Skip to content

Latest commit

 

History

History
366 lines (296 loc) · 10.3 KB

Readme.md

File metadata and controls

366 lines (296 loc) · 10.3 KB

SAMA3NY

"Don't Worry, Your Message Will Be Sent 🔊"

Table of Contents

Overview

  • It is required to modulate three speech signals using the following scheme:


    and then perform synchronous demodulation.

  • Then do the following operation:

    1. Obtain the modulated signal. Plot it in time domain. Plot its magnitude spectrum
    2. Perform synchronous demodulation to restore the three signals.
    3. Perform demodulation three times with phase shifts of 10, 30, 90 degrees for both carriers.
    4. For x_1 (t), perform demodulation two times with a local carrier frequency that is different by 2 Hz and 10 Hz from its carrier frequency.
  • Project Description

Get Started

  1. Clone the repository. 
    git clone https://github.com/ZiadSheriif/SAMA3NY
  2. Put Inputs in folder 

    3. cd ./signals
  3. Run File

    4. cd ./project.m
  4. Output will be in folder 

    5. cd ./Output_signals

Work Explanation

Input signals

Firstly, we read three signals with different sounds and make them have the same frequency sampling =250000 by make resemble to them and find the length of each one along with max length in-order to be able to sum all modulated signal of each input. We make all audios have the same length by adjusting all of them by adding zero to make have same length. Secondly got time and frequencies intervals. Then we calculated omega (ω1, ω2) by ω=2piconst in frequency domain. Then we got carrier in cos and sin domain Carrier Signal One=cos (2pi ω1) Carrier Signal Two=sin (2pi ω2)


Signal 1
Signal 2
Signal 3

Modulated signal:

  1. Calculate modulated signal by multiplying signal and carrier
  2. Calculate Fourier transform of modulated signal returned from step 1
  3. Calculate phase of modulated signal returned from step 1
  4. Sum all modulated signals of all audios
  5. FFT to summation of modulated signals
  6. Calculate phase of modulated signals
  7. Calculate frequency band pass which is used in de-modulation

De-modulation:

  1. Calculate demodulated signal by multiplying carrier and modulation signal
  2. Calculate low pass filter used frequency sampling.
  3. Perform demodulation three times with phase shifts of 10, 30, 90 degrees for both carriers

    Note: (before each phase shift calculate carrier phase).

  4. Perform demodulation two times with a local carrier frequency that is different by 2 Hz and 10 Hz from its carrier frequency.

💻 Demodulation with phase shift 10:

Note: Interference in sounds between signal 2 and signal 3 when make demodulation to them. Signal 1 become little weaker.

💻 Demodulation with phase shift 30:

Note: More Interference in sounds between signal 2 and signal 3 when make demodulation to them. Signal 1 become Weaker.

💻 Demodulation with phase shift 90:

Note: When make demodulation to signal 3 output is signal 2 and make demodulation to signal 2 output is signal3 Signal 1 be equal zero (no sound).

💻 Demodulation with a local carrier frequency that is different by 2 Hz:

Note: Interference in sounds between signal 2 and signal 3 when make demodulation to them. All signals have been occurred distortion on them.

💻 Demodulation with a local carrier frequency that is different by 10 Hz:

Note: More Interference in sounds between signal 2 and signal 3 when make demodulation to them. All signals have been occurred more distortion on them.

Contributors



Ziad Sherif

Eslam Ashraf

🔒 License

Note: This software is licensed under MIT License, See License for more information ©SAMA3NY.