Amplitude modulation (AM) is a one of the conventional technique used to transmit message signals using a carrier wave. The amplitude or strength of the high frequency carrier wave is modified in accordance with amplitude of the message signal. If you are a newbie to Simulink, please read our article Introduction to Simulink.

First of all lets get into the basics..

• Carrier signal (Sc) = Acsin(2πfct)
• Message signal (Sm) = Amsin(2πfmt)   # fm must be smaller than fc

When carrier amplitude is altered with respect to message signal,

• Modulated Signal = (Ac+ Amsin(2 πfmt))*sin(2 πfct)

In terms of modulation index (m=Am/Ac) the equation becomes

• Modulated signal= (1+ msin(2 πfmt))*Acsin(2 πfct)

Where,

• A= Carrier signal amplitude
• A= Message signal amplitude
• fc= Carrier frequency
• fm =Message frequency

For generating AM we just have to implement the equation of AM in block level.

## Blocks Required

Analyzing the equation we need,

1. Carrier Signal Source
2. Message Signal Source
3. Blocks for viewing the signals – Scope
4. Product Block
5. Summer Block
6. Constant Block

We can find these blocks in the following locations of Simulink Library…

### Carrier, Message, Constant blocks

• Simulink –> Sources –> Sine wave
• Simulink –> Sources –> Constant

### View Block

• Simulink –> Sink –> Scope

### Product and Summer Block

• Simulink –> Math Operations–> Product
• Simulink –> Math Operations–> Summer

## Block Diagram

Block parameters can be changed by selecting the block and parameter that I used are given below..

• Carrier Signal frequency = 2*pi*25 and sampling time=1/5000
• Message Signal frequency = 2*pi and sampling time=1/5000
• Amplitudes of both signals are 1

## Output Waveforms

• Ligo George says:

Sorry, I don’t understand. Can you please elaborate ?

• amani says:

sorry i have to do a AM is simulink matlab , and i don’t get the good resolution?? i have to do it by un source signal at NRZ code withe a sin signale ??? can eny one help me plz !!

• Ligo George says:

Sorry we don’t have VHDL.

• Ankit Kumar says:

hi can you tell me how to convert it into vhdl code