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.

  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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