Use linearization I/O points to specify input and output points for frequency response estimation.
io(1) = linio('scdplane/Sum1',1) io(2) = linio('scdplane/Gain5',1,'output')
Identify all source blocks that generate time-varying signals in the signal path of the linearization outputs. Such time-varying signals can interfere with the signal at the linearization output points and produce inaccurate estimation results.
First, use frest.findSources to identify time-varying source blocks that can interfere with estimation. frest.findSources finds all time-varying source blocks in the signal path of the linearization output points.
Identify the time-varying source blocks in the scdplane model:
srcblks = frest.findSources('scdplane',io);
Next, to disable these blocks during estimation, use frestimateOptions.
opts = frestimateOptions; opts.BlocksToHoldConstant = srcblks;
Estimate the frequency response.
[sysest,simout] = frestimate('scdplane',io,input,opts);
sysest is the estimated frequency response. simout is the simulated output that is a Simulink.Timeseries object.
For more information about syntax and argument descriptions, see the frestimate reference page.
Tip To speed up your estimation or decrease memory requirements, see Managing Estimation Speed and Memory.
Open the Simulation Results Viewer to analyze the estimated frequency response. For example:
You can compare the estimated frequency response (sysest) to a system you linearized using exact linearization (sys):
For more information, see Analyzing Estimated Frequency Response.