Amplitude modulation Code in Matlab

Program

fs=500;

fc=50;

t=[0:2*fs]/fs;

x=2*sin(2*pi*t);

y=ammod(x,fc,fs);

z=fft(y);

f=[0:length(z)-1];

subplot(2,2,1);

plot(t,x);

xlabel('time');

xlabel('Freequency');
ylabel('amplitude');
title('Input Waveform');

subplot(2,2,2);

plot(f,y);

ylabel('amplitude');

title('modulated waveform');

subplot(2,2,3);

plot(f,z);

xlabel('Freequency');

ylabel('amplitude');

title('spectrum diagram');x= ammod(y,fc,fs);

subplot(2,2,4);

plot(t,x);

xlabel('time);

ylabel('amplitude);

title('demodulated waveform)

Output waveforms

SSB Modulator Internal Block Diagram

Internal Block diagram and Connections of SSB Modulator

Non Phase shifted Sinusoidal Input waveform - Message Signal

Non Phase shifted Sinusoidal Input waveform - Carrier Signal

Phase shifted Sinusoidal Input waveform - Message Signal

Phase shifted Sinusoidal Input waveform - Carrier Signal

Spectrum Analyser Block Properties

Spectrum Analyser Output




The Experiment

To perform this experiment first insert four sine wave blocks into the workspace

Then place two sine wave blocks together to a multiplier and the other two to another multiplier

In two of the sime wave blocks connected to the same multiplier change the inital phase reading to 90 degrees as shown in the source block parameters

Connect the outputs of the multipliers to an adder and the output of the adder to a spectrumm analyser

DSBSC using Internal Structure of blocks

DSBSC Internal Structure Block Diagram

Input Sine Wave 1 Parameters - Carrier Wave

Sine Wave Input Paraneters - Message Signal

Spectrum Analyser Output DSBSC

DSBSC

BLOCK DIAGRAM DSBSC MODULATOR

Source Block parameters

Modulator Properties DSBSC

DSBSC Modulated Wave

DSBSC Demodulator Blockset

DSBSC Demodulator Properties

DSBSC Demodulated Waveform

SSB MODULATION

MODULATOR BLOCKSET

SOURCE BLOCK PARAMETERS

MODULATOR PROPERTIES

MODULATED WAVE

DEMODULATION BLOCKSET

DEMODULATOR PROPERTIES WINDOW

DEMODULATED WAVEFORM

Freequency Modulation

FREQUENCY MODULATION

The Blocks required for frequency modulation are:
1.Sine wave Block

2. Frequency Modulation Block

3. Sampling Scope

Connect the blocks as shown in the diagram below

Block Diagram

The parameters for the Modulator along with freequency values and other necessary settings are shown in the diagram below

Modulator properties

The source parameters including frequency of the input sine wave are shown in the picture below

Source block parameters

The output waveform appears in the CRO as:

Modulated waveform

For demodulation connect a FM demodulator block in between the FM modulator block and the sampling scope and connect them as shown in the diagram below.

Demodulator block diagram

With the settings of the source and modulator blocks remaining the same adjust the demodulator to the necessary frequency and other parameters as necessary and as shown in the picture below:

FM Demodulator properties

The Demodulated output appears in the CRO as thus:

Demodulatoed Waveform

AM Modulation

The Block diagrams required for the AM Modulation are:

1. Sine Wave Block

2. Amplitude Modulator Block

3.Sampling Scope

Connect the blocks as shown in the diagram below

Block diagram of AM modulator in SIMULINK

The parameters of the input sine wave block are as given in the block below.

Set the parameters as shown in the diagram

Source block properties along with their values

The values of the modulator along with requisite frequencies are as given below

Modulator properties along with their values

The DSBSC modulated waveform is as given below

AM Modulated wave

                                                   Demodulated or Input wave

The lab maual can be downloaded from this link along with all thie pics above

https://docs.google.com/file/d/0B_sevGyWoSsNdEsxOE9SbzctUWc/edit?usp=sharing