Design parametric equalizer
Note
The Parametric Equalizer block has been replaced by the Parametric EQ Filter block. Existing instances of the Parametric Equalizer block will continue to operate. For new models, use the Parametric EQ Filter block.
Filtering / Filter Designs
dspfdesign
This block brings the filter design capabilities of the filterbuilder
function to the Simulink^{®} environment.
See Parametric Equalizer Filter Design — Main Pane for more information about the parameters of this block. The Data Types and Code Generation panes are not available for blocks in the DSP System Toolbox™ Filter Designs library.
Parameters of this block that do not change filter order or structure are tunable.
This button opens the Filter Visualization Tool (fvtool
) from the
Signal Processing Toolbox™ product. You can use the tool to display:
Magnitude response, phase response, and group delay in the frequency domain.
Impulse response and step response in the time domain.
Polezero information.
The tool also helps you evaluate filter performance by providing information about filter order, stability, and phase linearity. For more information on FVTool, see the Signal Processing Toolbox documentation.
Select Minimum
to design a minimum order
filter that meets the design specifications, or
Specify
to enter a specific filter order.
The order mode also affects the possible frequency constraints, which in
turn limit the gain specifications. For example, if you specify a
Minimum
order filter, the available
frequency constraints are:
Center frequency, bandwidth, passband
width
Center frequency, bandwidth, stopband
width
If you select Specify
, the available
frequency constraints are:
Center frequency,
bandwidth
Center frequency, quality
factor
Shelf type, cutoff frequency, quality
factor
Shelf type, cutoff frequency, shelf slope
parameter
Low frequency, high
frequency
Specify the filter order. This parameter is enabled only if the
Order mode is set to
Specify
.
Depending on the filter order, the possible frequency constraints change. Once you choose the frequency constraints, the input boxes in this area change to reflect the selection.
Select the specification to represent the frequency constraints. The following options are available:
Center frequency, bandwidth, passband
width
(available for minimum order
only)
Center frequency, bandwidth, stopband
width
(available for minimum order
only)
Center frequency, bandwidth
(available for a specified order only)
Center frequency, quality
factor
(available for a specified order
only)
Shelf type, cutoff frequency, quality
factor
(available for a specified order
only)
Shelf type, cutoff frequency, shelf slope
parameter
(available for a specified order
only)
Low frequency, high frequency
(available for a specified order only)
Select the frequency units from the available drop down list
(Normalized
,
Hz
, kHz
,
MHz
, GHz
). If
Normalized
is selected, then the
Input Fs box is disabled for input.
Enter the input sampling frequency. This input box is disabled for
input if Normalized
is selected in the
Frequency units input box.
Enter the center frequency in the units specified by the value in Frequency units.
The bandwidth determines the frequency points at which the filter
magnitude is attenuated by the value specified as the
Bandwidth gain in the Gain
specifications section. By default, the
Bandwidth gain defaults to
db(sqrt(.5))
, or –3 dB relative to the center
frequency. The Bandwidth property only applies when
the Frequency constraints are: Center
frequency, bandwidth, passband width
,
Center frequency, bandwidth, stopband
width
, or Center frequency,
bandwidth
.
The passband width determines the frequency points at which the filter
magnitude is attenuated by the value specified as the Passband
gain in the Gain specifications
section. This option is enabled only if the filter is of minimum order,
and the frequency constraint selected is Center frequency,
bandwidth, passband width
.
The stopband width determines the frequency points at which the filter
magnitude is attenuated by the value specified as the Stopband
gain in the Gain specifications
section. This option is enabled only if the filter is of minimum order,
and the frequency constraint selected is Center frequency,
bandwidth, stopband width
.
Enter the low frequency cutoff. This option is enabled only if the
filter order is user specified and the frequency constraint selected is
Low frequency, high frequency
. The filter
magnitude is attenuated by the amount specified in Bandwidth
gain.
Enter the high frequency cutoff. This option is enabled only if the
filter order is user specified and the frequency constraint selected is
Low frequency, high frequency
. The filter
magnitude is attenuated by the amount specified in Bandwidth
gain.
Depending on the filter order and frequency constraints, the possible gain constraints change. Also, once you choose the gain constraints the input boxes in this area change to reflect the selection.
Select the specification array to represent gain constraints, and remember that not all of these options are available for all configurations. The following is a list of all available options:
Reference, center frequency, bandwidth,
passband
Reference, center frequency, bandwidth,
stopband
Reference, center frequency, bandwidth,
passband, stopband
Reference, center frequency,
bandwidth
Specify the gain units either dB
or
squared
. These units are used for all
gain specifications in the dialog box.
The reference gain determines the level to which the filter magnitude attenuates in Gain units. The reference gain is a floor gain for the filter magnitude response. For example, you may use the reference gain together with the Center frequency gain to leave certain frequencies unattenuated (reference gain of 0 dB) while boosting other frequencies.
Specifies the gain in Gain units at which the
bandwidth is defined. This property applies only when the
Frequency constraints specification contains a
bandwidth
parameter, or is Low
frequency, high frequency
.
Specify the center frequency in Gain units
The passband gain determines the level in Gain units at which the passband is defined. The passband is determined either by the Passband width value, or the Low frequency and High frequency values in the Frequency specifications section.
The stopband gain is the level in Gain units at
which the stopband is defined. This property applies only when the
Order mode is minimum and the
Frequency constraints are Center
frequency, bandwidth, stopband width
.
The boost/cut gain applies only when the designing a shelving filter.
Shelving filters include the Shelf type
parameter in the Frequency constraints
specification. The gain in the passband of the shelving filter is
increased by Boost/cut gain dB from a
floor gain of 0 dB.
Select the design method from the dropdown list. Different methods are available depending on the chosen filter constraints.
Select the check box to scale the filter coefficients.
Specify filter structure. Choose from:
Directform I SOS
Directform II SOS
Directform I transposed SOS
Directform II transposed SOS
Select this check box to implement the filter as a subsystem of basic Simulink blocks. Clear the check box to implement the filter as a highlevel subsystem. By default, this check box is cleared.
The highlevel implementation provides better compatibility across various filter structures, especially filters that would contain algebraic loops when constructed using basic elements. On the other hand, using basic elements enables the following optimization parameters:
Optimize for zero gains — Terminate chains that contain Gain blocks with a gain of zero.
Optimize for unit gains — Remove Gain blocks that scale by a factor of one.
Optimize for delay chains — Substitute delay chains made up of n unit delays with a single delay by n.
Optimize for negative gains — Use subtraction in Sum blocks instead of negative gains in Gain blocks.
Select this check box to scale unit gains between sections in SOS filters. This parameter is available only for SOS filters.
Specify how the block should process the input. The available options may vary depending on he settings of the Filter Structure and Use basic elements for filter customization parameters. You can set this parameter to one of the following options:
Columns as channels (frame based)
—
When you select this option, the block treats each column of the input
as a separate channel.
Elements as channels (sample based)
—
When you select this option, the block treats each element of the
input as a separate channel.
Note
The Inherited (this choice will be removed —
see release notes)
option will be removed in a future
release. See FrameBased Processing in the DSP System Toolbox Release
Notes for more information.
When the Filter type parameter specifies a multirate filter, select the rate processing rule for the block from following options:
Enforce singlerate processing
— When you select this option, the block maintains the
sample rate of the input.
Allow multirate processing
—
When you select this option, the block adjusts the rate at the
output to accommodate an increased or reduced number of samples.
To select this option, you must set the Input
processing parameter to Elements as
channels (sample based)
.
Select this check box to enable the specification of coefficients using MATLAB^{®} variables. The available coefficient names differ depending on the filter structure. Using symbolic names allows tuning of filter coefficients in generated code. By default, this check box is cleared.
Port  Supported Data Types 

Input 

Output 
