目录 Signal Processing Toolbox Functions - By Category Signal Generation and Preprocessing Smoothing and Denoising Waveform Generation Resampling Measurements and Feature Extraction Descriptive Statistics Pulse and Transition Metrics Spectral Measurements Correlation and Convolution Digital and Analog Filters Digital Filter Design Digital Filter Analysis Digital Filtering Multirate Signal Processing Analog Filters Transforms Spectral Analysis Spectral Estimation Parametric Spectral Estimation Subspace Methods Windows Spectral Measurements Time-Frequency Analysis Signal Modeling Autoregressive and Moving Average Models Linear Predictive Coding Vibration Analysis

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Signal Processing Toolbox Functions - By Category

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Signal Generation and Preprocessing

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Smoothing and Denoising

detrend Remove linear trends filloutliers Detect and replace outliers in data hampel Outlier removal using Hampel identifier isoutlier Find outliers in data medfilt1 1-D median filtering movmad Moving median absolute deviation movmedian Moving median sgolay Savitzky-Golay filter design sgolayfilt Savitzky-Golay filtering smoothdata Smooth noisy data

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Waveform Generation

chirp Swept-frequency cosine diric Dirichlet or periodic sinc function gauspuls Gaussian-modulated sinusoidal pulse gmonopuls Gaussian monopulse pulstran Pulse train randn Normally distributed random numbers rectpuls Sampled aperiodic rectangle sawtooth Sawtooth or triangle wave sin Sine of argument in radians sinc Sinc function square Square wave stem Plot discrete sequence data tripuls Sampled aperiodic triangle vco Voltage controlled oscillator buffer Buffer signal vector into matrix of data frames demod Demodulation for communications simulation modulate Modulation for communications simulation seqperiod Compute period of sequence shiftdata Shift data to operate on specified dimension unshiftdata Inverse of shiftdata strips Strip plot udecode Decode 2n-level quantized integer inputs to floating-point outputs uencode Quantize and encode floating-point inputs to integer outputs marcumq Generalized Marcum Q function

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Resampling

decimate Decimation — decrease sample rate by integer factor downsample Decrease sample rate by integer factor fillgaps Fill gaps using autoregressive modeling fillmissing Fill missing values interp Interpolation — increase sample rate by integer factor interp1 1-D data interpolation (table lookup) pchip Piecewise Cubic Hermite Interpolating Polynomial (PCHIP) resample Resample uniform or nonuniform data to new fixed rate spline Cubic spline data interpolation upfirdn Upsample, apply FIR filter, and downsample upsample Increase sample rate by integer factor

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Measurements and Feature Extraction

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Descriptive Statistics

cummax Cumulative maximum cummin Cumulative minimum envelope Signal envelope max Maximum elements of an array mean Average or mean value of array meanfreq Mean frequency medfreq Median frequency median Median value of array min Minimum elements of an array movmad Moving median absolute deviation movmedian Moving median peak2peak Maximum-to-minimum difference peak2rms Peak-magnitude-to-RMS ratio rms Root-mean-square level rssq Root-sum-of-squares level seqperiod Compute period of sequence std Standard deviation var Variance alignsignals Align two signals by delaying earliest signal cusum Detect small changes in mean using cumulative sum dtw Distance between signals using dynamic time warping edr Edit distance on real signals findchangepts Find abrupt changes in signal finddelay Estimate delay(s) between signals findpeaks Find local maxima findsignal Find signal location using similarity search

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Pulse and Transition Metrics

dutycycle Duty cycle of pulse waveform midcross Mid-reference level crossing for bilevel waveform pulseperiod Period of bilevel pulse pulsesep Separation between bilevel waveform pulses pulsewidth Bilevel waveform pulse width statelevels State-level estimation for bilevel waveform with histogram method falltime Fall time of negative-going bilevel waveform transitions overshoot Overshoot metrics of bilevel waveform transitions risetime Rise time of positive-going bilevel waveform transitions settlingtime Settling time for bilevel waveform slewrate Slew rate of bilevel waveform undershoot Undershoot metrics of bilevel waveform transitions

Spectral Measurements

bandpower Band power enbw Equivalent noise bandwidth instfreq Estimate instantaneous frequency meanfreq Mean frequency medfreq Median frequency obw Occupied bandwidth pentropy Spectral entropy of signal pkurtosis Spectral kurtosis from signal or spectrogram powerbw Power bandwidth sfdr Spurious free dynamic range sinad Signal to noise and distortion ratio snr Signal-to-noise ratio thd Total harmonic distortion toi Third-order intercept point

Correlation and Convolution

corrcoef Correlation coefficients corrmtx Data matrix for autocorrelation matrix estimation xcorr Cross-correlation xcorr2 2-D cross-correlation xcov Cross-covariance cconv Modulo-N circular convolution conv Convolution and polynomial multiplication conv2 2-D convolution convmtx Convolution matrix cov Covariance deconv Deconvolution and polynomial division alignsignals Align two signals by delaying earliest signal dtw Distance between signals using dynamic time warping edr Edit distance on real signals finddelay Estimate delay(s) between signals findsignal Find signal location using similarity search

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Digital and Analog Filters

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Digital Filter Design

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 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 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 fvtool Open Filter Visualization Tool 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

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Digital Filter Analysis

abs Absolute value or 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 Correct phase angles to produce smoother phase plots zerophase Zero-phase response of digital filter zplane Zero-pole plot for discrete-time systems impz Impulse response of digital filter impzlength Impulse response length stepz Step response of digital filter 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 fvtool Open Filter Visualization Tool

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Digital Filtering

bandpass Bandpass-filter signals bandstop Bandstop-filter signals highpass Highpass-filter signals lowpass Lowpass-filter signals fftfilt FFT-based FIR filtering using overlap-add method filter Filter data with recursive (IIR) or nonrecursive (FIR) 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 conv Convolution and polynomial multiplication conv2 2-D convolution convmtx Convolution matrix deconv Deconvolution and polynomial division cell2sos Convert second-order sections cell array to matrix eqtflength Equalize lengths of transfer function's numerator and denominator latc2tf Convert lattice filter parameters to transfer function form 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 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 zpk Convert digital filter to zero-pole-gain representation dspfwiz Create Simulink filter block using Realize Model panel filt2block Generate Simulink filter block

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Multirate Signal Processing

decimate Decimation — decrease sample rate by integer factor downsample Decrease sample rate by integer factor fillgaps Fill gaps using autoregressive modeling interp Interpolation — increase sample rate by integer factor interp1 1-D data interpolation (table lookup) pchip Piecewise Cubic Hermite Interpolating Polynomial (PCHIP) resample Resample uniform or nonuniform data to new fixed rate spline Cubic spline data interpolation upfirdn Upsample, apply FIR filter, and downsample upsample Increase sample rate by integer factor

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Analog Filters

besself Bessel analog filter design butter Butterworth filter design cheby1 Chebyshev Type I filter design cheby2 Chebyshev Type II filter design ellip Elliptic filter design freqs Frequency response of analog filters freqspace Frequency spacing for frequency response besselap Bessel analog lowpass filter prototype bilinear Bilinear transformation method for analog-to-digital filter conversion buttap Butterworth filter prototype cheb1ap Chebyshev Type I analog lowpass filter prototype cheb2ap Chebyshev Type II analog lowpass filter prototype ellipap Elliptic analog lowpass filter prototype impinvar Impulse invariance method for analog-to-digital filter conversion 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

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Transforms

abs Absolute value or complex magnitude angle Phase angle fft Fast Fourier transform ifft Inverse fast Fourier transform fftshift Shift zero-frequency component to center of spectrum dftmtx Discrete Fourier transform matrix fft2 2-D fast Fourier transform ifft2 2-D inverse fast Fourier transform instfreq Estimate instantaneous frequency czt Chirp Z-transform goertzel Discrete Fourier transform with second-order Goertzel algorithm dct Discrete cosine transform idct Inverse discrete cosine transform envelope Signal envelope fwht Fast Walsh-Hadamard transform ifwht Inverse Fast Walsh-Hadamard transform hilbert Discrete-time analytic signal using Hilbert transform cceps Complex cepstral analysis icceps Inverse complex cepstrum rceps Real cepstrum and minimum phase reconstruction bitrevorder Permute data into bit-reversed order digitrevorder Permute input into digit-reversed order

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Spectral Analysis

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Spectral Estimation

cpsd Cross power spectral density findpeaks Find local maxima mscohere Magnitude-squared coherence pentropy Spectral entropy of signal periodogram Periodogram power spectral density estimate plomb Lomb-Scargle periodogram pmtm Multitaper power spectral density estimate poctave Generate octave spectrum pspectrum Analyze signals in the frequency and time-frequency domains pwelch Welch’s power spectral density estimate tfestimate Transfer function estimate db Convert energy or power measurements to decibels db2mag Convert decibels to magnitude db2pow Convert decibels to power mag2db Convert magnitude to decibels pow2db Convert power to decibels

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Parametric Spectral Estimation

findpeaks Find local maxima pburg Autoregressive power spectral density estimate — Burg’s method pcov Autoregressive power spectral density estimate — covariance method pmcov Autoregressive power spectral density estimate — modified covariance method pyulear Autoregressive power spectral density estimate — Yule-Walker method db Convert energy or power measurements to decibels db2mag Convert decibels to magnitude db2pow Convert decibels to power mag2db Convert magnitude to decibels pow2db Convert power to decibels

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Subspace Methods

peig Pseudospectrum using eigenvector method pmusic Pseudospectrum using MUSIC algorithm rooteig Frequency and power content using eigenvector method rootmusic Root MUSIC algorithm

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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 enbw Equivalent noise bandwidth 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 Vallée Poussin) window rectwin Rectangular window taylorwin Taylor window triang Triangular window tukeywin Tukey (tapered cosine) window wvtool Open Window Visualization Tool dpss Discrete prolate spheroidal (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 Discrete prolate spheroidal or Slepian sequence database

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Spectral Measurements

bandpower Band power enbw Equivalent noise bandwidth instfreq Estimate instantaneous frequency meanfreq Mean frequency medfreq Median frequency obw Occupied bandwidth pentropy Spectral entropy of signal pkurtosis Spectral kurtosis from signal or spectrogram powerbw Power bandwidth sfdr Spurious free dynamic range sinad Signal to noise and distortion ratio snr Signal-to-noise ratio thd Total harmonic distortion toi Third-order intercept point

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Time-Frequency Analysis

emd Empirical mode decomposition fsst Fourier synchrosqueezed transform hht Hilbert-Huang transform ifsst Inverse Fourier synchrosqueezed transform instfreq Estimate instantaneous frequency kurtogram Visualize spectral kurtosis pentropy Spectral entropy of signal pkurtosis Spectral kurtosis from signal or spectrogram pspectrum Analyze signals in the frequency and time-frequency domains spectrogram Spectrogram using short-time Fourier transform tfridge Time-frequency ridges xspectrogram Cross-spectrogram using short-time Fourier transforms

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Signal Modeling

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Autoregressive and Moving Average Models

arburg Autoregressive all-pole model parameters — Burg’s method arcov Autoregressive all-pole model parameters — covariance method armcov Autoregressive all-pole model parameters — modified covariance method aryule Autoregressive all-pole model parameters — 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 method for filter design stmcb Compute linear model using Steiglitz-McBride iteration

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Linear Predictive Coding

corrmtx Data matrix for autocorrelation matrix estimation levinson Levinson-Durbin recursion lpc Linear prediction filter coefficients rlevinson Reverse Levinson-Durbin recursion schurrc Compute reflection coefficients from autocorrelation sequence xcorr Cross-correlation xcov Cross-covariance 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 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

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Vibration Analysis

envspectrum Envelope spectrum for machinery diagnosis orderspectrum Average spectrum versus order for vibration signal ordertrack Track and extract order magnitudes from vibration signal orderwaveform Extract time-domain order waveforms from vibration signal rpmfreqmap Frequency-RPM map for order analysis rpmordermap Order-RPM map for order analysis rpmtrack Track and extract RPM profile from vibration signal tachorpm Extract RPM signal from tachometer pulses tsa Time-synchronous signal average modalfit Modal parameters from frequency-response functions modalfrf Frequency-response functions for modal analysis modalsd Generate stabilization diagram for modal analysis rainflow Rainflow counts for fatigue analysis

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