The Bode plot obtained with a lock-in amplifier represents the system's response to small-signal (linearized) excitation. If application involves small input amplitudes around the same operating point, use this frequency response as a linear plant model.
For larger signals or different operating points, the actual system may deviate from this response. Use any one of the following toolboxes
- System Identification Toolbox
- Use idfrd to create a frequency response data object from measured data (frequency and complex response).
- Use tfest to estimate a transfer function model directly from the frequency response data.
2.Control System Toolbox
- Use invfreqs to fit a continuous-time transfer function to the frequency response data by specifying the number of poles and zeros.
- Use tf to create a transfer function object from the numerator and denominator coefficients obtained from invfreqs.
3.Simulink
- Use the Transfer Function block to implement and simulate the estimated transfer function model.
- Optionally, use the Frequency Response Data (FRD) block to simulate directly with the measured frequency response data.
For more details look into following documentation:
Hope this helps!
