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Digital Filter Analysis

Magnitude, phase, impulse, and step responses, phase and group delays, pole-zero analysis

Analyze frequency- and time-domain responses of filters. Visualize filter poles and zeros in the complex plane.


absAbsolute value (magnitude)
anglePhase angle
freqzFrequency response of digital filter
grpdelayAverage filter delay (group delay)
phasedelayPhase delay of digital filter
phasezPhase response of digital filter
unwrapCorrect phase angles to produce smoother phase plots
zerophaseZero-phase response of digital filter
zplaneZero-pole plot
impzImpulse response of digital filter
impzlengthImpulse response length
stepzStep response of digital filter
filtordFilter order
filternorm 2-norm or infinity-norm of digital filter
firtypeType of linear phase FIR filter
isallpassDetermine whether filter is allpass
isfirDetermine if digital filter has finite impulse response
islinphaseDetermine whether filter has linear phase
ismaxphaseDetermine whether filter is maximum phase
isminphaseDetermine whether filter is minimum phase
isstableDetermine whether filter is stable
fvtoolOpen Filter Visualization Tool


Filter DesignerDesign filters starting with algorithm selection


Compensate for the Delay Introduced by an FIR Filter

Use indexing to counteract the time shifts introduced by filtering.

Compensate for the Delay Introduced by an IIR Filter

Remove delays and distortion introduced by filtering, when it is critical to keep phase information intact.

Take Derivatives of a Signal

Use a differentiator filter to differentiate a signal without amplifying the noise.

Speaker Crossover Filters

Devise a simple model of a digital three-way loudspeaker using Chebyshev Type I designs. Visualize the poles, zeros, and frequency responses of the filters.

Frequency Response

Compute and display frequency responses of IIR and FIR lowpass, highpass, and bandpass filters.

Phase Response

Extract the phase response of a filter.


Measure the average time delay of a filter as a function of frequency.

Zero-Pole Analysis

Find and visualize poles and zeros of a linear system.

Impulse Response

Generate and display the impulse response of a simple filter.

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