Biquad Filter
A model of biquadratic BIR filters.
blockType: BiquadFilter
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Path in the library: |
Description
Unit Biquad Filter independently filters each channel of the input signal using the specified biquadratic filter with infinite impulse response (IIR). When filter coefficients are specified in the parameters settings window, the unit implements static filters with fixed coefficients.
Ports
Input
#
In -
input data
vector | matrix
Details
Input data for a block, specified as a vector or matrix.
| Data types |
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| Support for complex numbers |
Yes |
#
Num -
numerator coefficients
matrix
Details
The coefficients of the numerator of the biquadratic filter given as a matrix 3 at , where is the number of sections of the biquadratic filter.
Dependencies
To use this port, set the parameters for parameter Coefficient source value Input port(s).
| Data types |
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| Support for complex numbers |
No |
#
Den -
denominator coefficients
matrix
Details
The denominator coefficients of the biquadratic filter given as matrix 2 at , where is the number of sections of the biquadratic filter.
Dependencies
To use this port, set the parameters to Coefficient source value Input port(s).
| Data types |
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| Support for complex numbers |
No |
Output
#
Out -
filtered output data
vector | matrix
Details
A filtered output signal returned as a vector or matrix.
The output signal dimension is always equal to the input signal dimension.
| Data types |
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| Support for complex numbers |
Yes |
Parameters
Main
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Coefficient source —
the source of the filter coefficients
Input port(s) | Dialog parameters
Details
Block Biquad Filter It can work in two modes:
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Input port(s)— The filter coefficients are supplied to the block through additional input ports, which are displayed on the block icon.:-
Num — coefficients of the numerator.
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Den — coefficients of the denominator.
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Dialog parameters— the filter coefficients are set through the block parameters.
| Values |
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| Default value |
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| Program usage name |
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| Tunable |
No |
| Evaluatable |
No |
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Filter structure —
filter structure
Direct form I | Direct form II
Details
Specify the filter structure.
| Values |
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| Default value |
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| Program usage name |
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| Tunable |
No |
| Evaluatable |
No |
#
SOS Matrix (Mx6) —
the matrix of the second-order section
Array of real numbers
Details
Set the matrix on 6, where — the number of sections in the second-order sectional filter (SOS). Each row of the SOS matrix contains the coefficients of the numerator and denominator ( and ) of the corresponding filter section:
Leading coefficients of the denominator are equal to one, regardless of their actual values. SOS matrix scaling is not applied if not equal to one.
Dependencies
To use this parameter, set for the parameter Coefficient source meaning Dialog parameters.
| Default value |
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| Program usage name |
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| Tunable |
No |
| Evaluatable |
Yes |
# Scale values — values of scale coefficients
Details
Specify the values of the scale factors to be used between the SOS sections. You can specify a scalar with a real value or a vector of length. , where – the second dimension of the SOS matrix.
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If a scalar is specified, its value sets the gain before the first section of the second-order filter. The other default gain values are `1'.
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If a vector is given from values, then each value defines a separate filter section. For example, the first element is the first gain value, the second element is the second gain value, and so on.
Dependencies
To use this parameter, set for the parameter Coefficient source meaning Dialog parameters.
| Default value |
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| Program usage name |
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| Tunable |
No |
| Evaluatable |
Yes |
#
Initial conditions on zeros side —
initial states on the side of zeros
Real number
Details
Specify the initial filter states on the side of the filter structure with zeros ( , , , …), if for the parameter Filter structure the value is set Direct form I.
Block Biquad Filter by default, it sets the internal states of the filter to zero. To set non-zero initial states for filter delays, use the parameter Initial conditions on zeros side.
The number of initial conditions that need to be set and the method of setting them are shown in the table of acceptable initial conditions.
| The initial condition | Description |
|---|---|
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The block sets the scalar value for all delay elements in the filter. |
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Each vector or element of the matrix sets a unique initial condition for the corresponding delay element in the corresponding channel. — number of sections, — number of input channels: * The length of the vector must be equal to the number of delay elements in the filter. . * The matrix should have as many rows as there are delay elements in the filter. . The matrix should also have one column for each input channel. |
Dependencies
To use this parameter, set for the parameter Filter structure meaning Direct form I.
| Default value |
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| Program usage name |
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| Tunable |
No |
| Evaluatable |
Yes |
#
Initial conditions on poles side —
initial states on the side of the poles
Real number
Details
Specify the initial filter states on the side of the filter structure with poles ( , , …), if for the parameter Filter structure the value is set Direct form I.
Block Biquad Filter by default, it sets the internal states of the filter to zero. To set non-zero initial states for filter delays, use the parameter Initial conditions on poles side.
The number of initial conditions that need to be set and the method of setting them are shown in the table of acceptable initial conditions.
| The initial condition | Description |
|---|---|
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The block sets the scalar value for all delay elements in the filter. |
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Each vector or element of the matrix sets a unique initial condition for the corresponding delay element in the corresponding channel. — number of sections, — number of input channels: * The length of the vector must be equal to the number of delay elements in the filter. . * The matrix should have as many rows as there are delay elements in the filter. . The matrix should also have one column for each input channel. |
Dependencies
To use this parameter, set for the parameter Filter structure meaning Direct form I.
| Default value |
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| Program usage name |
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| Tunable |
No |
| Evaluatable |
Yes |
#
Initial conditions —
initial states
Real number
Details
Specify the initial filter states if for the parameter Filter structure the value is set Direct form II.
Block Biquad Filter by default, it sets the internal states of the filter to zero. To set non-zero initial states for filter delays, use the parameter Initial conditions.
The number of initial conditions that need to be set and the method of setting them are shown in the table of acceptable initial conditions.
| The initial condition | Description |
|---|---|
|
The block sets the scalar value for all delay elements in the filter. |
|
Each vector or element of the matrix sets a unique initial condition for the corresponding delay element in the corresponding channel. — number of sections, — number of input channels: * The length of the vector must be equal to the number of delay elements in the filter. . * The matrix should have as many rows as there are delay elements in the filter. . The matrix should also have one column for each input channel. |
Dependencies
To use this parameter, set for the parameter Filter structure meaning Direct form II.
| Default value |
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| Program usage name |
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| Tunable |
No |
| Evaluatable |
Yes |
#
Scale values mode —
setting mode for scale coefficients
Assume all are unity and optimize
Details
When selecting an option Assume all are unity and optimize all scale factor values are deleted.
Dependencies
To use this parameter, set for the parameter Coefficient source meaning Input port(s).
| Values |
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| Default value |
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| Program usage name |
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| Tunable |
No |
| Evaluatable |
No |
#
Action when the a0 values of the SOS matrix are not one —
action if the values of a0 of the SOS matrix are not equal to one
None | Warning | Error
Details
Specify the action that the block should perform when the values of the SOS matrix are they are not equal to one. Values to choose from: Warning, None, Error.
When choosing None leading coefficients They are considered as a unit, regardless of their actual values. SOS matrix scaling is not applied if not equal to one.
Dependencies
To use this parameter, set for the parameter Coefficient source meaning Dialog parameters.
| Values |
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| Default value |
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| Program usage name |
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| Tunable |
No |
| Evaluatable |
No |
#
Optimize unity scale values —
optimization of scaling factors equal to one
Logical
Details
Select this option to optimize the simulation when one or more scale factor values are equal to one. In this case, the values of the individual scale factors are deleted.
Dependencies
To use this parameter, set for the parameter Coefficient source meaning Dialog parameters.
| Default value |
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| Program usage name |
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| Tunable |
No |
| Evaluatable |
No |
#
Input processing —
input data processing
Columns as channels (frame based) | Elements as channels (sample based)
Details
Specify the input data processing method. For input data in the form of a matrix on parameter value Columns as channels (frame based) This means that each column is treated as a separate channel. In this mode, the block creates instances of the same filter, each with its own independent status buffer. Each of the filters are processed input samples at each time step Engee.
Parameter value Elements as channels (sample based) This means that each element is treated as a separate channel. In this mode, the block creates instances of the same filter, each with its own independent status buffer. Each filter processes one input sample at each time step Engee.
For more information, see Signal processing by frames and counts.
| Values |
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| Default value |
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| Program usage name |
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| Tunable |
No |
| Evaluatable |
No |