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Get 3 dB bandwidth



BW = getBandwidth(npFilter) returns the 3 dB bandwidth for the notch peak filter. If the Specification property is set to 'Quality factor and center frequency', the 3 dB bandwidth is determined from the quality factor value. If the Specification property is set to 'Coefficients', the 3 dB bandwidth is determined from the BandwidthCoefficient value and the sample rate.


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Create a dsp.NotchPeakFilter object. Set the Specification property to 'Quality factor and center frequency' and the NormalizedFrequency property to true. The default quality factor Q is 5, and the center frequency Fc is 0.5 in normalized units.

np = dsp.NotchPeakFilter(Specification='Quality factor and center frequency',...
np = 
  dsp.NotchPeakFilter with properties:

          Specification: 'Quality factor and center frequency'
          QualityFactor: 5
        CenterFrequency: 0.5000
    NormalizedFrequency: true

Compute the 3 dB bandwidth of the notch peak filter using the getBandwidth function. The function computes the bandwidth as the ratio of the center frequency and the quality factor, FcQ. Since Fc is in normalized units, the function computes the 3 dB bandwidth in normalized units.

ans = 0.1000

Visualize the filter response.


Input Arguments

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Notch peak filter whose 3 dB bandwidth is measured, specified as a dsp.NotchPeakFilter object.

Output Arguments

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3 dB bandwidth of the filter, returned as a scalar.

Data Types: double

Version History

Introduced in R2014a

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