This document provides an overview of data communication concepts including analog vs digital signals, fiber optic cables, and different types of digital modulation techniques such as ASK, FSK, and PSK. It was submitted by Md. Ismail as an assignment for the course Data Communication with course code CSE 313 at City University. The submission date was September 1, 2021.

1. Assignment
On
4th
class note
Course title : Data communication
Course code : CSE 313
Submitted to
Pranab bandhu nath
Senior Lecturer
Department of CSE
City University
Submitted by
Md.ismail
Id: 1834902082
Batch : 49th
(B)
Department of CSE
City University
Submission date : 01.09.2021

2. when data is sent over physical medium it means to first cover in to electro magnetic
signals.Data itself can be converted into signals block type data transfer.
Signal
Analog signal digital signal
Analog signal
An analog signal is time-varying and generally bound to a range but there is an infinite number
of values within that continuous range.For example human voice.
Digital signal
A digital signal is a signal that represents data as a sequence of discrete values. A digital signal
can only take on one value from a finite set of possible values at a given time.For example
document on a disk.
Fiber optic cable
A fiber optic cable is a network cable that contains strands of glass fibers inside an insulated
casing.
Digital modulation
Modulation is the process of converting data into radio waves by adding information to an
electronic or optical carrier signal.
The simplest modulation, a type of unipolar encoding, is simply to switch on and off a DC signal
so that high voltages represent a '1' and low voltages are '0'.
Digital modulation
ASK FSK PSK
ASK(Amplitude shift keying)

3. ASK refers to a type of amplitude modulation that assigns bit values to discrete amplitude levels.
It transfer signal using fiber optic cable .
FSK
FSK refers to a type of frequency modulation that assigns bit values to discrete frequency levels.
It transfer signal using coaxial cable.
High frequency - 1
Low frequency - 0
Phase-shift keying (PSK)
Phase-shift keying (PSK) is a digital modulation process which conveys data by changing
(modulating) the phase of a constant frequency reference signal (the carrier wave).
It transfer signal using router or brouter
Reference : https://www.monolithicpower.com/en/analog-vs-digital-signal