Chirp Input Signals
A swept-frequency cosine input signal, or chirp signal, excites your system at a range of
frequencies, such that the input frequency changes instantaneously.You can use a chirp input signal for frequency-response estimation at the command line
or in Linear Analysis Tool. The estimation algorithm injects the chirp signal at the input
point you specify for estimation, and measures the response at the output point. 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.Create Chirp Signals Using Linear Analysis Tool
In the Linear Analysis Tool, to use a chirp input signal for estimation, in the Estimation
tab, select Input Signal > Chirp. You can specify the frequency range and other
properties of the chirp in one of two ways:- Enter the values manually in the Create chirp input dialog box.
- Initialize the frequencies based on the dynamics of a linear model, such as a
linearization of your system.
To create a chirp signal based on a linear model:1 Obtain a linearized model, linsys1.For example, see “Linearize Simulink Model at Model Operating Point” on page 2-74,
which shows how to linearize a model.(^2) In the Linear Analysis Tool, in the Estimation tab, select Input Signal > Chirp.
5 Frequency Response Estimation