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Swept-frequency cosine input signal

Use a `frest.Chirp`

object to represent a swept-frequency
cosine input signal for frequency response estimation. A swept-frequency cosine input signal,
or *chirp* signal, excites your system at a range of
frequencies, such that the input frequency changes instantaneously.

Chirp signals are useful when your system is nearly linear in the simulation range. They are also useful when you want to obtain a response quickly for a lot of frequency points. The frequency-response model that results when you use a chirp input contains only frequencies that fall within the range of the chirp.

You can use a chirp input signal for estimation at the command line, in the **Model
Linearizer**, or with the Frequency Response Estimator block. The
estimation algorithm injects the signal at the input point you specify for estimation, and
measures the response at the output point. For more information, see Chirp Input Signals.

To view a plot of your input signal, type `plot(input)`

. To create a
`timeseries`

object for your input signal, use the `generateTimeseries`

command.

creates a swept-frequency cosine input signal with properties based on the dynamics of the
linear system `input`

= frest.Chirp(`sys`

)`sys`

. For instance, if you have an exact linearization
of your system, you can use it to initialize the parameters.

creates a swept-frequency cosine input signal with properties
specified using one or more name-value pairs. Enclose each property name in quotes.`input`

= frest.Chirp(`Name,Value`

)

`frestimate` | Frequency response estimation of Simulink models |

`generateTimeseries` | Generate time-domain data for input signal |

`frest.simCompare` | Plot time-domain simulation of nonlinear and linear models |

`frest.simView` | Plot frequency response model in time- and frequency-domain |

`getSimulationTime` | Final time of simulation for frequency response estimation |

In the **Model Linearizer**, to use a chirp input signal for estimation, on the
**Estimation** tab, select **Input Signal** > **Chirp**.