Analyze Data

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

Functions

`bode`	Bode plot of frequency response, or magnitude and phase data
`bodemag`	Magnitude-only Bode plot of frequency response
`plot`	Plot input and output channels of `iddata` object
`advice`	Analysis and recommendations for data or estimated linear models
`delayest`	Estimate time delay (dead time) from data
`isreal`	Determine whether model parameters or data values are real
`realdata`	Determine whether `iddata` is based on real-valued signals
`feedback`	Identify possible feedback data
`pexcit`	Level of excitation of input signals
`impulseest`	Nonparametric impulse response estimation
`etfe`	Estimate empirical transfer functions and periodograms
`spa`	Estimate frequency response with fixed frequency resolution using spectral analysis
`spafdr`	Estimate frequency response and spectrum using spectral analysis with frequency-dependent resolution

iddataPlotOptions Option set for plot when plotting data contained in an iddata object

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

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

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

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

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