DSP System Toolbox blocks in Simulink - Mini Project: Build & Apply

DSP System Toolbox Blocks in Simulink

📖 Scenario: You are working on a simple audio processing system using Simulink. You want to use DSP System Toolbox blocks to create a system that filters an audio signal and then measures its power.

🎯 Goal: Build a Simulink model using DSP System Toolbox blocks to filter an input signal with a lowpass filter and then measure the power of the filtered signal.

📋 What You'll Learn

Create a Simulink model named audio_filter_power

Add a DSP System Toolbox Lowpass Filter block with cutoff frequency 1000 Hz

Add a DSP System Toolbox Power Measurement block

Connect the blocks correctly to process the input signal

Display the output power measurement

💡 Why This Matters

🌍 Real World

DSP System Toolbox blocks in Simulink are used to design and simulate digital signal processing systems such as audio filters, communication systems, and sensor data processing.

💼 Career

Understanding how to use DSP System Toolbox blocks is important for engineers working in signal processing, embedded systems, and communications to prototype and test algorithms efficiently.

1

Create the Simulink model and add input signal

Create a new Simulink model named audio_filter_power. Add a Sine Wave block from the Simulink Sources library. Set the frequency to 500 Hz and the sample time to 1/8000. Connect the output of the Sine Wave block to a Scope block to visualize the signal.

Simulink

% Create a new model and add a Sine Wave block with frequency 500 Hz and sample time 1/8000
% Connect it to a Scope block
% Your code here

Hint

Use new_system to create the model. Use add_block to add blocks. Set the frequency and sample time properties for the Sine Wave block. Connect blocks with add_line.

2

Add DSP System Toolbox Lowpass Filter block

Add a DSP System Toolbox Lowpass Filter block to the model. Set its cutoff frequency to 1000 Hz. Connect the output of the Sine Wave block to the input of the Lowpass Filter block.

Simulink

% Add DSP System Toolbox Lowpass Filter block with cutoff frequency 1000 Hz
% Connect Sine Wave output to Lowpass Filter input
% Your code here

Hint

Use the DSP System Toolbox library path dspmlti4/Filters/Lowpass Filter to add the Lowpass Filter block. Use set_param to set the cutoff frequency.

3

Add DSP System Toolbox Power Measurement block and connect

Add a DSP System Toolbox Power Measurement block to the model. Connect the output of the Lowpass Filter block to the input of the Power Measurement block. Then connect the output of the Power Measurement block to the Scope block.

Simulink

% Add DSP System Toolbox Power Measurement block
% Connect Lowpass Filter output to Power Measurement input
% Connect Power Measurement output to Scope input
% Your code here

Hint

Use the DSP System Toolbox path dspmlti4/Measurements/Power Measurement to add the Power Measurement block. Connect the blocks in the correct order.

4

Run the simulation and display the output

Run the simulation for 0.01 seconds. Open the Scope block to view the power measurement output of the filtered signal.

Simulink

% Run the simulation for 0.01 seconds
% Open the Scope block to view output
% Your code here

Hint

Use set_param to set the stop time. Use sim to run the simulation. Use open_system to open the Scope window.

Practice

1. Which of the following is a primary use of DSP System Toolbox blocks in Simulink?

easy

A. To manage database connections

B. To write low-level hardware drivers

C. To create 3D animations

D. To build and simulate signal processing systems visually

Solution

1. Step 1: Understand the purpose of DSP System Toolbox blocks

   These blocks are designed to help build and simulate signal processing systems visually in Simulink.

2. Step 2: Eliminate unrelated options

   The remaining options relate to hardware drivers, animations, and databases, which are not functions of DSP System Toolbox blocks.

3. Final Answer:

   To build and simulate signal processing systems visually -> Option D

4. Quick Check:

   DSP System Toolbox = Visual signal processing [OK]

Hint: Remember DSP blocks are for signal processing, not hardware or graphics [OK]

Common Mistakes:

• Confusing DSP blocks with hardware programming
• Thinking DSP blocks create animations
• Assuming DSP blocks manage databases

2. Which block from the DSP System Toolbox is used to perform a Fast Fourier Transform (FFT) in Simulink?

easy

A. FFT block

B. Gain block

C. Scope block

D. Filter block

Solution

1. Step 1: Identify the block for frequency analysis

   The FFT block is specifically designed to compute the Fast Fourier Transform of signals.

2. Step 2: Confirm other blocks' functions

   Filter blocks modify signals, Scope blocks display signals, and Gain blocks multiply signals by a constant.

3. Final Answer:

   FFT block -> Option A

4. Quick Check:

   FFT block = Fast Fourier Transform [OK]

Hint: FFT block always computes frequency transform [OK]

Common Mistakes:

• Choosing Filter block for FFT
• Confusing Scope block with processing block
• Selecting Gain block for transform

3. Given a Simulink model using a DSP System Toolbox FIR Filter block with coefficients [1 2 1], what is the output for input signal [1 0 0 0]?

medium

A. [1 0 0 0]

B. [1 2 1 0]

C. [0 1 2 1]

D. [1 3 3 1]

Solution

1. Step 1: Understand FIR filter output calculation

   The output is the convolution of input signal with filter coefficients [1 2 1].

2. Step 2: Compute convolution of [1 0 0 0] and [1 2 1]

   Convolution result is [1*1, 1*2+0, 1*1+0, 0] = [1, 2, 1, 0].

3. Final Answer:

   [1 2 1 0] -> Option B

4. Quick Check:

   Input convolved with coefficients = output [OK]

Hint: FIR output = input convolved with coefficients [OK]

Common Mistakes:

• Ignoring convolution and taking input as output
• Reversing coefficient order incorrectly
• Adding coefficients instead of convolving

4. You have a Simulink model using a DSP System Toolbox block that throws an error: "Input signal dimension mismatch." What is the most likely cause?

medium

A. The input signal size does not match the block's expected input dimension

B. The block is missing from the library

C. The output signal is connected incorrectly

D. The Simulink version is outdated

Solution

1. Step 1: Analyze the error message

   The error "Input signal dimension mismatch" indicates the input size is not what the block expects.

2. Step 2: Check common causes

   Missing blocks or output connection errors cause different errors; version issues rarely cause dimension mismatch.

3. Final Answer:

   The input signal size does not match the block's expected input dimension -> Option A

4. Quick Check:

   Dimension mismatch = input size error [OK]

Hint: Dimension mismatch means input size is wrong [OK]

Common Mistakes:

• Assuming missing block causes dimension error
• Blaming output connection for input dimension error
• Ignoring input size requirements

5. You want to design a Simulink model using DSP System Toolbox blocks to filter noise from a signal sampled at 1 kHz. Which combination of blocks is best suited for this task?

hard

A. FFT block and Constant block

B. Gain block and Scope block

C. FIR Filter block with lowpass coefficients and Spectrum Analyzer block

D. Mux block and Demux block

Solution

1. Step 1: Identify blocks for noise filtering

   The FIR Filter block can remove unwanted frequencies using lowpass coefficients.

2. Step 2: Identify blocks for signal analysis

   The Spectrum Analyzer block helps visualize the frequency content to verify filtering.

3. Step 3: Evaluate other options

   Gain and Scope do not filter noise; FFT and Constant do not filter; Mux/Demux combine signals but do not filter.

4. Final Answer:

   FIR Filter block with lowpass coefficients and Spectrum Analyzer block -> Option C

5. Quick Check:

   Filter + Analyzer = noise removal and check [OK]

Hint: Use filter block to remove noise, analyzer to check [OK]

Common Mistakes:

• Choosing Gain or Scope for filtering
• Using FFT without filtering
• Confusing signal combining blocks with filtering