Design second-order tunable notching and peaking IIR filter
Filtering / Filter Designs
dspfdesign
The Notch-Peak Filter block filters each channel of the input signal over time using a specified center frequency and 3 dB bandwidth. This block offers tunable filter design parameters, which enable you to tune the filter characteristics while the simulation is running.
The block designs the 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 the dsp.NotchPeakFilter
System object™ to the Simulink® environment.
The filter uses a coupled allpass structure to optimize joint computation of the peak
and notch response. For information on the algorithms used by the Notch-Peak filter
block, see the Algorithms section of dsp.NotchPeakFilter
.
Parameters or coefficients used to design the filter, specified as one of the following:
Bandwidth and center frequency
(default) — Design the filter using 3 dB
bandwidth (Hz) and Notch/Peak center
frequency (Hz).
Coefficients
— Design the
filter using Bandwidth coefficient and
Center frequency coefficient.
Quality factor and center frequency
— Design the filter using Quality
factor and Notch/Peak center frequency
(Hz).
This parameter is nontunable.
When you select this check box, the 3 dB bandwidth is input through the BW port. When you clear this check box, the 3 dB bandwidth is specified on the block dialog through the 3 dB bandwidth (Hz) parameter.
This parameter applies when you set Filter
specification to Bandwidth and center
frequency
.
3 dB bandwidth of the filter, specified as a finite positive numeric
scalar that is less than half the sample rate of the input signal. This
parameter applies when you set Filter specification to
Bandwidth and center frequency
, and clear the
Specify bandwidth from input port parameter. The
default is 2205
. This parameter is tunable.
When you select this check box, the center frequency is input through the Fc port. When you clear this check box, the center frequency is specified on the block dialog through the Notch/Peak center frequency (Hz) parameter.
This parameter applies when you set Filter
specification to Bandwidth and center
frequency
or Quality factor and center
frequency
.
Center frequency of the notch and peak of the filter, specified as a
finite positive numeric scalar that is less than half the sample rate of the
input signal. This parameter applies when you set Filter
specification to Bandwidth and center
frequency
or Quality factor and center
frequency
, and clear the Specify center
frequency from input port parameter. The default is
11025
. This parameter is tunable.
When you select this check box, the bandwidth coefficient is input through the port, BWCoeff. When you clear this check box, the bandwidth coefficient is specified on the block dialog through the Bandwidth coefficient parameter.
This parameter applies when you set Filter
specification to
Coefficients
.
Coefficient that determines the 3 dB bandwidth of the filter, specified as
a finite numeric scalar in the range [-1 1]
.
-1
corresponds to the maximum 3 dB
bandwidth (one-fourth the sample rate of the input
signal).
1
corresponds to the minimum bandwidth (0
Hz, that is, an allpass filter).
This parameter applies when you set Filter
specification to Coefficients
and
clear the Specify bandwidth coefficient from input port
parameter. The default is 0.72654
. This parameter is
tunable.
When you select this check box, the center frequency coefficient is input through the FcCoeff port. When you clear this check box, the center frequency coefficient is specified on the block dialog through the Center frequency coefficient parameter.
This parameter applies when you set Filter
specification to
Coefficients
.
Coefficient that determines the center frequency of the filter, specified
as a finite numeric scalar in the range [-1 1]
.
-1
corresponds to the minimum center
frequency (0
Hz).
1
corresponds to the maximum center
frequency (half the sample rate of the input signal).
This parameter applies when you set Filter
specification to Coefficients
and
clear the Specify center frequency coefficient from input
port parameter. The default is 0
, which
corresponds to quarter the sample rate of the input signal. This parameter
is tunable.
When you select this check box, the quality factor is input through the Q port. When you clear this check box, the quality factor is specified on the block dialog through the Quality factor parameter.
This parameter applies when you set Filter
specification to Quality factor and center
frequency
.
Quality factor of the notch and peak filter, specified as a real positive
scalar. The quality factor is defined as Notch/Peak center
frequency (Hz) / 3 dB bandwidth (Hz). A
higher quality factor corresponds to a narrower peak or dip. This parameter
applies when you set Filter specification to
Quality factor and center frequency
and clear
the Specify quality factor from input port parameter.
The default is 5
. This parameter is tunable.
Output of the filter block, specified as one of the following:
Notch and Peak
(default) —
The block outputs the notch and peak responses of the filter.
Notch
— The block outputs
the notch response of the filter.
Peak
— The block outputs the
peak response of the filter.
This parameter is nontunable.
When you select this check box, the block 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 value. 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 Notch-Peak 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 |
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Input |
|
Output |
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[1] Orfanidis, Sophocles J. Introduction to Signal Processing. Upper Saddle River, NJ: Prentice-Hall, 1996.