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designBandstopFIR

Design and implement bandstop FIR filter

Since R2023b

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Syntax

B = designBandstopFIR
B = designBandstopFIR(Name=Value)

Description

example

B = designBandstopFIR designs a bandstop FIR filter with the filter order of 100, center frequency of 0.5, bandwidth of 0.1, and a Hamming window. B is a vector of filter coefficients of length 101.

The System object™ argument is false by default. To implement the filter, assign the filter coefficients in B to a dsp.FIRFilter object.

example

B = designBandstopFIR(Name=Value) specifies options using one or more name-value arguments.

For example, B = designBandstopFIR(FilterOrder=30,CenterFrequency=0.4,Window="hann",SystemObject=true) designs a bandstop FIR filter with the filter order of 30, center frequency of 0.4, and a Hann window. As the SystemObject argument is true, the function designs and implements the bandstop FIR filter. B is a dsp.FIRFilter System object in this case.

When you specify only a partial list of filter parameters, the function designs the filter by setting the other design parameters to their default values.

Examples

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Open Live Script

Create a dsp.FIRFilter object, and set the NumeratorSource property to 'Input port' so that you can vary the FIR filter coefficients through the input during simulation.

firFilt = dsp.FIRFilter(NumeratorSource="Input port")
firFilt = 
  dsp.FIRFilter with properties:

            Structure: 'Direct form'
      NumeratorSource: 'Input port'
    InitialConditions: 0

  Use get to show all properties

Create a spectrumAnalyzer object to visualize the spectra of the input and output signals.

spectrumScope = spectrumAnalyzer(SampleRate=44100,PlotAsTwoSidedSpectrum=false,...
    ChannelNames=["Input Signal","Filtered Signal"]);

Create a dsp.DynamicFilterVisualizer object to visualize the magnitude response of the varying filter.

filterViz = dsp.DynamicFilterVisualizer(NormalizedFrequency=true);

Stream in random data and filter the signal using the dsp.FIRFilter object. Use the designBandstopFIR function to design the filter coefficients. By default, this function returns a vector of FIR filter coefficients. Assign these coefficients to the dsp.FIRFilter object.

Vary the center frequency of the filter during simulation. The designBandstopFIR function redesigns the coefficients based on the updated filter specifications. Pass these updated coefficients to the FIR filter. Visualize the spectra of the input and filtered signals using the spectrum analyzer.

Fc = 0.5;
for idx = 1:500
    num = designBandstopFIR(FilterOrder=30,CenterFrequency=Fc,Bandwidth=0.2,Window="hann");
    x = randn(1024,1);
    y = firFilt(x,num);
    spectrumScope(x,y);
    filterViz(num);
    Fc = Fc + 0.0001;
end

Open Live Script

Design and implement a bandstop FIR filter object using the designBandstopFIR function. The function returns a dsp.FIRFilter object when you set the SystemObject argument to true.

firFilt = designBandstopFIR(FilterOrder=30,CenterFrequency=0.5,Bandwidth=0.3,Window="hann",...
    SystemObject=true)
firFilt = 
  dsp.FIRFilter with properties:

            Structure: 'Direct form'
      NumeratorSource: 'Property'
            Numerator: [0 1.5217e-04 -3.2176e-19 0.0030 -2.0714e-17 -0.0158 1.1893e-17 0.0208 -3.3379e-18 0.0213 -2.0490e-17 -0.1252 3.4516e-17 0.2442 -1.7349e-17 0.7027 -1.7349e-17 0.2442 3.4516e-17 -0.1252 -2.0490e-17 0.0213 ... ] (1x31 double)
    InitialConditions: 0

  Use get to show all properties

Create a dsp.DynamicFilterVisualizer object to visualize the magnitude response of the varying filter.

filterViz = dsp.DynamicFilterVisualizer(NormalizedFrequency=true);
filterViz(firFilt)

Create a spectrumAnalyzer object to visualize the spectra of the input and output signals.

spectrumScope = spectrumAnalyzer(SampleRate=44100,PlotAsTwoSidedSpectrum=false,...
    ChannelNames=["Input Signal","Filtered Signal"]);

Stream in random data and filter the signal using the dsp.FIRFilter object. Visualize the spectra of the input and filtered signals using the spectrum analyzer.

for idx = 1:500
    x = randn(1024,1);
    y = firFilt(x);
    spectrumScope(x,y);
end

Input Arguments

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Name-Value Arguments

Specify optional pairs of arguments as Name1=Value1,...,NameN=ValueN, where Name is the argument name and Value is the corresponding value. Name-value arguments must appear after other arguments, but the order of the pairs does not matter.

Example: designBandstopFIR(FilterOrder=30,CenterFrequency=0.3,Bandwidth=0.2)

Order of the bandstop FIR filter, N, specified as an even nonnegative integer.

Data Types: single | double | int8 | int16 | int32 | int64 | uint8 | uint16 | uint32 | uint64

Center frequency of the bandstop FIR filter, Fc, specified as a normalized scalar in the range (0,1].

Data Types: single | double

Bandwidth of the bandstop FIR filter, BW, specified as a normalized scalar in the range (0,1].

Data Types: single | double

Window design method, specified as one of these options:

  • "hamming"

  • "hann"

  • "blackman"

  • "blackman-harris"

  • "chebyshev" –– The default sidelobe attenuation is 60 dB.

  • "kaiser"

  • "custom" –– Specify the custom window vector in the CustomWindow argument.

Data Types: char | string

Custom window vector, specified as a vector of length FilterOrder + 1.

Data Types: single | double

Option to create System object, specified as one of these:

  • false –– The function returns a vector of FIR filter coefficients.

  • true –– The function returns a dsp.FIRFilter object.

Data Types: logical

Option to print function call in MATLAB, specified as one of these:

  • false –– The function does not print the function call.

  • true –– The function prints the entire function call including the default values of the Name=Value arguments that you did not specify when calling the function.

    Use this argument to view all the values used by the function to design and implement the filter.

Data Types: logical

Output Arguments

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Bandstop FIR filter coefficients or filter object, returned as one of these:

  • Row vector –– The function returns a row vector of length FilterOrder + 1 when you set the SystemObject argument to false.

  • dsp.FIRFilter System object –– The function returns a filter object when you set the SystemObject argument to true.

Data Types: single | double

Extended Capabilities

C/C++ Code Generation
Generate C and C++ code using MATLAB® Coder™.

Version History

Introduced in R2023b

See Also

Functions

Objects

Blocks