DSP System Toolbox blocks in Simulink - Step-by-Step Execution

Concept Flow - DSP System Toolbox blocks

Input Signal

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DSP Block Selection

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Block Processing

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Output Signal

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Visualization or Further Processing

The flow shows how an input signal passes through a selected DSP System Toolbox block for processing, then outputs the processed signal for visualization or further use.

Execution Sample

Simulink

% Simulink model snippet
% Input signal -> FIR Filter block -> Output
inputSignal = sin(2*pi*0.1*(0:99));
filteredSignal = dsp.FIRFilter('Numerator',ones(1,5)/5).step(inputSignal);

This code applies a simple FIR filter block from DSP System Toolbox to smooth an input sine wave signal.

Execution Table

Step	Action	Input Signal Sample	Block Used	Output Signal Sample
1	Input signal generated	sin(0)=0	None	N/A
2	Input signal generated	sin(0.2*pi)=0.5878	None	N/A
3	FIR Filter block initialized	N/A	FIR Filter (5 taps)	N/A
4	Filter applied to first 5 samples	[0, 0.5878, 0.9511, 0.9511, 0.5878]	FIR Filter	0.6156 (average)
5	Filter applied to next samples	[0.5878, 0.9511, 0.9511, 0.5878, 0]	FIR Filter	0.6156 (average)
6	Filter applied to last samples	[0.9511, 0.9511, 0.5878, 0, 0]	FIR Filter	0.4980 (average)
7	Output signal ready	N/A	FIR Filter	Filtered signal array
8	End of processing	N/A	N/A	N/A

💡 All input samples processed through FIR Filter block, output signal produced.

Variable Tracker

Variable	Start	After Step 4	After Step 5	After Step 6	Final
inputSignal	empty	[0, 0.5878, 0.9511, 0.9511, 0.5878]	[0.5878, 0.9511, 0.9511, 0.5878, 0]	[0.9511, 0.9511, 0.5878, 0, 0]	full sine wave array
filteredSignal	empty	0.6156	0.6156	0.4980	full filtered array

Key Moments - 2 Insights

Why does the output signal start producing values only after the first few input samples?

Because the FIR filter uses a window of 5 samples, it needs enough input data to compute the first output value, as shown in execution_table steps 4-6.

What happens if the input signal length is shorter than the filter length?

The filter cannot fully apply because it requires enough samples equal to its tap length; output will be incomplete or zero until enough samples arrive.

Visual Quiz - 3 Questions

Look at the execution table, what is the output signal sample at step 4?

A 0.6156

B 0.5878

C 0.9511

D 0.4980

💡 Hint

Check the 'Output Signal Sample' column at step 4 in the execution_table.

At which step does the FIR Filter block get initialized?

A Step 1

B Step 5

C Step 3

D Step 7

💡 Hint

Look at the 'Action' column for block initialization in the execution_table.

If the filter length changed from 5 to 3 taps, how would the output at step 4 change?

A Output would remain the same

B Output would be average of 3 samples instead of 5

C Output would be zero

D Filter would not work

💡 Hint

Consider how FIR filter output depends on the number of taps as shown in variable_tracker.

Concept Snapshot

DSP System Toolbox blocks process signals step-by-step.
Input signal flows into a block (e.g., FIR Filter).
Block applies its algorithm using internal parameters.
Output signal is produced after processing.
Filter length affects how soon output appears.
Blocks can be chained for complex processing.

Full Transcript

This visual execution shows how DSP System Toolbox blocks in Simulink process signals. The input signal is generated as a sine wave. The FIR Filter block is initialized with 5 taps. The filter processes the input signal in windows of 5 samples, producing output values starting after enough samples are available. Variables track input and output signal values step-by-step. Key moments clarify why output starts after initial samples and what happens if input is too short. The quiz tests understanding of output values, block initialization, and effect of filter length changes.