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.

Apps

Filter Analyzer	View, analyze, and compare filters (Since R2024a)
Filter Designer	Design filters starting with algorithm selection

Functions

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Frequency-Domain Responses

`abs`	Absolute value and complex magnitude
`angle`	Phase angle
`freqz`	Frequency response of digital filter
`grpdelay`	Average filter delay (group delay)
`phasedelay`	Phase delay of digital filter
`phasez`	Phase response of digital filter
`unwrap`	Shift phase angles
`zerophase`	Zero-phase response of digital filter
`zplane`	Zero-pole plot for discrete-time systems

Time-Domain Responses

`impz`	Impulse response of digital filter
`impzlength`	Impulse response length
`stepz`	Step response of digital filter

Filter Exploration

`filterAnalyzer`	Analyze filters with Filter Analyzer app (Since R2024a)
`filtord`	Filter order
`filternorm`	2-norm or infinity-norm of digital filter
`firtype`	Type of linear phase FIR filter
`isallpass`	Determine whether filter is allpass
`isfir`	Determine if digital filter has finite impulse response
`islinphase`	Determine whether filter has linear phase
`ismaxphase`	Determine whether filter is maximum phase
`isminphase`	Determine whether filter is minimum phase
`isstable`	Determine whether filter is stable

Topics

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.
Group Delay and Phase Delay
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.
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.

Featured Examples

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.

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Take Derivatives of a Signal

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

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