Biquad Filter
A model of biquadratic BIR filters.
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.
| Типы данных |
|
| 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).
| Типы данных |
|
| 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).
| Типы данных |
|
| 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.
| Типы данных |
|
| Support for complex numbers |
Yes |
Parameters
Main
#
Coefficient source —
filter coefficient source
Input port(s) | Dialog parameters
Details
block Biquad Filter can operate in two modes:
-
Input port(s)- filter coefficients are supplied to the block through additional input ports, which are displayed on the block icon:-
Num - numerator coefficients.
-
Den - denominator coefficients.
-
-
Dialog parameters- filter coefficients are set through block parameters.
| Values |
|
| Default value |
|
| Program usage name |
|
| Tunable |
No |
| Evaluatable |
No |
#
Filter structure —
filter structure
Direct form I | Direct form II
Details
Specify the structure of the filter.
| Values |
|
| Default value |
|
| Program usage name |
|
| Tunable |
No |
| Evaluatable |
No |
#
SOS Matrix (Mx6) —
second-order section matrix
Array of real numbers
Details
Set the matrix to 6, where is the number of sections in the second-order section (SOS) filter. Each row of the SOS matrix contains the numerator and denominator coefficients ( and ) of the corresponding filter section:
The leading coefficients of the denominator are equal to one regardless of their actual values. SOS matrix scaling is not applied if is not equal to one.
Dependencies
To use this parameter, set the parameters to Coefficient source value Dialog parameters.
| Default value |
|
| Program usage name |
|
| Tunable |
No |
| Evaluatable |
Yes |
# Scale values — scaling factors
Details
Specify the scaling factor values to be used between SOS sections. You can specify a scalar with a real value or a vector of length , where is the second dimension of the SOS matrix.
-
If a scalar is specified, its value specifies the gain before the first section of the second order filter. Other gain values are set to
1by default. -
If a vector of values is specified, each value defines a different section of the filter. 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 parameter Coefficient source value Dialog parameters.
| Default value |
|
| Program usage name |
|
| Tunable |
No |
| Evaluatable |
Yes |
#
Initial conditions on zeros side —
initial states on the zero side
Real number
Details
Specify the initial states of the filter on the side of the filter structure with zeros ( , , , …), if the parameter Filter structure is set to Direct form I.
Block Biquad Filter by default sets the internal filter states to zero. To set non-zero initial states for filter delays, use the parameters Initial conditions on zeros side.
The number of initial conditions to be set and how to set them are given in the table of acceptable initial conditions.
| Initial condition | Description |
|---|---|
|
Block sets the scalar value for all delay elements in the filter. |
|
Each vector or matrix element 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 the number of delay elements in the filter . The matrix must also have one column for each input channel. |
Dependencies
To use this parameter, set the parameters to Filter structure value Direct form I.
| Default value |
|
| Program usage name |
|
| Tunable |
No |
| Evaluatable |
Yes |
#
Initial conditions on poles side —
initial states on the pole side
Real number
Details
Specify the initial states of the filter on the pole side of the filter structure ( , , …), if the parameter Filter structure is set to Direct form I.
Block Biquad Filter by default sets the internal filter states to zero. To set non-zero initial states for filter delays, use the parameters Initial conditions on poles side.
The number of initial conditions to be set and how to set them are given in the table of acceptable initial conditions.
| Initial condition | Description |
|---|---|
|
Block sets the scalar value for all delay elements in the filter. |
|
Each vector or matrix element 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 the number of delay elements in the filter . The matrix must also have one column for each input channel. |
Dependencies
To use this parameter, set the parameters to Filter structure value Direct form I.
| Default value |
|
| Program usage name |
|
| Tunable |
No |
| Evaluatable |
Yes |
#
Initial conditions —
initial states
Real number
Details
Specify the initial states of the filter, if the parameters Filter structure is set to Direct form II.
Block Biquad Filter by default sets the internal filter states to zero. To set non-zero initial states for filter delays, use the parameters Initial conditions.
The number of initial conditions to be set and how to set them are given in the table of acceptable initial conditions.
| Initial condition | Description |
|---|---|
|
Block sets the scalar value for all delay elements in the filter. |
|
Each vector or matrix element 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 the number of delay elements in the filter . The matrix must also have one column for each input channel. |
Dependencies
To use this parameter, set parameter Filter structure value Direct form II.
| Default value |
|
| Program usage name |
|
| Tunable |
No |
| Evaluatable |
Yes |
#
Scale values mode —
scaling factor setting mode
Assume all are unity and optimize
Details
If you select the option Assume all are unity and optimize all values of scaling factors are deleted.
Dependencies
To use this parameter, set the parameters to Coefficient source value Input port(s).
| Values |
|
| Default value |
|
| Program usage name |
|
| 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 to be performed by the unit when the values of the SOS matrix are not equal to one. Values to select: Warning, None, Error.
When selecting None the leading coefficients are treated as one, regardless of their actual values. Scaling of the SOS matrix is not applied if is not equal to one.
Dependencies
To use this parameter, set the parameter Coefficient source value Dialog parameters.
| Values |
|
| Default value |
|
| Program usage name |
|
| Tunable |
No |
| Evaluatable |
No |
#
Optimize unity scale values —
optimisation of scaling factors equal to unity
Logical
Details
Select this check box to optimise the simulation when one or more scale factor values are equal to one. In this case, the unit scale factor values are removed.
Dependencies
To use this parameter, set parameter Coefficient source value Dialog parameters.
| Default value |
|
| Program usage name |
|
| Tunable |
No |
| Evaluatable |
No |
#
Input processing —
input data processing
Columns as channels (frame based) | Elements as channels (sample based)
Details
Specify the method of input data processing. For input data in the form of a matrix to the value of the parameters Columns as channels (frame based) 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 state buffer. Each of the filters processes input samples at each Engee time step.
The value of the parameters Elements as channels (sample based) 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 state buffer. Each filter processes one input sample at each Engee time step.
| Values |
|
| Default value |
|
| Program usage name |
|
| Tunable |
No |
| Evaluatable |
No |