Bandpass Filter
Design bandpass filter
- Library:
DSP System Toolbox / Filtering / Filter Designs
Description
This block brings the filter design capabilities of the filterbuilder function to the Simulink® environment.
Ports
Input
Port_1 — Input signal
scalar | vector | matrix
Input signal to filter, specified as a scalar, vector, or matrix.
Data Types: single | double
Output
Port_1 — Filtered output signal
scalar | vector | matrix
Filtered output signal, specified as a scalar, vector, or matrix.
Data Types: single | double
Parameters
View Filter Response — Open Filter Visualization Tool
button
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.
Pole-zero 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.
Impulse response — FIR or IIR filter
FIR (default) | IIR
Choose to implement an FIR or
IIR filter.
Note
The design methods and structures for FIR filters are not the same as the methods and structures for IIR filters.
Order mode — Mode of specifying filter order
Minimum (default) | Specify
Select Minimum to have the block implement a
filter with minimum order. When you select
Specify, you must enter the filter order
using the Order parameter.
Tip
When you set the Impulse response to
IIR, you can specify different numerator and
denominator orders. To specify a different denominator order, select the
Denominator order check box.
Order — Filter order
20 (default) | positive integer
Specify the filter order as a positive integer.
Dependencies
To enable this parameter, set Order mode to
Specify.
Denominator order — Specify denominator order
off (default) | on
Select this check box to specify a different denominator order. When you select this check box, you can specify the denominator order as a positive integer in the resulting text box.
Dependencies
To enable this parameter, set the Impulse
response to IIR and the
Order mode to
Specify.
Filter type — Type of filter
Single-rate (default) | Decimator | Interpolator | Sample-rate converter
Select the type of filter to implement. Your choice determines the type of filter and the design methods and structures that are available to implement your filter.
Dependencies
Selecting
DecimatororInterpolatoractivates the Decimation Factor or the Interpolation Factor options respectively.Selecting
Sample-rate converteractivates both factors.
Decimation Factor — Decimation factor
2 (default) | positive integer
Specify the decimation factor as a positive integer.
Dependencies
To enable this parameter, set the Filter type to
Decimator or Sample-rate
converter.
Interpolation Factor — Interpolation factor
2 (default) | positive integer
Specify the interpolation factor as a positive integer.
Dependencies
To enable this parameter, set the Filter type to
Interpolator or Sample-rate
converter.
Frequency constraints — Frequency response constraints
Passband and stopband
edges (default) | Passband edges | Half power (3dB) frequencies | Half power (3dB) frequencies and passband
width | Half power (3dB) frequencies and stopband
width | Cutoff (6dB) frequencies
When you set the Order mode to
Specify, this parameter allows you to choose
the filter features that the block uses to define the frequency response
characteristics. Depending on the Impulse response you
choose, you can set the Frequency constraints to one
of:
Passband and stopband edges— Specify the frequencies for the edges for the stop- and passbands.Passband edges— For IIR filters, define the filter by specifying frequencies for the edges of the passband.Stopband edges— For IIR filters, define the filter by specifying frequencies for the edges of the stopbands.Half power (3dB) frequencies— For IIR filters, define the filter response by specifying the locations of the 3 dB points. The 3 dB point is the frequency for the point three decibels below the passband value.Half power (3dB) frequencies and passband width— For IIR filters, define the filter by specifying frequencies for the 3 dB points in the filter response and the width of the passband.Half power (3dB) frequencies and stopband width— For IIR filters, define the filter by specifying frequencies for the 3 dB points in the filter response and the width of the stopband.Cutoff (6dB) frequencies— For FIR filters, define the filter response by specifying the locations of the 6 dB points. The 6 dB point is the frequency for the point 6 dB below the passband value.
Dependencies
To enable this parameter, set the Order mode to
Specify. The available
Frequency constraints will depend on whether
the Impulse response is
FIR or
IIR.
Frequency units — Frequency units
Normalized (0 to 1) (default) | Hz | kHz | MHz | GHz
Use this parameter to specify whether your frequency settings are
normalized or in absolute frequency. Select Normalized (0 to
1) to enter frequencies in normalized form. To enter
frequencies in absolute values, select one of the frequency units from the
drop-down list—Hz,
kHz, MHz, or
GHz.
Input sample rate — Input sample rate
2 (default) | positive scalar
Fs, specified in the units you selected for
Frequency units, defines the sampling frequency at
the filter input. When you provide an input sampling frequency, all
frequencies in the specifications are in the selected units as well.
Dependencies
To enable this parameter, set Filter type to
Single-rate,
Decimator, or Sample-rate
converter and Frequency units to
one of the unit options (Hz,
kHz, MHz, or
GHz).
Output sample rate — Output sample rate
2 (default) | positive scalar
When you design an interpolator, Fs represents the sampling frequency
at the filter output.
Dependencies
To enable this parameter, set Filter type to
Interpolator and Frequency
units to one of the unit options
(Hz, kHz,
MHz, or
GHz).
Stopband frequency 1 — Frequency at edge of end of first stopband
0.35 (default) | positive scalar
Enter the frequency at the edge of the end of the first stopband. Specify the value in either normalized frequency units or the absolute units you select in Frequency units.
Passband frequency 1 — Frequency at edge of start of passband
0.45 (default) | positive scalar
Enter the frequency at the edge of the start of the passband. Specify the value in either normalized frequency units or the absolute units you selected for Frequency units.
Passband frequency 2 — Frequency at edge of end of passband
.55 (default) | positive scalar
Enter the frequency at the edge of the end of the passband. Specify the value in either normalized frequency units or the absolute units you select in Frequency units.
Stopband frequency 2 — Frequency at edge of start of second stopband
.65 (default) | positive scalar
Enter the frequency at the edge of the start of the second stopband. Specify the value in either normalized frequency units or the absolute units you select in Frequency units.
Half power (3dB) frequency 1 — Lower frequency 3 dB point
.4 (default) | positive scalar
Specify the lower frequency 3 dB point as a positive scalar between zero and one.
Dependencies
To enable this parameter, set Impulse response to
IIR, Order mode to
Specify, and Frequency
constraints to Half power (3dB)
frequencies, Half power (3dB) frequencies
and passband width, or Half power (3dB)
frequencies and stopband width.
Half power (3dB) frequency 2 — Higher frequency 3 dB point
.6 (default) | positive scalar
Specify the higher frequency 3 dB point as a positive scalar between zero and one.
Dependencies
To enable this parameter, set Impulse response to
IIR, Order mode to
Specify, and Frequency
constraints to Half power (3dB)
frequencies, Half power (3dB) frequencies
and passband width, or Half power (3dB)
frequencies and stopband width.
Cutoff (6dB) frequency 1 — Lower frequency 6 dB point
.4 (default) | positive scalar
Specify the lower frequency 6 dB point as a positive scalar between zero and one.
Dependencies
To enable this parameter, set Frequency
constraints to Cutoff (6dB)
frequencies.
Cutoff (6dB) frequency 2 — Higher frequency 6 dB point
.6 (default) | positive scalar
Specify the higher frequency 6 dB point as a positive scalar between zero and one.
Dependencies
To enable this parameter, set Frequency
constraints to Cutoff (6dB)
frequencies.
Passband width — Passband width
.15 (default) | positive scalar
Specify the width of the passband as a positive scalar, in units corresponding to the Frequency units parameter.
Dependencies
To enable this parameter, set Frequency
constraints to Half power (3dB) frequencies
and passband width.
Stopband width — Width of stopband
.25 (default) | positive scalar
Specify the width of the stopband as a positive scalar, in units corresponding to the Frequency units parameter.
Dependencies
To enable this parameter, set Frequency
constraints to Half power (3dB) frequencies
and stopband width.
Magnitude constraints — Magnitude constraints
Unconstrained (default) | Constrained bands | Passband ripple | Passband ripple and stopband
attenuation | Stopband attenuation
Specify the magnitude constraints for the filter design.
Dependencies
To enable this parameter, set Order mode to
Specify. The available options depend on
the value of the Frequency constraints
parameters.
Magnitude units — Units for magnitude specifications
dB (default) | Linear | Squared
Specify the units for any parameter you provide in magnitude specifications:
Linear— Specify the magnitude in linear units.dB— Specify the magnitude in decibels (default).Squared— Specify the magnitude in squared units.
Dependencies
To enable this parameter, set Order mode to
Minimum.
Stopband attenuation 1 — Filter attenuation in first stopband
60 (default) | real-valued positive scalar
Enter the filter attenuation in the first stopband in the units you choose for Magnitude units. Values must be real, positive scalars. If you are specifying values in linear units, they must be smaller than 1.
Dependencies
To enable this parameter, set the Order mode to
Minimum.
Passband ripple — Allowable filter ripple in passband
1 (default) | real-valued positive scalar
Enter the filter ripple allowed in the passband in the units you choose for Magnitude units. Values must be real, positive scalars. If you are specifying values in linear units, they must be smaller than 1.
Dependencies
To enable this parameter, set the Order mode to
Minimum.
Stopband attenuation 2 — Filter attenuation in second stopband
60 (default) | real-valued positive scalar
Enter the filter attenuation in the second stopband in the units you choose for Magnitude units. Values must be real, positive scalars. If you are specifying values in linear units, they must be smaller than 1.
Dependencies
To enable this parameter, set the Order mode to
Minimum.
Design method — Filter design method
Equiripple (default) | Kaiser window | Butterworth | Chebyshev type I | Chebyshev type II | Elliptic
Lists the design methods available for the frequency and magnitude
specifications you entered. When you change the specifications for a filter,
such as changing the impulse response, the methods available to design
filters changes as well. The default IIR design method is usually
Butterworth, and the default FIR method is
Equiripple.
Scale SOS filter coefficients to reduce chance of overflow — Scale filter coefficients
on (default) | off
Selecting this parameter directs the design to scale the filter coefficients to reduce the chances that the inputs or calculations in the filter overflow and exceed the representable range of the filter. Clearing this option removes the scaling.
Dependencies
To enable this parameter, set Impulse response to
IIR.
Density factor — Density factor
16 (default) | positive scalar
Density factor controls the density of the frequency grid over which the design method
optimization evaluates your filter response function. The number of equally
spaced points in the grid is the value you enter for Density
factor times filter order + 1.
Increasing the value creates a filter that more closely approximates an ideal equiripple
filter but increases the time required to design the filter. The default
value of 16 represents a reasonable balance between the
accurate approximation to the ideal filter and the time to design the
filter.
Dependencies
To enable this parameter, set Impulse response to
FIR and Design
method to Equiripple.
Phase constraint — Phase constraint
Linear (default) | Maximum | Minimum
Specify the phase constraint of the filter as Linear,
Maximum, or Minimum.
Dependencies
To enable this parameter, set Impulse response to
FIR and Design
method to Equiripple.
Match exactly — Match passband, stopband, or both
Stopband (default) | Passband | Both
Specifies that the resulting filter design matches either the passband, stopband, or both bands.
Dependencies
To enable this parameter, set Impulse response to
IIR.
Minimum order — Minimum filter order
Any (default) | Even | Odd
When you select this parameter, the design method determines and designs a minimum order filter to meet your specifications.
Dependencies
To enable this parameter, set Impulse response to
FIR and Order mode
to Minimum.
Structure — Filter structure
Direct-form FIR (default) | Direct-form FIR transposed | Direct-form symmetric FIR | Cascade minimum-multiplier allpass | Cascade wave digital filter allpass | Direct-form I SOS | Direct-form I transposed SOS | Direct-form II SOS | Direct-form II transposed SOS
For the filter specifications and design method you select, this parameter lists the filter structures available to implement your filter. By default, FIR filters use direct-form structure, and IIR filters use direct-form II filters with SOS.
Use basic elements to enable filter customization — Implement filter with basic Simulink blocks
off (default) | on
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 high-level subsystem.
The high-level implementation provides better compatibility across various filter structures, especially filters that would contain algebraic loops when constructed using basic elements.
Dependencies
When you select this check box, the block 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.
Optimize for unit-scale values — Optimize unit scale values
off (default) | on
Select this check box to scale unit gains between sections in SOS filters.
Dependencies
To enable this parameter, set Impulse response to
IIR.
Rate options — Enforce single-rate or allow multirate processing
Enforce single-rate
processing (default) | Allow multirate processing
When the Filter type parameter specifies a multirate filter, select the rate processing rule for the block:
Enforce single-rate 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.
Dependencies
To enable this parameter, set the Impulse
response to FIR and set
Filter type to a multirate filter.
Use symbolic names for coefficients — Specify coefficients with MATLAB variables
off (default) | on
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.
Block Characteristics
Data Types |
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Multidimensional Signals |
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Variable-Size Signals |
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