Time-Domain to Magnitude and Phase

Numerical inference of magnitude and phase information of streaming time domain input and output wav

Description

This s-function captures a sample of two (ideally oscillatory) signals and, using a FFT, computed the amplitude ratio and phase difference between the two signals during a simulation.

This is intended to provide a way to numerically generate nonlinear equivalents of Bode plots for either linear or nonlinear systems. By choosing a frequency of interest (e.g. an input frequency you select), you can compute the amplitude and phase of another signal, like the output of a nonlinear control system, with respect to the input. Bode plots are defined and available only for steady-state linear systems with transfer functions. This function allows you to numerically generate similar plots (after your system reaches dynamic steady state) for linerr or nonlinear systems.

• Required Products: Simulink
• MATLAB release: MATLAB 6.5 (R13)

[Srikar Vulli]

Hi,
 How did you guys solve the problem of 'Time-Scale' getting crushed in your case as well as MATLAB 'specgram' function ? (If you take a signal of length 'x', the final plots would be of 'x minus half the length of window'. I tried zero-padding the signal at the begining and the end. It seems, this idea is generating some erros at the begining and at the end when I tested a perfect 'Sine' wave using a window of length of 'one-cycle'. Any help please!!!

Srikar