is when signals at different frequencies share the
same transmission medium, creating unwanted signals (interference) at
new frequencies.
○ Thermal noise is movement of electrons in wire which creates an extra
signal.
○ Crosstalk noise is when one wire affects the other wire.
○ Impulse noise is a signal with high energy that comes from lightning or
power lines
Thank you!
