I have a csv file containing measurments a system's step response when the step is current and the output is the voltage. output looks something like this and the it's evenly sampledenter image description here

provided I know the current is a step function with amplitude A ,I'm asked to perform FFT on the data from the csv file and plot the Impdance Z on a logarithmic scale of the frequency f.

I have absolutly no idea where to begin so if someone fould provide direction i'll be grateful.

  • $\begingroup$ Z=V/I. ohms law $\endgroup$ – user28715 Jan 16 '19 at 16:02
  1. Your data capture doesn't seem good enough for an FFT analysis. It doesn't start at zero and it hasn't stopped wiggling at the end yet. You need a clean and complete step response
  2. If you had, you would take the derivative the step response to get the impulse response, do an FFT , invert it and properly scale (using calibrated data for voltage and current)
  3. This looks like a fairly straight forward RLC circuit. You can try to model this and try to identify the parameters by matching the modeled step response to the measure one. The R can be determined from the steady state part of the step response, the L from the damping time constant and the C from the resonance frequency.

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