needed inputs for measurements using NI9205

[Kyle_A.]

Hi Vishh,

For a quick description on low pass filters, you can check this article out.  Basically, you want to attenuate, or eliminate, frequencies that are higher than the desired signal you are looking for.  Since the frequency of your signal is low (almost DC, which by nature is 0 Hz frequency) you want to eliminate any noise at a higher frequency which could add to your signal.  Thus, you will want to 'pass' the low frequencies and reject higher frequencies.  This is done through a low pass filter.

Did that Butterworth filter help out your signal?  I cannot say which filter works best in your scenario, it usually takes some experimentation or calculations, but the main difference between different types of filters is the 3dB rolloff and some certain characteristics of the frequency response.

[kmmlvswnth]

Hi Kyle,

Thanks a lot for the mail. The butterworth filter seems working, I have attached a screen shot of the results. However I really appreciate if you could help me in refining them.

When I am using Voltage output range of +-10V, and using the increment  in voltage(by this I mean difference between two steps) > 0.1V,  my noise levels in the measured  readings are in the range of +-0.02V (20 mv). These readings are good. However when I use, very low increments like 0.0001v ( 1mv), noise levels in my readings haven't changed, so the increment is not captured in measured voltage values, and this distortion at low level increments is causing compounded error in my algorithm (this is a separate block, where I pass the measured force and displacement at every step and  calculate the displacement for next step).   

I tried changing the Voltage output(NI 9263) range to +-0.2V (200 mv) and then use low increments, still the results are same. Noise levels remain +-0.02V.  Any suggestions to deal such low level increments? can I further decrease my noise levels ?

Thanks in advance for your efforts and time.

[Kyle_A.]

Hi Vishh,

What happened to the noise level being at ±8 mV as you had indicated in previous posts?  Have you tried checking the noise levels with a 3rd party device?  Have you fully read this guide for field wiring and noise considerations?

[kmmlvswnth]

Hi Kyle,

Thanks for the reply. I got it, actually I was amplifying my noise because of a scale factor, I was creating virtual noise. Now I am good, Thanks for your efforts and time.