Discrete Impulse

R2026b

Generate discrete impulse

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Discrete Impulse block

To add a block to a model, double-click the canvas and start typing the block name. Then, select the block from the list.

Libraries:
DSP System Toolbox / Sources

Description

The Discrete Impulse block generates an impulse (the value 1) at output sample D+1, where you specify D using the Delay parameter (D ≥ 0). All output samples preceding and following sample D+1 are zero.

When D is a length-N vector, the block generates an M-by-N matrix output representing N distinct channels, where you specify frame size M using the Samples per frame parameter. The impulse for the ith channel appears at sample D(i)+1.

The Sample time parameter value, T_s, specifies the output signal sample period. The resulting frame period is MT_s.

Examples

Generate Discrete Impulse with Three Channels

This example shows how to generate a discrete impulse signal with three channels and a data type of double. The Discrete Impulse block has the following settings:

• Delay = [0 3 5]

• Sample time = 0.25

• Samples per frame = 4

• Output data type = double

Run the model and look at the output, dsp_examples_yout. The first few samples of each channel are shown below:

dsp_examples_yout(1:10,:)
ans =
     1     0     0
     0     0     0
     0     0     0
     0     1     0
     0     0     0
     0     0     1
     0     0     0
     0     0     0
     0     0     0
     0     0     0

The block generates an impulse at sample 1 of channel 1 (first column), at sample 4 of channel 2 (second column), and at sample 6 of channel 3 (third column).

Ports

Output

Port_1 — Discrete impulse signal

scalar | vector | matrix

Output signal containing a discrete impulse at output sample D(i)+1, where D is a scalar or vector specified by the Delay parameter. For more information, see Description.

Data Types: single | double | int8 | int16 | int32 | int64 | uint8 | uint16 | uint32 | uint64 | Boolean | fixed point

Parameters

Main

Delay (samples) — Number of zero-valued output samples

0 (default) | scalar | vector

The number of zero-valued output samples, D, preceding the impulse, specified as a scalar or vector of integer values, greater than or equal to zero. A length-N vector specifies an N-channel output.

Sample time — Output sample period

1 (default) | positive scalar

The sample period, T_s, of the output signal specified as a positive finite scalar. The output frame period is MT_s.

Samples per frame — Samples per frame

1 (default) | positive integer

The number of samples, M, in each output frame, specified as a positive integer scalar.

Data Types

Output data type — Output data type

double (default) | single | int8 | uint8 | int16 | uint16 | int32 | uint32 | int64 | uint64 | boolean | fixdt(1,16) | fixdt(1,16,0) | Inherit: Inherit via back propagation | <data type expression>

Specify the output data type for this block. You can select one of the following:

• A rule that inherits a data type, for example, Inherit: Inherit via back propagation. When you select this option, the output data type and scaling matches that of the next downstream block.

• A built-in data type, such as double

• An expression that evaluates to a valid data type, for example, fixdt(1,16)

For help setting data type parameters, display the Data Type Assistant by clicking the Show data type assistant button .

See Control Data Types of Signals (Simulink) for more information.

Data Type Assistant

Mode — Data type mode

Inherit (default) | Built in | Fixed point | Expression

Select how you would like to specify the data type properties of the Output data type. You can choose:

• Inherit — Lets you specify a rule for inheriting a data type, for example, Inherit: Same as input

• Built in— Lets you specify a built-in data type, for example, double

• Fixed point — Lets you specify the fixed-point attributes of the data type.

• Expression — Lets you specify an expression that evaluates to a valid data type, for example, fixdt(1,16)

For more information, see Specify Data Types Using Data Type Assistant (Simulink).

Signedness — Signedness of fixed-point data

Signed (default) | Unsigned

Specify whether the fixed-point data is signed or unsigned. Signed data can represent positive and negative values, but Unsigned data represents positive values only. For more information, see Specify Data Types Using Data Type Assistant (Simulink).

Scaling — Method for scaling fixed-point data

Best precision (default) | Binary point

Specify the method for scaling your fixed-point data to avoid overflow conditions and minimize quantization errors. For more information, see Specify Data Types Using Data Type Assistant (Simulink).

Dependencies

To enable this parameter, set Mode to Fixed point

Word length — Bit size of the word that holds the quantized integer

16 (default) | integer from 2 to 128

Specify the bit size of the word that holds the quantized integer as a positive integer from 2 to 128. For more information, see Specify Data Types Using Data Type Assistant (Simulink).

Dependencies

To enable this parameter, set Mode to Fixed point

Fraction length — Fraction length for fixed-point data type

0 (default) | integer scalar

Specify the fraction length of the fixed-point data type as a positive or negative integer scalar.

Dependencies

To enable this parameter, set Mode to Fixed point and Scaling to Binary point.

Data type override — Data type override mode

Inherit (default) | Off

Select the data type override mode for this signal. You can select:

• Inherit — Inherits the data type override setting specified for the model.

• Off — Ignores the data type override setting specified for the model and uses the fixed-point data type you specify.

Dependencies

To enable this parameter, set Mode to Built in or Fixed point. For more information, see Specify Data Types Using Data Type Assistant (Simulink).

Block Characteristics

Data Types	Boolean | double | fixed point | integer | single
Direct Feedthrough	no
Multidimensional Signals	no
Variable-Size Signals	no
Zero-Crossing Detection	no

Programmatic Use: Add Block

To add the block programmatically, use the add_block function with one of these library block paths as the source.

"dspsrcs4/Discrete  Impulse"

Example: add_block("dspsrcs4/Discrete Impulse","myModel/myBlock",MakeNameUnique="on")

Extended Capabilities

C/C++ Code Generation
Generate C and C++ code using Simulink® Coder™.

Fixed-Point Conversion
Design and simulate fixed-point systems using Fixed-Point Designer™.

Version History

Introduced before R2006a