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visualizeFilterStages

Display response of digital down converter or digital up converter filter cascade

Description

visualizeFilterStages(Conv) plots the magnitude response of the filter stages and the cascade response of a digital down converter or digital up converter, Conv. The function plots the response of the filters up to the second CIC null frequency (or to the first when only one CIC null exists).

example

visualizeFilterStages(Conv,'Arithmetic',arithType) specifies the arithmetic type of the filter stages. Set input arithType to 'double', 'single', or 'fixed-point'. When the Conv object is in an unlocked state, you must specify the arithmetic type. When the Conv object is in a locked state, the object ignores the arithmetic input argument.

fvt = visualizeFilterStages(Conv) returns the handle to the FVTool object.

Examples

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Plot the magnitude response of the digital down converter using the fvtool function and the visualizeFilterStages function.

Create a dsp.DigitalDownConverter System object with the default settings. Using the fvtool function, plot the magnitude response of the overall filter cascade. The visualizeFilterStages function in addition plots the magnitude response of the individual filters stages.

dwnConv = dsp.DigitalDownConverter
dwnConv = 
  dsp.DigitalDownConverter with properties:

           DecimationFactor: 100
         MinimumOrderDesign: true
                  Bandwidth: 200000
    StopbandFrequencySource: 'Auto'
             PassbandRipple: 0.1000
        StopbandAttenuation: 60
                 Oscillator: 'Sine wave'
            CenterFrequency: 14000000
                 SampleRate: 30000000

  Use get to show all properties

Using fvtool

If the System object is unlocked, you must specify the filter arithmetic through the 'Arithmetic' input of the fvtool function. If the System object is locked, the arithmetic input is ignored.

fvtool(dwnConv,'Arithmetic','fixed-point')

Figure Figure 1: Magnitude Response (dB) contains an axes object. The axes object with title Magnitude Response (dB), xlabel Frequency (MHz), ylabel Magnitude (dB) contains 3 objects of type line. These objects represent Filter #1: Quantized, Filter #1: Reference.

Using visualizeFilterStages

To view the magnitude response of the individual filter stages, call the visualizeFilterStages function.

visualizeFilterStages(dwnConv,'Arithmetic','fixed-point')

Figure Figure 2: Magnitude Response (dB) contains an axes object. The axes object with title Magnitude Response (dB), xlabel Frequency (MHz), ylabel Magnitude (dB) contains 9 objects of type line. These objects represent CIC decimator, Decimation factor = 25: Quantized, CIC decimator, Decimation factor = 25: Reference, CIC compensator, Decimation factor = 2: Quantized, CIC compensator, Decimation factor = 2: Reference, Halfband decimator, Decimation factor = 2: Quantized, Halfband decimator, Decimation factor = 2: Reference, Cascade response: Quantized, Cascade response: Reference.

Input Arguments

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Digital down converter or digital up converter, specified as a dsp.DigitalDownConverter or dsp.DigitalUpConverter System object™.

Arithmetic type of the filter stages, specified as 'double', 'single', or 'fixed-point'. When the Conv object is in an unlocked state, you must specify the arithmetic type. When the Conv object is in a locked state, the object ignores the arithmetic input argument.

Version History

Introduced in R2012a