Compare two DC voltage signals

Thread Starter

Anestis88

Joined Aug 9, 2011
19
Hi
I would like to ask what is the best approach if I have to compare two dc signals with a lot of fluctuations on them. I have already checked the frequency spectrum and I see no high frequency noise. However the signal fluctuates around +- 5% of the mean reference.
So, is it enough if I compare the mean values of these signals or any other digital filtering technique is better ?
 

Alec_t

Joined Sep 17, 2013
14,280
How much higher? Averaged over what time period? Or instantaneous? Updated how often? What will the comparison result be used for?
 

Thread Starter

Anestis88

Joined Aug 9, 2011
19
The signals are around 2.5V and I want to find a difference in mV accuracy. For example 3-4mV difference . My sampling is 2.5Gs/s with 12bit resolution. The period can be 10-20 usec. And inside this period I want to compare absolute values to find the difference of these signals.
 

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wayneh

Joined Sep 9, 2010
17,496
So if I understand, you want to capture a burst of two signals, each carrying a lot of noise, and produce an output that is proportional to the difference in the mean voltages of the two signals?

I think it would make sense to integrate each signal to produce a pair of "moving average" voltages, and then amplify the ∆V of the smoothed series.

It would also be valid to compute a mean and standard deviation for a captured data set. This approach would also give information about the noise and the significance of any ∆V between the means.
 
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