Digital Filtering

Zero-phase filtering, median filtering, overlap-add filtering, transfer function representation

Lowpass, highpass, bandpass, and bandstop filter multichannel data without having to design filters or compensate for delays. Perform zero-phase filtering to remove delay and phase distortion. Use median or Hampel filtering to remove spikes and outliers. Convert transfer functions to different representations, such as second-order sections or poles and zeros.

Apps

Signal Analyzer

Visualize and compare multiple signals and spectra

Functions

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Filtering Functions

`bandpass`	Bandpass-filter signals
`bandstop`	Bandstop-filter signals
`highpass`	Highpass-filter signals
`lowpass`	Lowpass-filter signals
`ctffilt`	Cascaded transfer function filtering (Since R2024b)
`fftfilt`	FFT-based FIR filtering using overlap-add method
`filter`	1-D digital filter
`filter2`	2-D digital filter
`filtfilt`	Zero-phase digital filtering
`filtic`	Initial conditions for transposed direct-form II filter implementation
`hampel`	Outlier removal using Hampel identifier
`latcfilt`	Lattice and lattice-ladder filter implementation
`medfilt1`	1-D median filtering
`residuez`	Z-transform partial-fraction expansion
`sgolayfilt`	Savitzky-Golay filtering
`sosfilt`	Second-order (biquadratic) IIR digital filtering

Convolution

`conv`	Convolution and polynomial multiplication
`conv2`	2-D convolution
`convmtx`	Convolution matrix
`deconv`	Least-squares deconvolution and polynomial division

Linear System Transformations

`cell2sos`	Convert second-order sections cell array to matrix
`eqtflength`	Equalize lengths of transfer function numerator and denominator
`latc2tf`	Convert lattice filter coefficients to transfer function form
`scaleFilterSections`	Scale cascaded transfer functions with scale values (Since R2023b)
`sos2ctf`	Convert digital filter second-order section parameters to cascaded transfer function form (Since R2024a)
`sos2cell`	Convert second-order sections matrix to cell array
`sos2ss`	Convert digital filter second-order section parameters to state-space form
`sos2tf`	Convert digital filter second-order section data to transfer function form
`sos2zp`	Convert digital filter second-order section parameters to zero-pole-gain form
`ss`	Convert digital filter to state-space representation
`ss2sos`	Convert digital filter state-space parameters to second-order sections form
`ss2tf`	Convert state-space representation to transfer function
`ss2zp`	Convert state-space filter parameters to zero-pole-gain form
`tf`	Convert digital filter to transfer function
`tf2latc`	Convert transfer function filter coefficients to lattice filter form
`tf2sos`	Convert digital filter transfer function data to second-order sections form
`tf2ss`	Convert transfer function filter parameters to state-space form
`tf2zp`	Convert transfer function filter parameters to zero-pole-gain form
`tf2zpk`	Convert transfer function filter parameters to zero-pole-gain form
`zp2ctf`	Convert zero-pole-gain filter parameters to cascaded transfer function form (Since R2024a)
`ctf2zp`	Convert cascaded transfer functions to zero-pole-gain form (Since R2024b)
`zp2sos`	Convert zero-pole-gain filter parameters to second-order sections form
`zp2ss`	Convert zero-pole-gain filter parameters to state-space form
`zp2tf`	Convert zero-pole-gain filter parameters to transfer function form
`zpk`	Convert digital filter to zero-pole-gain representation

Simulink Interaction

`dspfwiz`	Create Simulink filter block using Realize Model panel
`filt2block`	Generate Simulink filter block

Topics

Filtering Data with Signal Processing Toolbox Software
Design and implement a filter using command-line functions or an interactive app.
Anti-Causal, Zero-Phase Filter Implementation
Eliminate the phase distortion introduced by an IIR 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.
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.
Discrete-Time System Models
Explore different schemes to represent digital filters.
Linear System Transformations
Convert between various representational schemes for digital filters.
Human Activity Recognition Simulink Model for Smartphone Deployment (Statistics and Machine Learning Toolbox)
Generate code from a classification Simulink^® model prepared for deployment to a smartphone.

Featured Examples

Practical Introduction to Digital Filtering

Design, analyze, and apply digital filters to remove unwanted content from a signal without distorting the data.

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Extract Voices from Music Signal

Use Signal Analyzer to extract voices from a song by duplicating and filtering signals.

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Resample and Filter a Nonuniformly Sampled Signal

Use Signal Analyzer to resample and filter a signal with missing data.

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