Repeat
Resample input at higher rate by repeating values
- Library:
DSP System Toolbox / Signal Operations
DSP System Toolbox HDL Support / Signal Operations
Description
The Repeat block upsamples each channel of the Mi-by-N input to a rate L times higher than the input sample rate. To do so, the block repeats each consecutive input sample L times at the output. You specify the integer L in the Repetition count parameter.
You can use the Repeat block in triggered subsystems when you set the
Rate options parameter to Enforce single-rate
processing
.
Ports
Input
Port_1
— Input signal
scalar | vector | matrix
Specify the input signal as a real or a complex-valued scalar, vector, or a matrix.
When you set Input processing to
Columns as channels (frame based)
and
Rate options to Enforce
single-rate processing
, the input can be a
variable-size signal. That is, the frame size (number of rows) and the
number of channels (columns) of the signal can change during
simulation.
Data Types: single
| double
| int8
| int16
| int32
| uint8
| uint16
| uint32
| Boolean
| fixed point
Complex Number Support: Yes
Output
Port_1
— Output signal
scalar | vector | matrix
The Repeat block outputs a signal that has the same data type and complexity as the input signal. The size of the output depends on the Repetition count and Rate options parameters.
If you set Repetition count to L and Rate options to:
Enforce single-rate processing
–– The block maintains the input sample rate by increasing the output frame size by a factor of L.Allow multirate processing
–– The block resamples the signal such that the output sample rate is L times faster than the input sample rate. The output signal has the same frame size as the input signal.
When the input is a variable-size signal, the output is also a variable-size signal.
Data Types: single
| double
| int8
| int16
| int32
| uint8
| uint16
| uint32
| Boolean
| fixed point
Complex Number Support: Yes
Parameters
Repetition count
— Repetition count
5
(default) | positive integer
Specify the repetition count L as a positive integer. This value is the number of times that the block repeats the input value at the output. This is the factor by which the block increases the output frame size or sample rate.
Input processing
— Method to process input signals
Columns as channels (frame
based)
(default) | Elements as channels (sample based)
Specify how the block should process the input by setting this parameter to one of these options:
Columns as channels (frame based)
— When you select this option, the block treats each column of the input as a separate channel. In this mode, the block can perform single-rate or multirate processing.Elements as channels (sample based)
— When you select this option, the block treats each element of the input as a separate channel. In this mode, the block always performs multirate processing.
Rate options
— Method by which block upsamples input
Enforce single-rate
processing
(default) | Allow multirate processing
Specify the method by which the block upsamples the input by selecting one of these options:
Enforce single-rate processing
— When you select this option, the block maintains the input sample rate by increasing the output frame size by a factor of L. To select this option, you must set the Input processing parameter toColumns as channels (frame based)
.Allow multirate processing
— When you select this option, the block resamples the signal such that the output sample rate is L times faster than the input sample rate.
Initial conditions
— Initial conditions
0
(default) | scalar | matrix
Specify the value with which the block is initialized for cases of nonzero latency as a scalar or a matrix.
Dependencies
To enable this parameter, set Rate options to Allow
multirate processing
.
Model Examples
Block Characteristics
Data Types |
|
Direct Feedthrough |
|
Multidimensional Signals |
|
Variable-Size Signals |
|
Zero-Crossing Detection |
|
More About
Frame-Based Processing
When you set the Input processing parameter to Columns as
channels (frame based)
, the block upsamples each column of the
input over time. In this mode, the block can perform either single-rate or multirate
processing. You can use the Rate options parameter to specify
how the block upsamples the input.
When you set the Rate options parameter to
Enforce single-rate processing
, the input and output of the block have the same sample rate. In this mode, the block outputs a signal with a proportionally larger frame size than the input. The block upsamples each channel independently by repeating each row of the input matrix L times at the output. For upsampling by a factor of L, the output frame size is L times larger than the input frame size (Mo = Mi*L), but the input and output frame rates are equal.For an example that shows how the Repeat block operates in the single-rate processing mode, see Repeat Signal In Single-Rate Processing Mode.
When you set the Rate options parameter to
Allow multirate processing
, the block treats an Mi-by-N matrix input as N independent channels. The block generates the output at the faster (upsampled) rate by using a proportionally shorter frame period at the output port than at the input port. For L repetitions of the input, the output frame period is L times shorter than the input frame period (Tfo = Tfi/L). In this mode, the output always has the same frame size as the input.For an example that shows how the Repeat block operates in the multirate frame-based processing mode, see Repeat Signal In Multirate Frame-Based Processing Mode.
Sample-Based Processing
When you set the Input processing parameter to
Elements as channels (sample based)
, the block treats
an M-by-N matrix input as
M*N independent channels, and upsamples
each channel over time. The block upsamples each channel over time such that the
output sample rate is L times higher than the input sample rate
(Tso =
Tsi/L).
In this mode, the output is always the same size as the input.
Nonzero Latency
The Repeat block has tasking latency for a multirate multitasking operation:
In the multirate sample-based processing mode, the block repeats the initial condition for each channel for the first L output samples. The first element of the input channel appears as output sample L+1. The Initial conditions parameter can be an Mi-by-N matrix containing one value for each channel, or a scalar value that the block applies to all signal channels.
In the multirate frame-based processing mode, the block repeats the first row of the initial condition matrix for the first L output samples, the second row of the initial condition matrix for the next L output samples, and so on. The first row of the first input matrix appears in the output as sample MiL+1. The Initial conditions parameter can be an Mi-by-N matrix, or a scalar value that the block repeats across all elements of the Mi-by-N matrix.
Note
For more information on latency and Simulink® tasking modes, see Excess Algorithmic Delay (Tasking Latency) and Time-Based Scheduling and Code Generation (Simulink Coder).
Zero Latency
The Repeat block has zero-tasking latency for
all single-rate operations. The block is in a single-rate mode if you set the
Repetition count parameter to 1
or if
you set the Input processing parameter to Columns
as channels (frame based)
and the Rate
options parameter to Enforce single-rate
processing
.
The Repeat block also has zero-tasking latency for multirate operations if you run your model in Simulink single-tasking mode.
Zero-tasking latency means that the block repeats the first input (received at
t=0
) for the first L
output samples, the second input for the next L output samples,
and so on.
Extended Capabilities
C/C++ Code Generation
Generate C and C++ code using Simulink® Coder™.
Generated code relies on the memcpy
or
memset
function (string.h
) under certain
conditions.
HDL Code Generation
Generate Verilog and VHDL code for FPGA and ASIC designs using HDL Coder™.
HDL Coder™ provides additional configuration options that affect HDL implementation and synthesized logic.
The Repeat block uses fewer hardware resources than the Upsample block. If your algorithm does not require zero-padding upsampling, use the Repeat block.
This block has one default HDL architecture.
ConstrainedOutputPipeline | Number of registers to place at
the outputs by moving existing delays within your design. Distributed
pipelining does not redistribute these registers. The default is
|
InputPipeline | Number of input pipeline stages
to insert in the generated code. Distributed pipelining and constrained
output pipelining can move these registers. The default is
|
OutputPipeline | Number of output pipeline stages
to insert in the generated code. Distributed pipelining and constrained
output pipelining can move these registers. The default is
|
Input processing set to Columns as channels
(frame based)
is not supported.
Fixed-Point Conversion
Design and simulate fixed-point systems using Fixed-Point Designer™.
Version History
Introduced before R2006aR2022b: Support for variable-size input signal
Starting in R2022b, when you set Input processing to
Columns as channels (frame based)
and Rate
options to Enforce single-rate processing
,
the input can be a variable-size signal. That is, the frame size (number of rows)
and the number of channels (columns) of the signal can change during
simulation.
When the input is a variable-size signal, the output is also a variable-size signal.
See Also
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