Main Content

Analyze Data

Determine data characteristics such as delay, feedback, and excitation level


bodeBode plot of frequency response, or magnitude and phase data
bodemag Magnitude-only Bode plot of frequency response
plotPlot input and output channels of iddata object
adviceAnalysis and recommendations for data or estimated linear models
delayestEstimate time delay (dead time) from data
isrealDetermine whether model parameters or data values are real
realdataDetermine whether iddata is based on real-valued signals
feedbackIdentify possible feedback data
pexcitLevel of excitation of input signals
impulseestNonparametric impulse response estimation
etfeEstimate empirical transfer functions and periodograms
spaEstimate frequency response with fixed frequency resolution using spectral analysis
spafdrEstimate frequency response and spectrum using spectral analysis with frequency-dependent resolution
iddataPlotOptionsOption set for plot when plotting data contained in an iddata object

Examples and How To

How to Plot Data in the App

After importing data into the System Identification app, as described in Represent Data, you can plot the data.

How to Plot Data at the Command Line

The following table summarizes the commands available for plotting time-domain, frequency-domain, and frequency-response data.

How to Analyze Data Using the advice Command

You can use the advice command to analyze time- or frequency- domain data before estimating a model.

Identify Delay Using Transient-Response Plots

You can use transient-response plots to estimate the input delay, or dead time, of linear systems.


Is Your Data Ready for Modeling?

Before you start estimating models from data, you should check your data for the presence of any undesirable characteristics.