FIR Rate Conversion

Perform polyphase FIR sample rate conversion

Libraries:
DSP System Toolbox / Filtering / Multirate Filters

Description

The FIR Rate Conversion block performs an efficient polyphase sample rate conversion using a rational factor L/M along the first dimension. The block treats each column of the input as a separate channel and resamples the data in each channel independently over time.

Conceptually, the rate converter combines an FIR interpolator followed by an FIR decimator. The following schematic contains an upsampler, a combined anti-imaging and anti-aliasing FIR filter, and a downsampler. To design an FIR filter which acts as a combined anti-imaging and anti-aliasing FIR filter, use the designMultirateFIR function.

The rate converter does the following:

Upsamples the input to a higher rate by inserting L−1 zeros between input samples.
Passes the upsampled data through an FIR filter.
Downsamples the filtered data to a lower rate by discarding M-1 consecutive samples following each sample that the block retains.

FIR rate converter contains an upsampler followed by an anti-imaging, anti-aliasing FIR filter, followed by a downsampler.

Note that the actual block algorithm implements a polyphase structure, an efficient equivalent of the combined system depicted in the diagram. For more details, see Algorithms.

Examples

GSM Digital Down Converter in Simulink

Simulate steady-state behavior of a fixed-point digital down converter for GSM (Global System for Mobile) baseband conversions. The example model uses blocks from Simulink® and the DSP System Toolbox™ to emulate the operation of the TI GC4016 Quad Digital Down Converter (DDC).

Open Model

Convert Sample Rate of Speech Signal

Convert sample rate of speech signal.

Open Model

Ports

Input

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Port_1(In1) — Input signal
vector | matrix

Specify the input signal as a vector or a matrix of size P-by-Q. The input columns represent the Q independent channels.

The block supports variable-size input signals (frame length changes during simulation) when you set Rate options to Enforce single-rate processing. When the block accepts variable-size input signals, they can be of arbitrary frame length, that is, the input frame length does not have to be a multiple of the decimation factor. For fixed-size signals, the frame length can be arbitrary under certain conditions. For more details, see Frame-Based Processing.

When the block input is fixed point, all internal data types are signed fixed point.

Output

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Port_1(Out1) — Rate converted signal
vector | matrix

Rate converted signal, returned as a vector or a matrix.

When you set the Rate options parameter to:

Enforce single-rate processing –– The block maintains the input sample rate and resamples the signal by changing the output frame size by a factor of L/M.
The output has an upper bound size of ceil(LP/M)-by-Q for an input of size P-by-Q.
Allow multirate processing –– The block decimates the signal such that the output signal sample rate is L/M times the input sample rate.
The output frame size is the same as the input frame size, F_o = (L/M)×F_i
All blocks connected to the output operate at F_o, and all blocks connected to the input operate at F_i.
For more details, see Frame-Based Processing.

Parameters

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Coefficient source — Mode of operation
Auto (default) | Dialog parameters | Filter object

The FIR Rate Conversion block can operate in three different modes. Select the mode in the Coefficient source group box.

Dialog parameters — Enter information about the filter, such as FIR filter coefficients in the block dialog box.
Filter object — Specify the filter using a dsp.FIRRateConverter System object™.
Auto (default) — The block determines the filter coefficients.

The settings in the FIR Rate Conversion block dialog box change based on the mode selected.

Main Tab

Interpolation factor — Interpolation factor
`3` (default) | positive integer

Specify the interpolation factor, L, as a positive integer. The block upsamples the signal by this value before filtering it.

Dependencies

To enable this parameter, set Coefficient source to either Dialog parameters or Auto.

FIR filter coefficients — FIR filter coefficients
`designMultirateFIR(3,2)` (default) | vector

Specify the FIR filter coefficients in descending powers of z. By default, the block uses the designMultirateFIR(3,2) function to compute the filter coefficients.

Dependencies

To enable this parameter, set Coefficient source to Dialog parameters.

Decimation factor — Decimation factor
`2` (default) | positive integer

Specify the decimation factor, M, as a positive integer. The block downsamples the signal by this value after filtering it.

Dependencies

To enable this parameter, set Coefficient source to either Dialog parameters or Auto.

Rate options — Enforce single-rate or allow multirate processing
`Enforce single-rate processing` (default) | `Allow multirate processing`

Specify whether to enforce single-rate processing or allow multirate processing.

Enforce single-rate processing –– The output frame size P_o is L/M times the input frame size P_i, where L is the interpolation factor and M is the decimation factor.
P_o = (L/M)×P_i
The output signal rate in Simulink^® equals the input signal rate.
F_o = F_i
Allow multirate processing –– The output frame size equals the input frame size.
P_o = P_i
The output signal rate in Simulink is L/M times the input signal rate.
F_o = (L/M)×F_i
All blocks connected to the output operate at F_o, and all blocks connected to the input operate at F_i.

Filter object — Filter object
`FRC` (default) | `dsp.FIRRateConverter` System object

Specify the multirate filter object that you want the block to implement. The specified filter object must be a dsp.FIRRateConverter System object.

You can define the System object in the block mask or in a MATLAB^® workspace variable.

For information on creating System objects, see Define Basic System Objects.

Dependencies

This parameter appears when Coefficient source is set to Filter object.

Allow arbitrary frame length for fixed-size input signals — Allow arbitrary frame length for fixed-size input signals
off (default) | on

Specify whether fixed-size input signals (whose size does not change during simulation) can have an arbitrary frame length, where the frame length does not have to be a multiple of the decimation factor. The block uses this parameter setting only for fixed-size input signals and ignores this parameter if the input has a variable-size.

When the input signal is a variable-size signal, the signal can have arbitrary frame length, that is, the frame length does not have to be a multiple of the decimation factor.

For fixed-size input signals, if you:

Select the Allow arbitrary frame length for fixed-size input signals parameter, the frame length of the signal does not have to be a multiple of the decimation factor. If the input is not a multiple of the decimation factor, then the output is generally a variable-size signal. Therefore, to support arbitrary input size, the block must also support variable-size operations, which you can enable by selecting the Allow arbitrary frame length for fixed-size input signals parameter.
Clear the Allow arbitrary frame length for fixed-size input signals parameter, the input frame length must be a multiple of the decimation factor.

Dependency

To enable this parameter, set Rate options to Enforce single-rate processing.

View Filter Response — Visualize filter response
button

Select this parameter to open the Filter Visualization Tool, fvtool, and display the magnitude response of the FIR filter. The response is based on the parameters selected in the block dialog box. Changes made to these parameters update fvtool.

To update the magnitude response while fvtool is running, modify the block parameters and click Apply.

To view the magnitude response and phase response simultaneously, click the Magnitude and Phase responses button on the toolbar.

Data Types Tab

When Coefficient source is set to Filter object, the fixed-point settings of the filter object specified on the Main tab are displayed on the Data Types tab. You cannot change these settings directly on the block dialog box. To change the fixed-point settings, you must edit the filter object.

For more information on System objects, see the What Are System Objects?.

When Coefficient source is set to Auto, the block chooses the filter coefficients automatically. For more information on the filter design algorithm that the block uses, see Specify FIR Filter Coefficients.

Rounding mode — Rounding method
`Floor` (default) | `Ceiling` | `Convergent` | `Nearest` | `Round` | `Simplest` | `Zero`

Specify the rounding mode for fixed-point operations as:

Floor
Ceiling
Convergent
Nearest
Round
Simplest
Zero

For more details, see Rounding Modes.

The filter coefficients do not obey this parameter and always round to Nearest.

Note

The Rounding mode and Saturate on integer overflow parameters have no effect on numerical results when all these conditions are met:

Product output data type is Inherit: Inherit via internal rule.
Accumulator data type is Inherit: Inherit via internal rule.
Output data type is Inherit: Same as accumulator.

With these data-type settings, the block operates in a full-precision mode.

Dependencies

To enable this parameter, set Coefficient source to either Dialog parameters or Auto.

Saturate on integer overflow — Overflow handling method
off (default) | on

Select this parameter to saturate the result of the fixed-point operation. Clear this parameter to wrap the result of the fixed-point operation. For details on saturate and wrap, see Overflow Handling for fixed-point operations.

Note

The Rounding mode and Saturate on integer overflow parameters have no effect on numeric results when all these conditions are met:

Product output data type is Inherit: Inherit via internal rule.
Accumulator data type is Inherit: Inherit via internal rule.

With these data-type settings, the block operates in a full-precision mode.

Dependencies

This parameter is editable only when Coefficient source is set to either Dialog parameters or Auto.

Coefficients — Coefficients data type
`Inherit: Same word length as input` (default) | `fixdt(1,16)` | `fixdt(1,16,0)`

Coefficients specifies the data type of the filter coefficients.

Inherit: Same word length as input –– The block inherits the word length of the coefficients from the fixed-point input. The fraction length is determined based on the coefficient values in order to obtain the best possible precision.
fixdt(1,16) –– The coefficients data type is a signed, binary-point, scaled, fixed-point data type with a word length of 16 bits.
fixdt(1,16,0) –– The coefficients data type is a signed, binary-point, scaled, fixed-point data type with a word length of 16 bits and a fraction length of 0.

Alternatively, you can set the Coefficients data type by using the Data Type Assistant. To use the assistant, click the Show data type assistant button .

For more information on the data type assistant, see Specify Data Types Using Data Type Assistant (Simulink).

For a diagrammatic representation of how this block uses the filter coefficients data type, see Fixed-Point Data Types.

Dependencies

This parameter is editable only when Coefficient source is set to either Dialog parameters or Auto.

Coefficients Minimum — Minimum value of filter coefficients
`[]` (default) | scalar

Specify the minimum value of the filter coefficients. Simulink uses this minimum value to perform automatic scaling of fixed-point data types.

Coefficients Maximum — Maximum value of filter coefficients
`[]` (default) | scalar

Specify the maximum value of the filter coefficients. Simulink uses this maximum value to perform automatic scaling of fixed-point data types.

Product output — Product output data type
`Inherit: Inherit via internal rule` (default) | `Inherit: Same as input` | `fixdt(1,16,0)`

Product output specifies the data type of the output of a product operation in the FIR Rate Conversion block.

Inherit: Inherit via internal rule — The block inherits the product output data type based on an internal rule. For more information on this rule, see Inherit via Internal Rule.
Inherit: Same as input — The block specifies the product output data type to be the same as the input data type.
fixdt(1,16,0) — The block specifies a signed, binary-point, scaled, fixed-point data type with a word length of 16 bits and a fraction length of 0.

Alternatively, you can set the Product output data type by using the Data Type Assistant. To use the assistant, click the Show data type assistant button .

For more information on the data type assistant, see Specify Data Types Using Data Type Assistant (Simulink).

For a diagrammatic representation of how this block uses the product output data type, see Fixed-Point Data Types.

Dependencies

This parameter is editable only when Coefficient source is set to either Dialog parameters or Auto.

Accumulator — Accumulator data type
`Inherit: Inherit via internal rule` (default) | `Inherit: Same as input` | `Inherit: Same as product output` | `fixdt(1,16,0)`

Accumulator specifies the data type of the output of an accumulation operation in the FIR Rate Conversion block. For illustrations on how this block uses the accumulator data type, see Fixed-Point Data Types.

Inherit: Inherit via internal rule — The block inherits the accumulator data type based on an internal rule. For more information on this rule, see Inherit via Internal Rule.
Inherit: Same as input — The block specifies the accumulator data type to be the same as the input data type.
Inherit: Same as product output — The block specifies the accumulator data type to be the same as the product output data type.
fixdt(1,16,0) — The block specifies a signed, binary-point, scaled, fixed-point data type with a word length of 16 bits and a fraction length of 0.

Alternatively, you can set the Accumulator data type by using the Data Type Assistant. To use the assistant, click the Show data type assistant button.

For more information on the data type assistant, see Specify Data Types Using Data Type Assistant (Simulink).

Dependencies

This parameter is editable only when Coefficient source is set to either Dialog parameters or Auto.

Output — Output data type
`Inherit: Same as accumulator` (default) | `Inherit: Same as input` | `Inherit: Same as product output` | `fixdt(1,16,0)`

Output specifies the data type of the output of the FIR Rate Conversion block.

Inherit: Same as input — The block specifies the output data type to be the same as the input data type.
Inherit: Same as product output — The block specifies the output data type to be the same as the product output data type.
Inherit: Same as accumulator — The block specifies the output data type to be the same as the accumulator data type.
fixdt(1,16,0) — The block specifies a signed, binary-point, scaled, fixed-point data type with a word length of 16 bits and a fraction length of 0.

Alternatively, you can set the Output data type by using the Data Type Assistant. To use the assistant, click the Show data type assistant button .

For more information on the data type assistant, see Specify Data Types Using Data Type Assistant (Simulink).

For a diagrammatic representation of how this block uses the output data type, see Fixed-Point Data Types.

Dependencies

This parameter is editable only when Coefficient source is set to either Dialog parameters or Auto.

Output Minimum — Minimum value the block can output
`[]` (default) | scalar

Specify the minimum value the block can output. Simulink uses this minimum value to perform:

Simulation range checking. For more information, see Specify Signal Ranges (Simulink).
Automatic scaling of fixed-point data types.

Output Maximum — Maximum value block can output
`[]` (default) | scalar

Specify the maximum value the block can output. Simulink uses this maximum value to perform:

Simulation range checking. For more information, see Specify Signal Ranges (Simulink).
Automatic scaling of fixed-point data types.

Lock data type settings against changes by the fixed-point tools — Prevent fixed-point tools from overriding data types
`off` (default) | `on`

Select this parameter to prevent the fixed-point tools from overriding the data types you specify on the block dialog box.

Dependencies

This parameter appears only when Coefficient source is set to either Dialog parameters or Auto.

Block Characteristics

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

More About

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Specify FIR Filter Coefficients

When you select the Dialog parameters option, you use the FIR filter coefficients parameter to specify the numerator coefficients of the FIR filter transfer function H(z).

$H (z) = b_{0} + b_{1} z^{- 1} + ... + b_{N} z^{- N},$

You can generate the FIR filter coefficient vector, b = [b₀, b₁, …, b_N], using one of the DSP System Toolbox™ filter design functions such as designMultirateFIR, firnyquist, firgr, or firceqrip.

The coefficient vector you specify must have a length greater than the interpolation factor (N + 1 >L). The FIR filter must be a lowpass filter with a normalized cutoff frequency no greater than min(1/L,1/M). The block internally initializes all filter states to zero.

When you select the Auto mode, the block designs an FIR multirate filter with the decimation factor specified in Decimation factor and interpolation factor specified in Interpolation factor. The designMultirateFIR function designs the filter and returns the coefficients used by the block. For more information on the filter design algorithm, see Orfanidis [1].

Specify Resampling Rate

This section applies only to the single-rate processing mode when the Rate options parameter is set to Enforce single-rate processing.

You specify the resampling rate of the FIR Rate Conversion block using the Decimation factor and Interpolation factor parameters. For a P_i-by-Q matrix input, the Decimation factor M and the Interpolation factor L must satisfy these requirements:

M and L must be relatively prime integers. That is, the ratio M/L cannot be reduced to a ratio of smaller integers.
$\frac{M}{L} = \frac{P_{i}}{P_{o}}$ , where P_i and P_o are the integer frame sizes of the input and output, respectively.

You can satisfy the second requirement by setting the Decimation factor, M, to equal the input frame size P_i. When you do so, the output frame size P_o equals the Interpolation factor L.

By changing the frame size in this way, the block is able to hold the frame period constant (T_fi = T_fo) and achieve the desired conversion of the sample period, such that

$T_{s o} = \frac{M}{L} \times T_{s i}$

where T_so is the output sample period.

This figure shows how the FIR Rate Conversion block converts a 4-by-1 input with a sample period of 3/4 to a 3-by-1 output with a sample period of 1. The frame period (T_f) of 3 remains constant.

Frame-Based Processing

The FIR Rate Conversion block resamples 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 resamples 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. To resample the output while maintaining the input sample rate, the block resamples the data in each column of the input such that the frame length of the output has an upper bound size of ceil(LP/M), where L is the interpolation factor specified in the Interpolation factor parameter, P is the input frame length, and M is the decimation factor specified in the Decimation factor parameter.

In this mode, if you input a fixed-size signal (frame length does not change during simulation) and select the Allow arbitrary frame length for fixed-size input signals parameter, the input frame length can be arbitrary and does not have to be a multiple of the decimation factor. If you clear the Allow arbitrary frame length for fixed-size input signals parameter, the input frame length must be a multiple of the decimation factor.

In this mode, if you input a variable-size signal (frame length changes during simulation), the Allow arbitrary frame length for fixed-size input signals appears on the block dialog box but does not have any impact on the input frame length. You can input a variable-size signal of any frame length even if you do not select the Allow arbitrary frame length for fixed-size input signals parameter.

This table summarizes the support for arbitrary input frame length when you set Rate options to Enforce single-rate processing.

Input Signal	Block Support for this Signal	Support for Arbitrary Input Frame Length	Input Size	Output Size
Fixed-size input signal	Yes	When you select Allow arbitrary frame length for fixed-size input signals	P-by-Q	Upper bound size of `ceil`(LP/M)-by-Q
Variable-size input signal	Yes	Always	P-by-Q	Upper bound size of `ceil`(LP/M)-by-Q

When you set the Rate options parameter to Allow multirate processing, the input and output of the FIR Rate Conversion block are of the same size, but the sample rate of the output is L/M times that of the input. In this mode, the block treats a P-by-Q matrix input as Q independent channels. The block decimates each column of the input over time by keeping the frame size constant, and making the output frame period (T_fo) M/L times the input frame period (T_fo = (M/L)*T_fi).

In this mode, the block accepts only fixed-size signals and these signals can have an arbitrary frame length.

This table summarizes the support for arbitrary input frame length when you set Rate options to Allow multirate processing.

Input Signal	Block Support for this Signal	Support for Arbitrary Input Frame Length	Input Size	Output Size
Fixed-size input signal	Yes	Always	P-by-Q	P-by-Q
Variable-size input signal	No	Not applicable	Not applicable	Not applicable

Fixed-Point Data Types

This diagram shows the data types used within the FIR Rate Conversion block for fixed-point signals.

You can set the coefficient, product output, accumulator, and output data types in the block dialog box. The diagram shows that input data is stored in the input buffer in the same data type and scaling as the input. Filtered data resides in the output buffer in the output data type and scaling that you set in the block dialog. The block stores any initial conditions in the output buffer using the output data type and scaling that you set in the block dialog box.

The output of the multiplier is in the product output data type when at least one of the inputs to the multiplier is real. When both the inputs to the multiplier are complex, the result of the multiplication is in the accumulator data type. For details on how the complex multiplication is performed in the block, see Multiplication Data Types.

Note

When the block input is fixed point, all internal data types are signed fixed point.

Algorithms

The FIR rate converter is implemented efficiently using a polyphase structure.

To derive the polyphase structure, start with the transfer function of the FIR filter: This FIR filter is a combined anti-imaging and anti-aliasing filter.

$H (z) = b_{0} + b_{1} z^{- 1} + ... + b_{N} z^{- N},$

N+1 is the length of the FIR filter.

You can rearrange this equation as follows:

$H (z) = \begin{matrix} (b_{0} + b_{L} z^{- L} + b_{2 L} z^{- 2 L} + .. + b_{N - L + 1} z^{- (N - L + 1)}) + \\ z^{- 1} (b_{1} + b_{L + 1} z^{- L} + b_{2 L + 1} z^{- 2 L} + .. + b_{N - L + 2} z^{- (N - L + 1)}) + \\ \begin{matrix} ⋮ \\ z^{- (L - 1)} (b_{L - 1} + b_{2 L - 1} z^{- L} + b_{3 L - 1} z^{- 2 L} + .. + b_{N} z^{- (N - L + 1)}) \end{matrix} \end{matrix}$

L is the number of polyphase components, and its value equals the interpolation factor that you specify.

You can write this equation as:

$H (z) = E_{0} (z^{L}) + z^{- 1} E_{1} (z^{L}) + ... + z^{- (L - 1)} E_{L - 1} (z^{L})$

E₀(z^L), E₁(z^L), ..., E_L-1(z^L) are polyphase components of the FIR filter H(z).

Conceptually, the FIR rate converter contains an upsampler, followed by a combined anti-imaging, anti-aliasing FIR filter H(z), which is followed by a downsampler.

FIR rate converter contains an upsampler followed by a combined anti-imaging, anti-aliasing FIR filter, followed by a downsampler.

Replace H(z) with its polyphase representation.

Here is the multirate noble identity for interpolation.

Applying the noble identity for interpolation moves the upsampling operation to after the filtering operation. This move enables you to filter the signal at a lower rate.

You can replace the upsampling operator, delay block, and the adder with a commutator switch. To account for the downsampler that follows, the switch moves in steps of size M. The switch receives the first sample from branch 0 and moves in the counter clockwise direction, each time skipping M−1 branches.

As an example, consider a rate converter with L set to 5 and M set to 3. The polyphase components are E₀(z), E₁(z), E₂(z), E₃(z), and E₄(z). The switch starts on the first branch 0, skips branches 1 and 2, receives the next sample from branch 3, then skips branches 4 and 0, receives the next sample from branch 2, and so on. The sequence of branches from which the switch receives the data sample is [0, 3, 1, 4, 2, 0, 3, 1, ….].

The rate converter implements the L/M conversion by first applying the interpolation factor L to the incoming data, and using the commutator switch at the end to receive only 1 in M samples, effectively accounting for the downsampling factor M. Hence, the sample rate at the output of the FIR rate converter is Lfs/M.

References

[1] Orfanidis, Sophocles J. Introduction to Signal Processing. Upper Saddle River, NJ: Prentice-Hall, 1996.

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.

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

Version History

Introduced before R2006a

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R2022b: Support for arbitrary input frame length

Starting in R2022b, this block supports input signals with arbitrary frame lengths when the:

Input signal is a fixed-size signal (frame length does not change during simulation) and the block allows for multirate processing
Input signal is a fixed-size signal, the block enforces single-rate processing, and you select the Allow arbitrary frame length for fixed-size input signals parameter
Input signal is a variable-size signal (frame length changes during simulation)

When this block supports an arbitrary frame length input signal, the input frame length does not have to be a multiple of the decimation factor.

For more details, see Frame-Based Processing.

FIR Rate Conversion

Description

Examples

GSM Digital Down Converter in Simulink

Convert Sample Rate of Speech Signal

Ports

Input

Port_1(In1) — Input signal vector | matrix

Output

Port_1(Out1) — Rate converted signal vector | matrix

Parameters

Coefficient source — Mode of operation Auto (default) | Dialog parameters | Filter object

Main Tab

Interpolation factor — Interpolation factor 3 (default) | positive integer

Dependencies

FIR filter coefficients — FIR filter coefficients designMultirateFIR(3,2) (default) | vector

Dependencies

Decimation factor — Decimation factor 2 (default) | positive integer

Dependencies

Rate options — Enforce single-rate or allow multirate processing Enforce single-rate processing (default) | Allow multirate processing

Filter object — Filter object FRC (default) | dsp.FIRRateConverter System object

Dependencies

Allow arbitrary frame length for fixed-size input signals — Allow arbitrary frame length for fixed-size input signals off (default) | on

Dependency

View Filter Response — Visualize filter response button

Data Types Tab

Rounding mode — Rounding method Floor (default) | Ceiling | Convergent | Nearest | Round | Simplest | Zero

Dependencies

Saturate on integer overflow — Overflow handling method off (default) | on

Dependencies

Coefficients — Coefficients data type Inherit: Same word length as input (default) | fixdt(1,16) | fixdt(1,16,0)

Dependencies

Coefficients Minimum — Minimum value of filter coefficients [] (default) | scalar

Coefficients Maximum — Maximum value of filter coefficients [] (default) | scalar

Product output — Product output data type Inherit: Inherit via internal rule (default) | Inherit: Same as input | fixdt(1,16,0)

Dependencies

Accumulator — Accumulator data type Inherit: Inherit via internal rule (default) | Inherit: Same as input | Inherit: Same as product output | fixdt(1,16,0)

Dependencies

Output — Output data type Inherit: Same as accumulator (default) | Inherit: Same as input | Inherit: Same as product output | fixdt(1,16,0)

Dependencies

Output Minimum — Minimum value the block can output [] (default) | scalar

Output Maximum — Maximum value block can output [] (default) | scalar

Lock data type settings against changes by the fixed-point tools — Prevent fixed-point tools from overriding data types off (default) | on

Dependencies

Block Characteristics

More About

Specify FIR Filter Coefficients

Specify Resampling Rate

Frame-Based Processing

Fixed-Point Data Types

Algorithms

References

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

R2022b: Support for arbitrary input frame length

See Also

Functions

Objects

Blocks

Topics

Port_1(In1) — Input signal
vector | matrix

Port_1(Out1) — Rate converted signal
vector | matrix

Coefficient source — Mode of operation
Auto (default) | Dialog parameters | Filter object

Interpolation factor — Interpolation factor
`3` (default) | positive integer

FIR filter coefficients — FIR filter coefficients
`designMultirateFIR(3,2)` (default) | vector

Decimation factor — Decimation factor
`2` (default) | positive integer

Rate options — Enforce single-rate or allow multirate processing
`Enforce single-rate processing` (default) | `Allow multirate processing`

Filter object — Filter object
`FRC` (default) | `dsp.FIRRateConverter` System object

Allow arbitrary frame length for fixed-size input signals — Allow arbitrary frame length for fixed-size input signals
off (default) | on

View Filter Response — Visualize filter response
button

Rounding mode — Rounding method
`Floor` (default) | `Ceiling` | `Convergent` | `Nearest` | `Round` | `Simplest` | `Zero`

Saturate on integer overflow — Overflow handling method
off (default) | on

Coefficients — Coefficients data type
`Inherit: Same word length as input` (default) | `fixdt(1,16)` | `fixdt(1,16,0)`

Coefficients Minimum — Minimum value of filter coefficients
`[]` (default) | scalar

Coefficients Maximum — Maximum value of filter coefficients
`[]` (default) | scalar

Product output — Product output data type
`Inherit: Inherit via internal rule` (default) | `Inherit: Same as input` | `fixdt(1,16,0)`

Accumulator — Accumulator data type
`Inherit: Inherit via internal rule` (default) | `Inherit: Same as input` | `Inherit: Same as product output` | `fixdt(1,16,0)`

Output — Output data type
`Inherit: Same as accumulator` (default) | `Inherit: Same as input` | `Inherit: Same as product output` | `fixdt(1,16,0)`

Output Minimum — Minimum value the block can output
`[]` (default) | scalar

Output Maximum — Maximum value block can output
`[]` (default) | scalar

Lock data type settings against changes by the fixed-point tools — Prevent fixed-point tools from overriding data types
`off` (default) | `on`

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™.