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Measure Transfer Functions Using Swept-Sine Excitation

 This video shows how to measure transfer functions in Simulink using a swept-sine excitation. This is one of the oldest techniques for measuring a transfer function because of its simplicity. This technique requires that we only excite our device-under-test at one frequency at a time and thus there is no need to perform any detailed spectral analysis in order to make a spectrum measurement. This technique is also very customizeable. The user has precise control over what frequencies to excite at, what excitation level to use at each frequency, and how long to dwell at each frequencies. Each of these values can be different per frequency. The big disadvantage of this measurement technique is its speed or lack thereof. Both magnitude and phase measurements are made in Simulink. The magnitude response measurement is based on computing a ratio of RMS values. The phase response measurement is based off of a difference in zero-crossing detection times. The title of the model uses the moniker "quick and dirty" because there are ways to improve the robustness of the measurement as shown and these are also discussed in the video. You can download this example on GitHub here:

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