This document contains class notes on data communication. It summarizes the key differences between baseband and broadband transmission technologies. Baseband uses digital signals and supports bidirectional communication using two circuits. Broadband uses analog carrier waves and frequency division multiplexing to transmit multiple signals simultaneously. The document also discusses transmission impairments like attenuation, distortion, and noise that can degrade analog and cause bit errors in digital signals.

1. CITY UNIVERSITY
Department of Computer Science and Engineering
Class note
Course Title: Data Communication
Course Code: CSE 313
Submitted to:
PRANAB BANDHU NATH
Senior Lecturer
Dept. Of CSE
City University
Submitted By:
M. M. Shakhawat Ahammed
ID: 1834902106
Dept.: CSE
Submission Date:

2. Notes on Class 4.
Baseband: Baseband technology uses digital signals in data transmission. It sends binary values directly
as pulses of different voltage levels. Digital signals can be regenerated using repeaters in order to travel longer
distances before weakening and becoming unusable because of attenuation.
Baseband supports bidirectional communication. It means, this technology can send and receive data
simultaneously. To support bidirectional communication, this technology uses two separate electric circuits
together; one for sending and another for receiving.
Broadband: Broadband technology uses analog signals in data transmission. This technology uses a special
analog wave known as the carrier wave. A carrier wave does not contain any data but contains all properties
of the analog signal. This technology mixes data/digital signal/binary values into the carrier wave and sends
the carrier wave across the channel/medium.
To transmit data of multiple nodes simultaneously, this technology supports the Frequency Division
Multiplexing. FDM divides the channel into several sub-channels and assigns a sub-channel to each node.
Each sub-channel can carry a separate carrier wave.

3. Difference between baseband and broadband:
Baseband Broadband
Every device in the system share same channel Multiple channels can carry analog or digital
information through FDM.
Transmit digital signals Transmit analog signals
To boost signal strength, use repeaters To boost signal strength, use amplifiers
Can transmit only a single data stream at a time Can transmit multiple signal waves at a time
Support bidirectional communication
simultaneously
Support unidirectional communication only
Support TDM based multiplexing Support FDM based multiplexing
Use coaxial, twisted-pair, and fiber-optic cables Use radio waves, coaxial cables, and fiber optic
cables
Mainly used in Ethernet LAN networks Mainly used in cable and telephone networks

4. Transmission impairment:
When a signal transmit from one transmission medium to another, the signal that is received may differ from
the signal that is that is transmitted, due to various transmission impairments.
Consequences:
• For analog signals: degradation of signal quality.
• For digital signals: bit errors.
Types of transmission impairment:
• Attenuation
• Distortion
• Noise
Attenuation: Attenuation refers to the lose of data when it transmit one device to another device.
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.

5. 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 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.
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.

6. Reference:
Book: Data Communication and Networking By Behrouz A.Forouzan
Pictures:
https://www.computernetworkingnotes.com/networking-tutorials/differences-between-baseband-and-
broadband-explained.html
http://www.aviationchief.com/attenuation.html
https://www.geeksforgeeks.org/transmission-impairment-in-data-communication/
https://freeitnetwoking.blogspot.com/2017/02/what-is-transmission-impairments-with-its-types-full-explain-
with-diagrame-and-examples.html