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AD5933 Occasional Spurious Data

Question asked by jtm214 on Oct 15, 2014
Latest reply on Oct 22, 2014 by musach

Hi,

I'm using the AD5933 to monitor the impedances of various systems and the majority of the time it works fine, but every 50-100 samples I get a spurious reading that throws everything off.  I simplified the setup so that I continually take measurements at the same frequency using the repeat frequency command with a .01% precision resistor of 50 Ohms and the same thing happens.  I've inserted an image below of the real component of the DFT, the imaginary component does a similar thing but its usually not at the same sample as the real value.   The image below shows the real component jumping from ~10 to ~1000.  I've seen the value jump to a much larger value and it is enough to throw off the average of hundreds of samples.

 

Is there something in the setup that could be causing this or is there a way to deal with it?  I don't want to just throw out points because in practice I won't know exactly what the impedance is and it will change over time.

 

Any assistance will be appreciated.

Regards,

Justin

Real Data Plot.png

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