TI DSK C6713 Simulink Model for Realtime Modulation and Demodulation

Download the Real time Modulation and Demodulation Models

You can download from the links below:

Real-time Modulation Model
Real-time Demodulation Model

THEORY

This is the last post of Amplitude and Demodulation using Texas Instrument DSK 6713 and I will try to windup all the important aspects of the term assignment. We have already discussed a simple simulink model of both Amplitude Modulation and Demodulation. You are recommended to see them first. Lets start with the basics.

We will make use of function generator and an oscilloscope. Both will be connected to the TI C6713 on line-in and line-out connectors. Frequency of Carrier Signal is fixed at 15 kHz while the message signal is varried from the function generator. Since DSK C6713 ensures realtime simulation, once the message signal is varied we will see on oscilloscope that modulated signal is also varying. Lets discuss different steps involved.

Block Diagram

C6713 Simulink Model - Amplitude Modulation

• Open a new simulink model and library browser

• Using Embedded Target For TIC6000 DSP menu select C6713 DSK Board Support.

• Using the Embedded Target For TIC6000 DSP tool in the library browser, select C6713 DSK Board Support and add ADC for Line In, DAC for Line Out and Reset Switch. You can extract all these from Simulink Library Browser.

• Implement the simulink model of AM as: You can also download from here.

• Message signal Line in parameters and carrier signal parameters can be set as following. This is very important. Set ADC Source as Line In, Sample Rate 19kHz, Word Length 16-bit. Amplitude :1.

Amplitude of the message signal can be change through function generator (up to 5KHz), whereas, frequency of the carrier signal is 15KHz.

• The output modulated signal observe in oscilloscope is:

C6713 Simulink Model - Amplitude De-Modulation

• Target the device in the similar manner as done above in amplitude modulation.

• A low pass filter has been designed in the FDA Tool in such a way that only the frequency of the message signal (5 KHz) is allow to pass through filter.

• Design the low pass filter using FDA Tool in Matlab.

• Export this filter to the simulink model

• Implement the simulink model of the demodulation. Click to enlarge please or download it from here.

• Run the model and observe the output at the oscilloscope.

CERTIFICATE

Muhammad Ahmed
Jamal Ahmed
Muhammad Faisal

For any queries feel free to contact

11:01 | Posted in Amplitude Demodulation, Amplitude Modulation, c6713, DSP, Electronics Projects, MATLAB, Matlab Simulink | Read More »

Amplitude Modulation on MATLAB Simulink

Download the Simulink Model:

Download here

What is Amplitude Modulation?

This topic is the result of Digital Signal Processing term project named Amplitude Modulation and Demodulation on Texas Instrument Kit DSK C6713 with Matlab Simulink. One of the fundamental part of our project is included in this very post. The whole term mini project will be gradually discussed in subsequent posts. Before we proceed, we must know what actually modulation and amplitude modulation is? A modulator alters the carrier waves corresponding to the variation of the modulating signals. Resulting modulated signal thus carries message information. Amplitude modulation is the process of changing the amplitude of a high frequency carrier signal corresponding to the amplitude of the modulating signal (Information). The wave whose amplitude is being varied is called the carrier wave and the signal doing the variation is called the modulating signal i-e message signal or information signal. The carrier is always almost a sinusoidal wave. The modulating or message signal can be a sine wave but it can be arbitrary waveform such as audio signal etc.

Some Mathematics :

For simplicity, suppose both carrier wave and modulating signal are sinusoidal:

vc = Vc sin wc t (c denotes carrier)

and

vm = Vm sin wm t (m denotes modulation)

We want the modulating signal to vary the carrier amplitude, Vc, so that:

vc = (Vc + Vm sin wmt).sin wc t

where (Vc + Vm sin wm t) is the new, varying carrier amplitude.

Expanding this equation gives:

vc = Vc sin ωc t + Vm sin ωc t. sin ωm t

which may be rewritten as:

vc = Vc [sin ωc t + m sin ωc t. sin ωm t]

where m = Vm/Vc and is called the modulation index.

sin ωc t.sin ωm t = (1/2) [cos(ωc - ωm) t - cos(ωc + ωm) t]

so, from the previous equation:

vc = Vc [sin ωc t + m sin ωc t. sin ωm t]

we can express vc as:

vc = Vc sin ωc t + (mVc/2) [cos(ωc - ωm) t] - (mVc/2) [cos(ωc + ωm) t]

The original carrier waveform, at frequency ωc, containing no variations and thus carrying no information.
A component at frequency (ωc - ωm) whose amplitude is proportional to the modulation index. This is called the Lower Side Frequency.
A component at frequency (ωc + ωm) whose amplitude is proportional to the modulation index. This is called the Upper Side Frequency.

AMPLITUDE MODULATION USING MATLAB SIMULINK

Lets discuss step by step the implementation of amplitude modulation on simulink modulation :-

Start the new Simulink model

Open the Simulink library browser

Create the simulation model of the AM

Message Signal:

A Sinusoidal signal of frequency 1 Hz, Amplitude=1
Carrier Signal of frequency 20 Hz and Amplitude=1

The above model is the equivalent of the mathematical expression:

s(t)=[1+m(t)](cos(2πfct))
Where;
m(t) represent the message signal
And cos(2πfct) represent the carrier

Run the Simulink model, the message, carrier and modulated output can be observed on the oscilloscope.

The above diagtam shows both supressed and without supressed carrier.You are recommended to see the following too :-

Amplitude Modulation on Matlab Simulink Model

CERTIFICATE OF OWNERSHIP

This project named “AMPLITUDE MODULATION USING MATLAB SIMULINK AND TEXAS INSTRUMENT KIT C6713”, in all respect is the property of the following personnel who undertake this project as the term project in EE-322 ‘DSP & Filters’ in summer semester 2010. However the copy of the project can be distributed upon the approval of the following members:-