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Oscilloscope integration error
2

Oscilloscope integration error

Oscilloscope integration error

(OP)
Hi,

Can anyone explain why my oscilloscope seems to have an error while performing an intergration function?  Even when the probe is shorted to itself, there is a ~1.0 mVs/s positive slope to the integration calculation (see attached picture).

I am measuring the total energy used by an electric motor and its supporting circuitry.  I connected a 0.1 ohm resistor in series with a battery terminal and hooked up a probe from an Agilent 54266D oscilloscope to either end of the resistor.  This way, the voltage output on the scope can directly translate to the current going through the resistor.

I am using the scope's integration function to calculate the total energy used during an actuation and I want to eliminate the effect that this 1.0 mVs/s error has on my results.

Thank you for your help.

RE: Oscilloscope integration error

2
All integrators, analogue or digital, have that problem. In your case, the AD:s offset seems to be the problem. Do an offset compensation, either directly on the input amplifier or in the integrator. Some integrators have a "leakage" function that keeps the integrator drift low. But that, of course, affects long term accuracy. Integrators are not easy to use.  

Gunnar Englund
www.gke.org
--------------------------------------
Half full - Half empty? I don't mind. It's what in it that counts.

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