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Offline Frequency Response Estimation

Estimate frequency response, examine frequency-domain characteristics, validate linearization of Simulink® model

Simulink Control Design™ software has both command-line tools and a graphical Model Linearizer app for estimating the frequency response of a system modeled in Simulink, without modifying the model. You can use the estimated response to validate exact linearization results, analyze linear model dynamics, or estimate parametric models. For more information about frequency response estimation, see Frequency Response Estimation Basics.

Frequency response estimation requires an input signal at the linearization input point to excite the model at the frequencies of interest. For more information, see Estimation Input Signals.

Graphical Tools

Model LinearizerLinearize Simulink models
Linearization ManagerManage linear analysis points and block linearizations


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frestimateFrequency response estimation of Simulink models
frestimateOptionsOptions for frequency response estimation

Input Signals

frest.SinestreamInput signal containing series of sine waves
frest.createFixedTsSinestreamSinestream input signal with fixed sample time
frest.ChirpSwept-frequency cosine input signal
frest.PRBSPseudorandom binary sequence input signal (Since R2020a)
frest.RandomRandom input signal
frest.createStepCreate step input signal
frest.simComparePlot time-domain simulation of nonlinear and linear models
frest.simViewPlot frequency response model in time- and frequency-domain
getSimulationTimeFinal time of simulation for frequency response estimation
frest.findSourcesIdentify time-varying source blocks
frest.findDependList of model path dependencies


PRBS Signal GeneratorGenerate PRBS input signal for plant frequency response estimation (Since R2024a)
Sinestream Signal GeneratorGenerate sinestream input signal for plant frequency response estimation (Since R2024a)
Start-Stop GeneratorGenerate start-stop signal used by signal generation, estimation, and autotuning blocks (Since R2024a)


Frequency Response Estimation Basics

Estimation Input Signals

Estimation Using Signal Generation Blocks

Noise and Time-Varying Inputs

Validation of Linearization

Code Generation