Simulink Control Design™ - MathWorks

Specify whether the perturbation at each frequency is applied sequentially (Sinestream)
or simultaneously (Superposition).

• Sinestream — In this mode, a perturbation is applied at each frequency separately.
  You specify how many periods at each frequency to allow the system to settle using the
  Number of settling periods parameter. Specify how many periods to measure the
  response using the Number of estimation periods parameter. For more information
  about sinestream signals for estimation, see “Sinestream Input Signals” on page 5-37.


• Superposition — In this mode, the perturbation signal includes all specified
  frequencies at once. For frequency response estimation at a vector of frequencies ω =
  [ω 1 , ... , ωN] at amplitudes A = [A 1 , ... , AN], the perturbation signal is:

Δu=∑

i

Aisinωit.

Best practice is to use no more than about 50 frequencies in a superposition signal.

Sinestream mode can be more accurate and can accommodate a wider range of
frequencies than Superposition mode (see the Frequencies parameter). Sinestream
mode can also be less intrusive, because the total size of the perturbation is never bigger
than the values specified by the Amplitudes parameter. However, due to the sequential
nature of the sinestream perturbation, each frequency point you add increases the
recommended experiment time (see the start/stop input port for details). Thus, the
estimation experiment is typically much faster in Superposition mode with satisfactory
results.

Tip

Attempting to linearize a model containing a Frequency Response Estimator block using
superposition mode and more than 50 frequencies can generate an error. The error states
"The model contains too many elements for linearization. Please reduce the model size."
To complete linearization, you must either comment out the frequency-response estimator
block or reduce the number of frequencies.

Programmatic Use
Block Parameter: ExperimentMode
Type: character vector, string
Values: 'Sinestream' | 'Superposition'
Default: 'Sinestream'

Number of settling periods — Number of periods to wait for settling of
transients
2 (default) | positive integer | vector of positive integers

Frequency Response Estimator