SimulinkHow-ToBeginner · 3 min read

How to Add AWGN Channel in Simulink: Step-by-Step Guide

In Simulink, add the AWGN Channel block from the Communications Toolbox library to your model. Configure its parameters like Signal-to-Noise Ratio (SNR) to simulate additive white Gaussian noise on your signal.

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Syntax

The AWGN Channel block is used to add white Gaussian noise to a signal in Simulink. You can find it under Simulink Library Browser > Communications Toolbox > Channels.

Key parameters include:

SNR (dB): Sets the signal-to-noise ratio in decibels.
Signal power: Defines the power of the input signal (can be set to 'Measured' or a fixed value).
Mode: Choose between 'Signal to noise ratio (SNR)' or 'Noise power'.

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AWGN Channel block parameters:
- SNR (dB): numeric value (e.g., 20)
- Signal power: 'Measured' or numeric
- Mode: 'Signal to noise ratio (SNR)' or 'Noise power'

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Example

This example shows how to add an AWGN Channel block to a simple Simulink model that passes a sine wave through the noise channel.

The model includes:

A Sine Wave block generating a clean signal.
An AWGN Channel block adding noise with 10 dB SNR.
A Scope block to visualize the noisy signal.

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1. Open Simulink and create a new model.
2. Add a <code>Sine Wave</code> block from <code>Sources</code>.
3. Add an <code>AWGN Channel</code> block from <code>Communications Toolbox &gt; Channels</code>.
4. Connect the output of the Sine Wave to the input of the AWGN Channel.
5. Add a <code>Scope</code> block from <code>Sinks</code> and connect it to the AWGN Channel output.
6. Double-click the AWGN Channel block and set <code>SNR (dB)</code> to 10.
7. Run the simulation and open the Scope to see the noisy sine wave.

Output

Scope window shows a sine wave with noise added, appearing less smooth than the original clean sine wave.

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Common Pitfalls

Common mistakes when using the AWGN Channel block include:

Not setting the SNR correctly, leading to either too much or too little noise.
Forgetting to set the signal power mode properly; if the input signal power is unknown, set it to 'Measured' to auto-calculate.
Connecting incompatible signal types; the AWGN Channel expects real or complex signals.

Example of a wrong setting:

Setting SNR to 0 dB unintentionally adds very high noise, making the signal unusable.

Correct approach:

Set SNR to a realistic value like 10 or 20 dB depending on your noise tolerance.

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Wrong:
AWGN Channel block parameters:
- SNR (dB): 0
- Signal power: fixed 1

Right:
AWGN Channel block parameters:
- SNR (dB): 15
- Signal power: 'Measured'

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Quick Reference

Parameter	Description	Typical Values
SNR (dB)	Signal-to-noise ratio in decibels	10 to 30
Signal power	Power of input signal	'Measured' or numeric
Mode	Defines noise calculation method	'Signal to noise ratio (SNR)' or 'Noise power'

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Key Takeaways

Add the AWGN Channel block from Communications Toolbox to simulate noise in Simulink.

Set the SNR parameter to control noise level realistically.

Use 'Measured' signal power if input power is unknown for accurate noise addition.

Connect compatible signal types to avoid simulation errors.

Visualize noisy signals with Scope to verify noise effects.