A single ended earth grounded data-acquisition board has several inputs. Since it is single ended all input channels share the same ground when hooked up.
The thing is normally if there is no ground loop in the entire system and if I lets say plug in a new channel the other(already connected channels) channels' noise level and standard deviation is not affected.
But recently if I plug in a force transducer amplifier as an input to the same data-acquisition board the other channels' standard deviation increases for example from 0.005 to 0.032 ect. And when I observe what happens in FFT in real time is that when I plug in any of the force transducer amplifier as an input, other already connected input signals' white noise increases. There is no 50Hz related noise.
I can understand how 50Hz noise or harmonics appear in other inputs if there is ground loop. But in this case I couldn't find a ground loop and the noise type occurs in other channels seems like white noise.
How can this be explained?
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