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Spectral Estimation

Periodogram, Welch, and Lomb-Scargle PSD estimates, time-frequency analysis, spectrogram, coherence, transfer function estimation, order analysis

Analyze the spectral content of uniformly or nonuniformly sampled signals using periodogram, pwelch, or plomb. Determine frequency-domain coherence between signals. Estimate transfer functions based on input and output measurements. Obtain sharp time-frequency spectral estimates using reassignment or synchrosqueezing. Use order analysis to study vibrations in rotational machinery.

Functions

cpsd Cross power spectral density
findpeaks Find local maxima
mscohere Magnitude-squared coherence
periodogram Periodogram power spectral density estimate
plomb Lomb-Scargle periodogram
pmtm Multitaper power spectral density estimate
pwelch Welch's power spectral density estimate
tfestimate Transfer function estimate
fsst Fourier synchrosqueezed transform
ifsst Inverse Fourier synchrosqueezed transform
spectrogram Spectrogram using short-time Fourier transform
tfridge Time-frequency ridges
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
tachorpm Extract RPM signal from tachometer pulses
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
sptool Open interactive digital signal processing tool

Apps

Signal Analyzer Visualize and compare multiple signals and spectra

Topics

Power Spectral Density Estimates Using FFT

Obtain nonparametric PSD estimates equivalent to the periodogram using the FFT directly.

Nonparametric Methods

Learn about the periodogram, modified periodogram, Welch, and multitaper methods of nonparametric spectral estimation.

Amplitude Estimation and Zero Padding

Obtain an accurate estimate of the amplitude of a sinusoidal signal using zero padding.

Bias and Variability in the Periodogram

Reduce bias and variability in the periodogram using windows and averaging.

Frequency-Domain Linear Regression

Construct a linear regression model for a time series using the discrete Fourier transform.

Compare the Frequency Content of Two Signals

Identify similarity between signals in the frequency domain.

Significance Testing for Periodic Component

Assess the significance of a sinusoidal component in white noise using Fisher's g-statistic.

Cross Spectrum and Magnitude-Squared Coherence

Obtain the phase lag between sinusoidal components and identify frequency-domain correlation in a time series.

FFT-Based Time-Frequency Analysis

Display the spectrogram of a linear FM signal.

Instantaneous Frequency of Sinusoids

Compute the instantaneous frequency of two sinusoids using the Fourier synchrosqueezed transform. Determine how separated the sinusoids must be for the transform to resolve them.

Nonparametric Spectrum Object to Function Replacement

Replace calls to nonparametric psd and msspectrum objects with function calls.

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