Digital Filter Design

FIR, IIR, windowing, equiripple, least squares, Butterworth, Chebyshev, elliptic, pulse shaping

Design digital filters using as a starting point a set of specifications (designfilt) or a design algorithm (butter, fir1). Generate FIR differentiators and Hilbert filters.

Apps

Filter Designer

Design filters starting with algorithm selection

Functions

expand all

IIR Filters

`butter`	Butterworth filter design
`buttord`	Butterworth filter order and cutoff frequency
`cheby1`	Chebyshev Type I filter design
`cheb1ord`	Chebyshev Type I filter order
`cheby2`	Chebyshev Type II filter design
`cheb2ord`	Chebyshev Type II filter order
`designfilt`	Design digital filters
`ellip`	Elliptic filter design
`ellipord`	Minimum order for elliptic filters
`polyscale`	Scale roots of polynomial
`polystab`	Stabilize polynomial
`yulewalk`	Recursive digital filter design

FIR Filters

`cfirpm`	Complex and nonlinear-phase equiripple FIR filter design
`designfilt`	Design digital filters
`fir1`	Window-based FIR filter design
`fir2`	Frequency sampling-based FIR filter design
`fircls`	Constrained-least-squares FIR multiband filter design
`fircls1`	Constrained-least-squares linear-phase FIR lowpass and highpass filter design
`firls`	Least-squares linear-phase FIR filter design
`firpm`	Parks-McClellan optimal FIR filter design
`firpmord`	Parks-McClellan optimal FIR filter order estimation
`gaussdesign`	Gaussian FIR pulse-shaping filter design
`intfilt`	Interpolation FIR filter design
`kaiserord`	Kaiser window FIR filter design estimation parameters
`maxflat`	Generalized digital Butterworth filter design
`rcosdesign`	Raised cosine FIR pulse-shaping filter design
`sgolay`	Savitzky-Golay filter design

Filter Utilities

`digitalFilter`	Digital filter
`double`	Cast coefficients of digital filter to double precision
`dspfwiz`	Create Simulink filter block using Realize Model panel
`filt2block`	Generate Simulink filter block
`info`	Information about digital filter
`isdouble`	Determine if digital filter coefficients are double precision
`issingle`	Determine if digital filter coefficients are single precision
`single`	Cast coefficients of digital filter to single precision

Filter Visualization Tool

FVTool

Filter Visualization Tool

Topics

IIR Filter Design

Compare classical Butterworth, Chebyshev, and elliptic designs. Explore Bessel, Yule-Walker, and generalized Butterworth filters.

FIR Filter Design

Use windowing, least squares, or the Parks-McClellan algorithm to design lowpass, highpass, multiband, or arbitrary-response filters, differentiators, or Hilbert transformers.

Filter Implementation

Filter signals using the filter function.

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.

Take Derivatives of a Signal

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

Filter Builder Design Process

filterBuilder is a graphical interface that speeds up the filter design process.