UNIVERSITY OF WEST ATTICA
SCHOOL OF ENGINEERING
DEPARTMENT OF COMPUTER ENGINEERING AND INFORMATICS

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Signals and Systems

Analog Signals

Vasileios Evangelos Athanasiou
Student ID: 19390005

GitHub · LinkedIn

Supervisor: Adonis Bogris, Professor

UNIWA Profile · LinkedIn

Co-supervisor: Georgios Antoniou, Laboratory Teaching Staff

UNIWA Profile

Athens, April 2021

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Analog Signals - Laboratory Task

This README provides an overview of the Analog Signals laboratory task completed for the Signals and Systems course at the University of West Attica.

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Table of Contents

Section	Folder/File	Description
1	assign/	Assignment instructions and exercise description
1.1	assign/EXERCISE 2 - ANALOG SIGNALS.pdf	Exercise instructions (English)
1.2	assign/ΑΣΚΗΣΗ 2 - ΑΝΑΛΟΓΙΚΑ ΣΗΜΑΤΑ.pdf	Exercise instructions (Greek)
2	docs/	Documentation related to analog signals exercises
2.1	docs/Analog-Signals.pdf	Analog signals documentation (English)
2.2	docs/Αναλογικά-Σήματα.pdf	Analog signals documentation (Greek)
3	src/	MATLAB source code files for analog signals exercises
3.1	src/b1.m	MATLAB script file
3.2	src/b2.m	MATLAB script file
3.3	src/b3.m	MATLAB script file
3.4	src/b4.m	MATLAB script file
3.5	src/b5.m	MATLAB script file
3.6	src/b6.m	MATLAB script file
3.7	src/b7.m	MATLAB script file
3.8	src/b8.m	MATLAB script file
4	README.md	Repository overview and usage instructions

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Exercises Summary

Exercise 1: Step Function Signal Generation

The objective was to plot the signal:

$$ x(t) = u(t+1) - u(t-2) + u(t-4) $$

Two approaches were used:

Manual Method

• Interval [-5, 10] divided into subintervals.
• Arrays of zeros and ones manually constructed to model the signal behavior.

Heaviside Method

• MATLAB’s built-in heaviside function was used to efficiently construct and plot the signal.

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Exercise 2: Modulated Sinusoidal Signal

Plotting a sinusoidal signal modulated by both a ramp and a time window.

Signal definition:

[ x(t) = t \sin(2\pi t),(u(t) - u(t-3)) ]

Implementation details

• Time interval: [0, 3]
• Window generated using the square pulse

$$ u(t) - u(t-3) $$

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Exercise 3: Pulsed Oscillatory Signal

Visualization of a cosine oscillation within a limited pulse duration.

Signal:

$$ x(t) = t^3 \cos(10\pi t),p_2(t-1) $$

Where the square pulse is defined as:

$$ p_2(t-1) = u(t) - u(t-2) $$

representing a pulse duration of T = 2.

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Exercise 4: Unit Step Summation

Signal expression derived from a provided graphical representation:

$$ x(t) = u(t) - u(t-1) - u(t-2) $$

The signal was plotted over:

$$ [-2, 3] $$

to reproduce the original waveform characteristics.

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Exercise 5: Signal Decomposition (Even & Odd Parts)

Analysis of signal symmetry components.

Original signal:

$$ x(t) = t e^{-t}, \quad 0 \le t \le 5 $$

Components computed:

• Original signal
• Even component
• Odd component
• Reconstruction (even + odd)

Displayed using MATLAB's subplot function in a 2×2 grid.

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Technical Functions Used

Function	Purpose
heaviside(t)	Computes unit step function
zeros() / ones()	Creates arrays for manual signal construction
plot(t, x)	Generates signal plots
ylim([min, max])	Controls plot vertical limits
subplot(m, n, p)	Displays multiple plots in one figure

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Summary

The laboratory task demonstrated practical implementation of step functions, windowed signals, oscillatory signals, and signal decomposition techniques using MATLAB visualization tools for analog signal analysis.

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Installation & Setup Guide

This guide explains how to install requirements and run the MATLAB exercises contained in this repository.

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1. Prerequisites

To run the project, you need:

• MATLAB installed on your system
  (Any recent version should work; recommended R2020 or newer)
• Basic familiarity with MATLAB scripts and workspace execution

Optional:

• Git (to clone the repository)

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2. Obtain the Project

Option A — Clone Repository (Recommended)

Open a terminal or command prompt and run:

git clone https://github.com/Signals-and-Systems-aka-Uniwa/Analog-Signals.git

Option B — Download ZIP

1. Open the repository page in your browser.
2. Click Code → Download ZIP.
3. Extract the archive to a folder on your computer.

3. Open Project in MATLAB

1. Start MATLAB.
2. Click Home → Set Path → Add Folder or:
   • Use Set Current Folder in MATLAB.
3. Navigate to the repository folder.
4. Open the src/ directory.

Recommended folder:

Analog-Signals/src/

4. Running the Scripts

Each exercise is implemented as MATLAB scripts. From MATLAB:

Method 1 — Double Click

Double-click any script:

b1.m
b2.m
b3.m
b4.m
b5.m
b6.m
b7.m
b8.m

and press Run.

Method 2 — Command Window

Run scripts directly:

b1
b2
b3
b4
b5
b6
b7
b8

5. Required MATLAB Functions

Scripts rely on standard MATLAB functions such as:

• heaviside
• plot
• subplot
• zeros, ones
• ylim

No external toolboxes are typically required beyond standard MATLAB functionality.

6. Expected Output

Running scripts will generate:

• Analog signal plots
• Windowed signals
• Oscillatory signals
• Signal decomposition plots
• Multiple subplot figures
• Plots appear automatically in MATLAB figure windows.

7. Common Issues & Fixes

Script Not Found

Ensure MATLAB current folder is:

Analog-Signals/src/

Function Undefined Error

Add folder to MATLAB path:

addpath(genpath(pwd))

Plot Not Displayed

Ensure script execution completed without errors and figure windows are not hidden.