Design tunable bandwidth IIR filter
Filtering / Filter Designs
dspfdesign
The Variable Bandwidth IIR Filter block filters each channel of the input signal over time using specified IIR filter specifications. This block offers tunable filter design parameters, which enable you to tune the filter characteristics while the simulation is running.
The block designs the IIR filter according to the filter parameters set in the block dialog box. The output port properties, such as datatype, complexity, and dimension, are identical to the input port properties.
Each column of the input signal is treated as a separate channel. If the input is a two-dimensional signal, the first dimension represents the channel length (or frame size) and the second dimension represents the number of channels. If the input is a one-dimensional signal, then it is interpreted as a single channel.
This block supports variable-size input, enabling you to change the channel length during simulation. To enable variable-size input, clear the Inherit sample rate from input check box. The number of channels must remain constant.
This block brings the capabilities of dsp.VariableBandwidthIIRFilter
System object™ to the Simulink® environment.
The IIR filter is designed using the elliptical method. The IIR filter is tuned using
IIR spectral transformations based on allpass filters. For more information on the
algorithms used by the Variable Bandwidth IIR Filter block, see the Algorithms section of dsp.VariableBandwidthIIRFilter
.
Type of IIR filter. You can set this parameter to:
Lowpass
(default)
Highpass
Bandpass
Bandstop
This parameter is nontunable.
Order of the IIR filter, specified as a positive integer scalar. The
default is 8
. This parameter is nontunable.
When you select this check box, the filter passband frequency is input through the Fp port. When you clear this check box, the passband frequency is specified on the block dialog through the Filter passband frequency (Hz) parameter.
This parameter applies when you set Filter type to
Lowpass
or
Highpass
.
Passband frequency of the IIR filter, specified as a real positive scalar
that is less than half the sample rate of the input signal. This parameter
applies when you set Filter type to
Lowpass
or
Highpass
, and clear the Specify
passband frequency from input port parameter. The default is
1000
. This parameter is tunable.
When you select this check box, the center frequency of the IIR filter is input through the Fc port. When you clear this check box, the center frequency is specified on the block dialog through the Filter center frequency (Hz) parameter.
This parameter applies when you set Filter type to
Bandpass
or
Bandstop
.
Center frequency of the IIR filter, specified as a real positive scalar
that is less than half the sample rate of the input signal. This parameter
applies when you set Filter type to
Bandpass
or
Bandstop
, and clear the Specify
center frequency from input port parameter. The default is
10000
. This parameter is tunable.
When you select this check box, the bandwidth of the IIR filter is input through the BW port. When you clear this check box, the filter bandwidth is specified on the block dialog through the Filter bandwidth (Hz) parameter.
This parameter applies when you set Filter type to
Bandpass
or
Bandstop
.
Bandwidth of the IIR filter, specified as a real positive scalar that is
less than half the sample rate of the input signal. This parameter applies
when you set Filter type to
Bandpass
or
Bandstop
, and clear the Specify
bandwidth from input port parameter. The default is
2000
. This parameter is tunable.
Passband ripple of the IIR filter, specified as a real positive scalar.
The default is 1
. This parameter is nontunable.
Stopband attenuation of the IIR filter, specified as a real positive
scalar. The default is 60
. This parameter is
nontunable.
When you select this check box, the block’s sample rate is computed as N / Ts, where N is the frame size of the input signal and Ts is the sample time of the input signal. When you clear this check box, the block’s sample rate is the value specified in Input sample rate (Hz). By default, this check box is selected.
Sample rate of the input signal, specified as a positive scalar. The
default is 44100
. This parameter applies when you clear
the Inherit sample rate from input check box. This
parameter is nontunable.
Opens the Filter Visualization Tool FVTool and displays the magnitude/phase response of the Variable Bandwidth IIR Filter. The response is based on the block dialog box parameters. Changes made to these parameters update FVTool.
To update the magnitude response while FVTool is running, modify the dialog box parameters and click Apply.
Type of simulation to run. You can set this parameter to:
Code generation
(default)
Simulate model using generated C code. The first time you run
a simulation, Simulink generates C code for the block. The C code is
reused for subsequent simulations, as long as the model does not
change. This option requires additional startup time but
provides faster simulation speed
than Interpreted
execution
.
Interpreted execution
Simulate model using the MATLAB® interpreter. This option shortens startup
time but has slower simulation speed than Code
generation
.
Port | Supported Data Types |
---|---|
Input |
|
Output |
|
[1] A. G. Constantinides. "Spectral Transformations for Digital Filters." Proceedings of the Institution of Electrical Engineers 117, no. 8 (1970):1585-1590.
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dsp.VariableBandwidthFIRFilter | DSP System Toolbox |
dsp.VariableBandwidthIIRFilter | DSP System Toolbox |