Signal Processing Toolbox™

Function Reference

Digital Filters

FIR Filter Design	Design functions for FIR filters
Communications Filters	Design functions used in communications
IIR Digital Filter Design	Design functions for IIR filters
IIR Filter Order Estimation	Estimation functions for IIR filters
Filter Analysis	Functions for analyzing filters
Filter Implementation	Functions for implementing filters

FIR Filter Design

cfirpm	Complex and nonlinear-phase equiripple FIR filter design
fir1	Window-based finite impulse response filter design
fir2	Frequency sampling-based finite impulse response filter design
fircls	Constrained least square, FIR multiband filter design
fircls1	Constrained least square, lowpass and highpass, linear phase, FIR filter design
firls	Least square linear-phase FIR filter design
firpm	Parks-McClellan optimal FIR filter design
firpmord	Parks-McClellan optimal FIR filter order estimation
intfilt	Interpolation FIR filter design
kaiserord	Kaiser window FIR filter design estimation parameters
sgolay	Savitzky-Golay filter design

Communications Filters

firrcos	Raised cosine FIR filter design
gaussfir	Gaussian FIR pulse-shaping filter

IIR Digital Filter Design

butter	Butterworth analog and digital filter design
cheby1	Chebyshev Type I filter design (passband ripple)
cheby2	Chebyshev Type II filter design (stopband ripple)
ellip	Elliptic (Cauer) filter design
maxflat	Generalized digital Butterworth filter design
yulewalk	Recursive digital filter design

IIR Filter Order Estimation

buttord	Butterworth filter order and cutoff frequency
cheb1ord	Chebyshev Type I filter order
cheb2ord	Chebyshev Type II filter order
ellipord	Minimum order for elliptic filters

Filter Analysis

abs	Absolute value (magnitude)
angle	Phase angle
filternorm	2-norm or infinity-norm of digital filter
freqz	Frequency response of digital filter
fvtool	Open Filter Visualization Tool
grpdelay	Average filter delay (group delay)
impz	Impulse response of digital filter
phasedelay	Phase delay of digital filter
phasez	Phase response of digital filter
stepz	Step response of digital filter
unwrap	Unwrap phase angles
zerophase	Zero-phase response of digital filter
zplane	Zero-pole plot

Filter Implementation

cconv	Modulo-N circular convolution
conv	Convolution and polynomial multiplication
conv2	Two-dimensional convolution
convmtx	Convolution matrix
deconv	Deconvolution and polynomial division
fftfilt	FFT-based FIR filtering using overlap-add method
filter	Filter data with recursive (IIR) or nonrecursive (FIR) filter
filter2	Two-dimensional digital filtering
filtfilt	Zero-phase digital filtering
filtic	Iinitial conditions for transposed direct-form II filter implementation
latcfilt	Lattice and lattice-ladder filter implementation
medfilt1	1-D median filtering
sgolayfilt	Savitzky-Golay filtering
sosfilt	Second-order (biquadratic) IIR digital filtering
upfirdn	Upsample, apply FIR filter, and downsample

Analog Filters

Analog Lowpass Filter Prototypes	Prototyping functions for analog lowpass filters
Analog Filter Design	Design functions for analog filters
Filter Analysis	Analysis functions for analog filters
Analog Filter Transformation	Transformation functions for analog filters
Filter Discretization	Discretization functions for analog filters

Analog Lowpass Filter Prototypes

besselap	Bessel analog lowpass filter prototype
buttap	Butterworth analog lowpass filter prototype
cheb1ap	Chebyshev Type I analog lowpass filter prototype
cheb2ap	Chebyshev Type II analog lowpass filter prototype
ellipap	Elliptic analog lowpass filter prototype

Analog Filter Design

besself	Bessel analog filter design
butter	Butterworth analog and digital filter design
cheby1	Chebyshev Type I filter design (passband ripple)
cheby2	Chebyshev Type II filter design (stopband ripple)
ellip	Elliptic (Cauer) filter design

Filter Analysis

abs	Absolute value (magnitude)
freqs	Frequency response of analog filters
freqspace	Frequency spacing for frequency response

Analog Filter Transformation

lp2bp	Transform lowpass analog filters to bandpass
lp2bs	Transform lowpass analog filters to bandstop
lp2hp	Transform lowpass analog filters to highpass
lp2lp	Change cutoff frequency for lowpass analog filter

Filter Discretization

bilinear	Bilinear transformation method for analog-to-digital filter conversion
impinvar	Impulse invariance method for analog-to-digital filter conversion

Linear Systems

latc2tf	Convert lattice filter parameters to transfer function form
polyscale	Scale roots of polynomial
polystab	Stabilize polynomial
residuez	z-transform partial-fraction expansion
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
ss2sos	Convert digital filter state-space parameters to second-order sections form
ss2tf	Convert state-space filter parameters to transfer function form
ss2zp	Convert state-space filter parameters to zero-pole-gain form
tf2latc	Convert transfer function filter parameters 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
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

Windows

barthannwin	Modified Bartlett-Hann window
bartlett	Bartlett window
blackman	Blackman window
blackmanharris	Minimum 4-term Blackman-Harris window
bohmanwin	Bohman window
chebwin	Chebyshev window
dpss	Discrete prolate spheroidal sequences (Slepian sequences)
dpssclear	Remove discrete prolate spheroidal sequences from database
dpssdir	Discrete prolate spheroidal sequences database directory
dpssload	Load discrete prolate spheroidal sequences from database
dpsssave	Save discrete prolate spheroidal sequences in database
flattopwin	Flat Top weighted window
gausswin	Gaussian window
hamming	Hamming window
hann	Hann (Hanning) window
kaiser	Kaiser window
nuttallwin	Nuttall-defined minimum 4-term Blackman-Harris window
parzenwin	Parzen (de la Valle-Poussin) window
rectwin	Rectangular window
taylorwin	Taylor window
triang	Triangular window
tukeywin	Tukey (tapered cosine) window
window	Window function gateway
wvtool	Open Window Visualization Tool

Transforms

bitrevorder	Permute data into bit-reversed order
czt	Chirp z-transform
dct	Discrete cosine transform (DCT)
dftmtx	Discrete Fourier transform matrix
digitrevorder	Permute input into digit-reversed order
fft	1–D fast Fourier transform
fft2	2–D fast Fourier transform
fftshift	Rearrange FFT function outputs
goertzel	Discrete Fourier transform using second-order Goertzel algorithm
hilbert	Discrete-time analytic signal using Hilbert transform
idct	Inverse discrete cosine transform
ifft	1-D inverse fast Fourier transform
ifft2	2-D inverse fast Fourier transform

Cepstral Analysis

cceps	Complex cepstral analysis
icceps	Inverse complex cepstrum
rceps	Real cepstrum and minimum phase reconstruction

Statistical Signal Processing

corrcoef	Correlation coefficient matrix
corrmtx	Data matrix for autocorrelation matrix estimation
cov	Covariance matrix
cpsd	Cross power spectral density
dspdata	DSP data parameter information
mscohere	Magnitude squared coherence
pburg	PSD using Burg method
pcov	PSD using covariance method
peig	Pseudospectrum using eigenvector method
periodogram	PSD using periodogram
pmcov	PSD using modified covariance method
pmtm	PSD using multitaper method (MTM)
pmusic	Pseudospectrum using MUSIC algorithm
pwelch	PSD using Welch's method
pyulear	PSD using Yule-Walker AR method
rooteig	Frequency and power content using eigenvector method
rootmusic	Frequency and power content using root MUSIC algorithm
spectrogram	Spectrogram using short-time Fourier transform
spectrum	Spectral estimation
tfestimate	Transfer function estimate
xcorr	Cross-correlation
xcorr2	2–D cross-correlation
xcov	Cross-covariance

Parametric Modeling

arburg	Estimate AR model parameters using Burg method
arcov	Estimate AR model parameters using covariance method
armcov	Estimate AR model parameters using modified covariance method
aryule	Estimate AR model parameters using Yule-Walker method
invfreqs	Identify continuous-time filter parameters from frequency response data
invfreqz	Identify discrete-time filter parameters from frequency response data
prony	Prony's method for time domain IIR filter design
stmcb	Compute linear model using Steiglitz-McBride iteration

Linear Prediction

ac2poly	Convert autocorrelation sequence to prediction polynomial
ac2rc	Convert autocorrelation sequence to reflection coefficients
is2rc	Convert inverse sine parameters to reflection coefficients
lar2rc	Convert log area ratio parameters to reflection coefficients
levinson	Levinson-Durbin recursion
lpc	Linear prediction filter coefficients
lsf2poly	Convert line spectral frequencies to prediction filter coefficients
poly2ac	Convert prediction filter polynomial to autocorrelation sequence
poly2lsf	Convert prediction filter coefficients to line spectral frequencies
poly2rc	Convert prediction filter polynomial to reflection coefficients
rc2ac	Convert reflection coefficients to autocorrelation sequence
rc2is	Convert reflection coefficients to inverse sine parameters
rc2lar	Convert reflection coefficients to log area ratio parameters
rc2poly	Convert reflection coefficients to prediction filter polynomial
rlevinson	Reverse Levinson-Durbin recursion
schurrc	Compute reflection coefficients from autocorrelation sequence

Multirate Signal Processing

decimate	Decimation — decrease sampling rate
downsample	Decrease sampling rate by integer factor
interp	Interpolation — increase sampling rate by integer factor
resample	Change sampling rate by rational factor
upfirdn	Upsample, apply FIR filter, and downsample
upsample	Increase sampling rate by integer factor

Waveform Generation

chirp	Swept-frequency cosine
diric	Dirichlet or periodic sinc function
gauspuls	Gaussian-modulated sinusoidal pulse
gmonopuls	Gaussian monopulse
pulstran	Pulse train
rectpuls	Sampled aperiodic rectangle
sawtooth	Sawtooth or triangle wave
sinc	Sinc
square	Square wave
tripuls	Sampled aperiodic triangle
vco	Voltage controlled oscillator

Specialized Operations

buffer	Buffer signal vector into matrix of data frames
cell2sos	Convert second-order sections cell array to matrix
cplxpair	Group complex numbers into complex conjugate pairs
db2mag	Convert decibels (dB) to magnitude
db2pow	Convert decibels (dB) to power
demod	Demodulation for communications simulation
eqtflength	Equalize lengths of transfer function's numerator and denominator
findpeaks	Find local maxima
mag2db	Convert magnitude to decibels (dB)
marcumq	Generalized Marcum Q function
modulate	Modulation for communications simulation
pow2db	Convert power to decibels (dB)
seqperiod	Compute period of sequence
sos2cell	Convert second-order sections matrix to cell array
strips	Strip plot
udecode	Decode 2ⁿ-level quantized integer inputs to floating-point outputs
uencode	Quantize and encode floating-point inputs to integer outputs

Graphical User Interfaces

fdatool	Open Filter Design and Analysis Tool
fvtool	Open Filter Visualization Tool
sptool	Open interactive digital signal processing tool
wintool	Open Window Design and Analysis Tool
wvtool	Open Window Visualization Tool

Using the Filter Designer

Functions — Alphabetical List