Analog and Digital Communication Project

Overview

This repository contains the code and documentation for the Analog & Digital Communication Project submitted for the course Fundamental of Communication Systems (ECE 252). The project is divided into two main parts: Analog Communication and Digital Communication, focusing on signal processing, modulation, and demodulation techniques using Matlab.

The project was completed by:

• Amr Ahmed Wahidi
• Ammar Ahmed Wahidi
• Abdelrahman Essam Fahmy
• Mohamed Yehia Saeed
• Sobhey Mohamed Osman

Submitted to: Dr. Mazen Erfan, Dr. Alaa Fathy, Eng. Ahmed Al-Sayed, Eng. Ahmed Khaled
Submission Date: June 5th, 2025

Project Structure

The project is organized into two primary sections, each addressing different aspects of communication systems:

1. Analog Communication

This section focuses on the analysis, modulation, and transmission of analog signals using techniques such as:

• Signal generation and time-domain plotting.
• Fourier transform derivation and FFT computation.
• Bandwidth estimation based on power spectral density.
• Low-pass filtering (LPF) with bandwidths of 1 Hz and 0.3 Hz.
• Modulation schemes: DSB-SC (Double-Sideband Suppressed Carrier), SSB (Single Sideband, USB), and FDM (Frequency Division Multiplexing).
• Coherent detection for signal recovery.

Key tasks include:

• Plotting the function ( x(t) ) and its Fourier transform.
• Filtering and reconstructing signals.
• Implementing DSB-SC and SSB modulation with a 2 Hz guard band.
• Visualizing FDM signals and performing coherent demodulation.

2. Digital Communication

This section explores digital signal processing and modulation techniques, including:

• Line Coding: Implementation and comparison of Unipolar NRZ and Manchester coding for a 64-bit random stream.
• Binary Phase-Shift Keying (BPSK): Modulation and coherent demodulation of a random bit stream, including analysis of phase offsets (30°, 60°, 90°) and bit error rate (BER).

Key tasks include:

• Generating and visualizing coded signals in the time domain.
• Computing and plotting FFT and Power Spectral Density (PSD) for line codes.
• Implementing a BPSK transmitter and receiver, analyzing the spectrum, and evaluating performance under different phase conditions.

Repository Contents

• /analog: Contains Octave scripts for analog communication tasks, including signal plotting, Fourier transforms, filtering, and modulation (DSB-SC, SSB, FDM).
• /digital: Contains Octave scripts for digital communication tasks, including line coding (Unipolar NRZ, Manchester) and BPSK modulation/demodulation.
• /report: The project report (Communication Project Report.pdf) detailing the methodology, code, results, and analysis.

Prerequisites

To run the scripts in this repository, you need:

• MATLAB (or Octave) installed on your system.
• Basic understanding of signal processing and communication systems.

How to Run

1. Clone the repository:

   git clone https://github.com/Ammar-Wahidi/Analog_Digital-Communication-Project.git

2. Navigate to the analog or digital directory to access the respective scripts.
3. Open Octave and run the scripts (e.g., script_name.m) to execute the tasks and generate plots.
4. Refer to the project report (/report/Communication Project Report.pdf) for detailed explanations of each task and results.

Key Features

• Analog Communication:
  • Time-domain and frequency-domain analysis of signals.
  • Implementation of DSB-SC, SSB (USB), and FDM modulation schemes.
  • Bandwidth estimation and low-pass filtering.
  • Coherent detection for signal recovery.
• Digital Communication:
  • Comparison of Unipolar NRZ and Manchester line coding in time and frequency domains.
  • BPSK modulation and demodulation with phase offset analysis.
  • Visualization of signals, FFT, PSD, and bit error rates.

Results

• Analog Communication: Successfully plotted and analyzed signals, derived Fourier transforms, estimated bandwidth, and implemented modulation/demodulation schemes. The FDM scheme effectively combined DSB-SC and SSB signals with a 2 Hz guard band.
• Digital Communication: Demonstrated the differences between Unipolar NRZ and Manchester coding, highlighting Manchester’s superior clock recovery and DC balance. BPSK modulation showed robust performance, with zero bit errors at 30° and 60° phase offsets, but complete mismatch at 90° due to orthogonality.

References

• Introduction to Analog and Digital Communications by Simon Haykin and Michael Moher.