DSP Blockset

Discrete Impulse

Generate a discrete impulse.

Library

DSP Sources

Description

The Discrete Impulse block generates an impulse (the value 1) at output sample D+1, where D is specified by 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 frame size M is specified by the Samples per frame parameter. The impulse for the ith channel appears at sample D(i)+1. For M=1, the output is sample-based; otherwise, the output is frame-based.

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

The Data type parameter allows you to specify an output precision of double, single, or Boolean. Note, however, that most of the blocks in the DSP Blockset accept only double precision inputs. Use the Simulink Data Type Conversion block to convert integer data types to double precision. See "Working with Data Types" in the Simulink documentation for a complete discussion of data types, as well as a list of Simulink blocks capable of reduced-precision operations.

Example

Construct the model below.

Configure the Discrete Impulse block to generate a frame-based three-channel output of type double, with impulses at samples 1, 4, and 6 of channels 1, 2, and 3, respectively. Use a sample period of 0.25 and a frame size of 4. The corresponding settings should be as follows:

• Delay = [0 3 5]
• Sample time = 0.25
• Samples per frame = 4
• Data type = Double

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

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).

Dialog Box

Delay

The number of zero-valued output samples, D, preceding the impulse. A length-N vector specifies an N-channel output.

Sample time

The sample period, T_s, of the output signal. The output frame period is M*T_s.

Samples per frame

The number of samples, M, in each output frame.

Data type

The precision of the output.

See Also

Data Type Conversion	Simulink
DSP Constant	DSP Blockset
Multiphase Clock	DSP Blockset
N-Sample Enable	DSP Blockset
Signal From Workspace	DSP Blockset
impz	Signal Processing Toolbox

See Creating Signals Using Signal Generator Blocks for related information.

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