Eliminate the periodic noise from the signals.

[mustice]

I have same problem too. There is an periodic noise on the acquired data. I use DAC0OUT. When I changed the power source signal becomes normal. What is the problem? look attached picture.

[billko]

I'm pretty sure you just answered your own question.

[mustice]

I know the problem origin. I must use dac0out not other power supply. I need to fix this problem. 

[billko]

Here's where you have to rely on your "engineering inquisitiveness" and figure this out for yourself, using the hints given above.  You've given absolutely no information except one picture with two graphs that have ambiguous labels.

Really, this isn't even a LabVIEW question.

[mustice]

If you the answer just write. If you dont know the answer just don't write. I think you are in second one.

[billko]

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@mustice wrote:

If you the answer just write. If you dont know the answer just don't write. I think you are in second one.

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It's true that I don't know the answer, but I am giving you valid advice on how to find it for yourself.  Read above.  No one has the answer for the OP, either.  It's just advice on how to arrive at the answer.

This is an environmental issue, not a programming one.  Two graphs showing some ambiguous signal that only you know anything about isn't going to get you much help.

Instead of wasting everyone's time complaining, give us something to work with.  We don't know what the signal represents, we don't know the equipment being used.  Nothing.  At.  All.  Except you seem to have something that occurs roughly three times in five seconds.

[Bob_Schor]

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@mustice wrote:

I have same problem too. There is an periodic noise on the acquired data. I use DAC0OUT. When I changed the power source signal becomes normal. What is the problem? look attached picture.

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@mustice:

Please do not "hijack" the Post/question of @Shrinivas.  Instead, make a post of your own.  We need to better understand your Data Acquisition problem better.  Please tell us:

• What you are trying to do (e.g. "I need to record such-and-such signals from this-and-that equipment at a rate of N kHz".
• What hardware you are using for the recording.
• What (if any) special sensors you are using.
• Whether you are recording Single-ended or Differential (if this is relevant), and how you are thinking about grounding and noise isolation.
• What LabVIEW software you are using (e.g. 32-bit LabVIEW 2018 SP1 with YYY package).
• If there is a "noise" problem, a picture of the noise (with a meaningful time base, please not a TimeStamp) might be helpful.
• If the problem might be "software", please attach the LabVIEW VIs (or, better, a compressed .zip file of the entire Project).

Again, start your own Post.

Bob Schor

[mustice]

Hello everyone,

I have some problem with my data acquisition setup. I use BNC 2090 for both driving voltage and collecting data. I observe some periodic noise (like spikes) from both output (DAC0) and input (ACH1). Collecting data noise from ACH1 is almost same frequency with DAC0. I also use a different power source however when I connect the measured signal cable to ACH1, periodic noise appears. In case using another power supply, without connecting measured signal to ACH1, it seems there is no periodic noise (using oscilloscope) . I would like measure nA range current blockages. These spikes completely effect my measurement. I recognize (using oscilloscope) that they changes with my data capture rate. My capture rate 250 kHz. Please find attached VI and some oscilloscope pics. For oscilloscope image above signal (yellow) is DAC0, below signal (purple) ACH1 (not consider at middle I use a RC filter for removing the noise)

[billko]

As I mentioned in the other topic you were posting in, this appears to be an environmental issue.  There were several excellent suggestions, but we can only guide you because we aren't there to actually be able to see all the noise generators lurking in and around your test area.  (By "noise generators", I am not referring to instruments whose purpose is to generate noise; I am referring to anything electrically noisy that may be emitting RF and/or line noise.)

I don't think this is a LabVIEW issue at all, but this is still a pretty good place to post because a lot of the LabVIEW experts here are test environment experts as well.

[johntrich1971]

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@mustice wrote:

Hello everyone,

I use BNC 2090 for both driving voltage and collecting data. 

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If I am not mistaken the BNC 2090 requires a DAQ card. What DAQ card are you using with the BNC 2090? Is your 250 kHz timing within the capabilities of the board?

Also, what are you trying to do in your AO loop? You're feeding Potential/V to a shift register that is negated every iteration, but you're never using that value. Why are you using a local variable for Potential/V when you could easily just use the wire?  Why are you stopping and starting the AO every iteration? Since you want a continuous signal why not use a continuous signal?