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Backing Out Impulse Response From Signal

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Anthony LoCurto
Anthony LoCurto on 21 Aug 2019
Commented: Rajiv Singh on 26 Aug 2019
I am sure this has been answered somewhere, but I can't seem to locate an answer anywhere. I have a modeled signal and an experimentally obtained signal (taken with a 150 MHz photodiode). It is obvious that there is signal ringing associated with the impulse response. How could I (a) model the impulse response on the modeled signal, or (b) remove the impulse response from the experimentally obtained signal? With my current setup I can't measure the response of the photodiode with a Dirac-delta function input which is making this a little bit more difficult. I assume that I should be able to arrive at a transfer function for the photodiode. I tried convolving the model with a damped oscillator based on the photodiode specs, but that didn't give me the right solution.
ExperimentalPlot.png
ModelPlot.png
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Rajiv Singh
Rajiv Singh on 26 Aug 2019
No sure what you mean. But let us say you measured a certain signal "y" from a system. Pretend that the signal is in response to a impulsive impact applied to the system. Then your input can be u = [1; zeros(length(y)-1,1)]. Pack this data so:
z = iddata(y,u,Ts); % Ts is sampling interval of y.
model = ssest(z,2); % second order state-space
x = impulse(model); % x is the impulse response that you should compare to y
model can also be obtained using tfest, oe, impulseest etc.

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