## AM Generation using Simulink

Contents

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 (S
_{c}) = A_{c}sin(2πf_{c}t) - Message signal (S
_{m}) = A_{m}sin(2πf_{m}t) # fm must be smaller than fc

When carrier amplitude is altered with respect to message signal,

- Modulated Signal = (A
_{c}+ A_{m}sin(2 πf_{m}t))*sin(2 πf_{c}t)

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

**Modulated signal= (1+ msin(2 πf**_{m}t))*A_{c}sin(2 πfct)

Where,

- A
_{c }= Carrier signal amplitude - A
_{m }= Message signal amplitude - f
_{c}= Carrier frequency - fm =Message frequency

# Generating AM in Simulink

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

## Blocks Required

Analyzing the equation we need,

- Carrier Signal Source
- Message Signal Source
- Blocks for viewing the signals – Scope
- Product Block
- Summer Block
- 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